» ENCYCLOPAEDIA BRITANNICA. EIGHTH EDITION. ENCYCL0PJ1DIA BRITANNICA OR DICTIONAKY OF ARTS, SCIENCES, AND GENERAL LITERATURE. EIGHTH EDITI0N. WITH EXTEN’SIVE IMPIIOVEMENTS AND ADDITIONS; AND NUMEROUS ENGRAVINGS. VOLUME III. ADAM AND CHARLES BLACK, EDINBURGH. MDCCCLIII. ^4c/r. ' . [ The Proprietors of this Work give notice that they reserve the right of Translating it.] ENCYCLOPEDIA BKITANNICA ANATOMY. BOOK II. DESCRIPTIVE, PARTICULAR, OR SPECIAL ANATOMY. i Special Special Anatomy may be defined to be that science, the Anatomy.^ provjnce 0f which is to determine the situation, shape, and component parts of the several textures and organs of which the human body consists. In the course of this, however, it is requisite to premise some observations on the external shape of the body, and the different regions into which it has, for the sake of greater precision, been divided. The external shape of the human body is so well known, that it is superfluous to describe it. Besides its division into right and left halves, anterior and posterior surfaces, it is divided into head, trunk, and extremities. The trunk is subdivided into neck {collum), chest {thorax, pectus), and belly {abdomen). The extremities are subdivided into tho¬ racic or upper, and pelvic, abdominal, or lower. The shape of the head is ellipsoidal, or oblong spheroidal; the greater diameter being antero-posterior, and the trans¬ verse smallest. The neck is cylindrical, spreading out above and below. The shape of the trunk is that of an irregular cylinder, flattened before and behind, broad above, and ta¬ pering below the chest, but expanding again at the pelvis. The extremities affect the cylindrical form, inclining to the conical. These several parts may be still further subdivided. The head is distinguished into two great divisions, the head pro¬ per, and the face. The former corresponds to the scalp, and may be divided into coronal, temporal, parietal, and occipi¬ tal regions. The coronal or syncipital may be reckoned from the anterior margin of the seal]) to the site of the an¬ terior fontanelle, or the line named the coronal suture. Be¬ hind this to the crown {vertex), and downwards on each side, are the parietal or lateral regions; from the parietal and frontal is the temporal; from the crown to the flexure of the neck is the hind-head or occipital {occiput) ; from the last point to the level of the shoulders is the cervix ; on each side are the lateral regions of the neck; and before is the laryngeal, jugular, or anterior region of the neck {jugidum). The face consists of the brow, front or forehead ( jrons), with the glabella or mesophryon at its base, in the middle, and the eyebrows {supercilia) on each side ; the nose {nasus), the upper lip {supralabium), the lower lip {infralabium), the chin {mentum), the cheeks {gence), the chops {buccce), the upper jaw {mala), and lower jaw {maxilla). Besides these, it is usual to distinguish the prolabium, or the red portion of the lip, upper and lower, as covered by a thin half-cutaneous, half-mucous skin and epidermis. VOL III. Distinc¬ tion into regions. The chest, besides its distinction into right and left halves, anterior arid posterior surfaces, and upper and lower boun¬ daries, may be distinguished into a sternal region in the middle {sternum), a mammary region on each side, an axillary region, a costal region, a hypochondriac region, a scapular region, and a vertebral region. Several of these regions it is convenient to subdivide in the following manner. The upper anterior region, imme¬ diately below the collar-bone, is distinguished as the sub- clavicular region; the space between the breast and the axilla as the extra-mammary region; that between the breast and the sternum as the intra-mammary region ; the space below the breasts on each side as the infra-mammary region ; the space below the armpit as the sub-axillary region. On the posterior surface of the chest, the space above the spine of the scapula is called the supra-spinal region ; that below it the infra-spinal region. The abdomen may be distinguished into regions in the following manner. The triangular space between the false ribs and navel, commonly named the pit of the stomach, is the epigastric region {scrobiculus cordis, epigastrium). Be¬ low this, in the centre, is the umbilical {umbilicus), with the iliac region or flanks, {ilia) on each side, and the hypogas¬ tric {hypogastrium) below. Behind, on each side of the vertebral column, are the loins, {lumbi). Next to the abdomen is the pelvis, the posterior lateral parts of which are the buttocks {nates), the anterior, the pubes, and the inferior, the hips or ischiatic regions {ischia), with the perinceum in the middle between them. In the trunk of the body, besides the chest, the abdomen, and the pelvis, it is proper to distinguish the region of the back-bone or spine, extending along the whole length of the trunk from the head to the lower end of the trunk. The spine or spinal region is divided into four subordinate regions; the cervical, the dorsal, the lumbar, and the sacral or sacro-coccygeal. In each pectoral extremity are recognized the following division; the shoulder {humerus), the armpit {axilla), the arm {brachium), the elbow {cubitus), the fore-arm {ante- brachium), the wrist {carpus), and the hand {manus). The latter is subdivided into the fore-wrist {metacarpus), the fingers {digiti), the palm {vola), and the back-hand {thenar). Each abdominal extremity presents the following separate regions; the haunch {coxa), the thigh {femur), the knee {genu), the ham {poples), the leg {tibia), of which there is the muscular part or calf {sura), the ankle external and in- A Special Anatomy. \ 2 ANATOMY. Special ternal {malleolus externus et internus), the foot (pes), sub- Anatomy. divided into the ankle-joint {tarsus), the foot-joint {meta- tarsus), the toes {digiti pedis), with dorsal or upper surface, and plantar surface or sole {soled). These divisions, though not so numerous as they have been made by some, are sufficiently so for the purpose of general anatomical description. Where more minute dis¬ tinction is requisite, it shall be introduced as we proceed. Descriptive or Special Anatomy includes not only the de¬ scriptions of the situations and relations of the different classes of textures in the human body and that of the inter¬ nal organs, but it comprehends also a particular form of anatomical knowledge necessary to the surgeon. This con¬ sists in defining, as accurately as language and measurement can do, the boundaries of the different regions into which the human body may be divided, and ascertaining the posi¬ tions and relations of all the important parts that are liable to become the seat of local disease and chirurgical operation. To this department the names of Chirurgical Anatomy, To¬ pographical Anatomy, and Anatomy of Regions, are given. The limits within which the present article must be con¬ fined permit not to enter upon this department of Anatomi¬ cal knowledge. It is sufficient to say, that useful treatises on this subject have been published by Velpeau, Blandin, Edwards ; and that in the systems of operative Surgery, especially that by Mr William Fergusson, and the work of Mr Maclise, correct information upon the boundaries and the relative positions of the various regions is communicated. Stature. The stature of the body varies in the two sexes, in indi¬ viduals, in families, in tribes, and in nations. The Romans, when they first visited Gaul, remarked the gigantic stature of the ancient inhabitants of that country compared with themselves; and, generally speaking, the modern Italians, though by no means a pure or unmixed breed from the an¬ cient stock, are a diminutive race. The Germans, and most of the English and Irish, are rather tall. The inhabitants of Finland are distinguished for their great stature, amidst the dwarfish tribes by which they are surrounded. In general the Europeans are taller than the Asiatics. Height or The average height of the adult male varies from 5 feet length. g inches to 5 feet 10 or 11 inches, or even to 6 feet. The dimensions of different parts vary according to those of the whole body; but the following measurements of a male of 5 feet 8 inches, and one of 5 feet 11 inches, may com¬ municate some idea of the length of different regions of the body. Inches. Inches. Total height 68'00 71'00 Between the tips of the middle fingers, with the arms extended 68-00 72'75 From the crown to the pubes 34’00 45’00 From the crown to the lower tip of the chin ... 9‘75 9'00 From the tip of the chin to the top of the breast 3’85 3'25 From the top of the breast to the pit of the sto¬ mach 6‘08 9-75 Between the pit of the stomach and the navel.. 6'08 7'00 Between the navel and top of the pubes 6-08 6*75 Between the top of the shoulder and the bend of the elbow 12'06 ^’OO From the bend of the elbow to the top of the hand 10,02 10’5 The hand, from the wrist to tip of middle finger 7'75 7*375 Between the top of the thigh inside and the knee inside 14*06 17*00 From the knee inside to the sole 18*05 20*00 The foot, from the heel to the point of the great toe 9*75 10*00 The average height of the female varies from 5 feet 3 inches to 5 feet 5 inches and 5 feet 7 or 8 inches. A woman Special of 5 feet 10 inches is unusually tall. The length of the dif- Anatom ferent regions is proportionally less than in the male. ■ The length of the body previous to adult age varies with the period of life. The length of an embryo of three weeks, represented by Soemmerring, is about g- of an inch ; one of eight weeks is about 1 inch ; and one at the end of the fifth month is about 10 inches. According to Burns, however, the length of the foetus in the fifth month does not exceed 6 or 7 inches ; in the sixth it is about 8 or 9, in the seventh about 12, and in the eighth about 15 inches. At the period of birth, the average length, according to Roederer, is about 20^ inches. The only part of the foetus of which it is important to de¬ termine the average dimensions at the period of birth is the head. Its largest diameter, which is that from the crown to the chin, is in general about 5 inches. The transverse diame¬ ter between the parietal protuberances is at the same time about Stt inches. Of 60 male and 60 female infants born at the full time, whose heads were measured by Dr Clarke, the circumference passing through the occipital process and the middle of the brow was at an average 13*8 inches, while the arch from ear to ear over the crown was 7*32 inches. One measured 15 inches in circumference, and one Sc¬ inches from ear to ear; but none were under 12 inches in the one direction, or 6^ inches in the other. It is well established that there is a difference in the aver¬ age dimensions of the male and female, even in the foetal state. Roederer found the mean length of 16 male children born at the full time to be 20|f inches, and of 8 females only 20t% ; and of the 60 male and 60 female infants measured by Dr Clarke, the average circumference was 14 inches in the former, and only 13f in the latter ; and the parietal arch was 7£ in the former, and 7£ in the latter. Of 120 infants, in 6 only, which were males, did the circumference of the head exceed 14^ inches. The weight of the adult male varies from 9 stone to 11 Weight, or 12. Ten stones, or 140 lb., may be stated as the average. The female weighs about 8 stone, and rarely more than 10. After the age of 35 or 40, when fat begins to be deposited, the weight rises considerably ; and the average weight at this age is from 13 to 14 stones. In some extraordinary ex¬ amples of corpulence, combined with large stature, the weight of the body amounts to 20 and 25 stones. The average weight of the foetus in the early months is uncertain. According to Mr Burns, it weighs about 2 oz. in the 12th week ; about 1 lb. in the 6th month; and about 4 or 5 lb. troy in the 8th month. At the period of birth the mean weight is about 7 lb. avoirdupois. Dr William Hun¬ ter states, that of several thousand new-born perfect infants weighed at the British Hospital in London by Dr Macaulay, the smallest was about 4 lb., the largest about 11 lb. 2 oz., and the greater number varied from 5 to 8 lb. avoirdupois. He knew no instance of a new-born infant weighing 12 lb. Of 60 male and 60 female infants weighed by Dr Clarke, the lightest was 41b., the heaviest 10 lb., and the average 71b. 13 dr. avoirdupois. The average weight of 26 children at the natural period, weighed by Roederer, was about 6^ lb.; the lightest about 5^ lb. and the heaviest about 8 lb. The difference between the weight of the male and fe¬ male infant at birth is estimated by Dr Clarke at about 9 oz. avoirdupois, which agrees with the results obtained by Roederer. In the case of twins, the average weight of each twin is in general less than that of children born at single births; but the combined weight of both is greater. Dr Clarke found the average weight of 12 twins to be 11 lb. avoirdupois each pair; the heaviest being 131b., and the lightest 8^-lb. Mr Burns, however, states that he has known instances in which Special Anatomy. Average weights of Individual Organs. ANATOMY. each twin was rather above than below the usual weight of a single-birth child. An important and useful point is to determine the average size and the dimensions of the principal organs of the human body in the adult state. Krause has, with this view, given the measurements of all the regions and the dimensions of most of the organs. All these modes of estimating the size of organs, however, are fallacious. The only one which can be employed with any precision is to ascertain the average weights of organs, and to note the proportion which these weights bear to that of the whole body. Attempts of this kind, applying, however, only to certain organs, have been made by different inquirers. The organs specified were found, according to numerous --trials made by Dr Clendinning, in males between the ages of 21 and 60 years, to weigh on an average, at the following rates— oz Gr. Lb. Oz. Brain 461 = 20,226 = 2 141 Heart 9Th — 3,982 Liver 531 = 23>408 = 35 Kidneys 9J = 4,025 Spleen 5 = 2,lb8 Pancreas 2§ = 1,148 Stomach 5 — 2>^88 Lungs 46 — 20,116 — 2 14 In the same persons the whole person weighed 941 pounds, which is between 46 and 48 pounds less than the average, 140 or 142 pounds (Quetelet), at the age of 40 years. Among the persons weighed, however, several were 124, 125, and 1261b.; two weighed 1401b., one weighed 1331b., and one at 50 years weighed 200 lb. These results differ in a very slight degree from those ob¬ tained by Dr Reid and Dr Peacock in the Royal Infirmary, Edinburgh. In 89 males the average weight of the heart amounted to 11 oz. 1 dr.; in 53 females to 9oz. 4 dr. In 60 males the average weight of the liver was 52 oz. 12^ dr.; in 25 females 45 oz. 3£ dr. The right kidney weighed, on an average in the male 5 oz. 7 dr.; in the female 14 oz. 13 dr. the left kidney 5 oz. 11 dr. in the male; in the fe¬ male 5 oz. 2 dr. / 7-r 7 7 7 \ • The average weight of the whole brain {Enkephalon) in 131 males, between the ages of 25 and 55 years, was found to be 50 oz. 3tVt dr-5 in females between the same periods to be 44 oz. 14ff dr.; giving a difference of 5 oz. 4*95 dr. in favour of the male brain. x_ The average weight of the brain proper {Cerebrum) m 95 males between the ages of 25 and 55 years, was found to be 44 oz. 3-4 dr.; in 58 females within the same periods to be 39oz. 3-3 dr.; making a difference of 5 oz. 0T dr. in favour of the cerebrum of the male. Special Anatomy has been divided, according to the classes of textures of which the human body is composed, into dif¬ ferent parts, with appropriate denominations. Thus the ana¬ tomy of the bones has been named Osteology, Osteography, and Skeletology ; while that of the soft parts in general has been denominated Surkology• Where more minuteness is attempted, the anatomy of the soft parts has been still fur¬ ther subdivided into that of the ligaments, Syndesmology ; the muscles, Myology ; the vessels, Angiology ; the nerves, Neurography and Neurology; the membmnes, Hymenology; the glands, Adenography and Adenology ; and the internal organs, Splanchnology. , Though these are convenient terms to designate the several divisions of Special Anatomy, they afford little as¬ sistance in the general arrangement of the subject. It is justly observed by Bichat, that this arrangement, if such it can be named, is objectionable, by separating different organs which ought to be united. It is indeed remarkable only for connecting organs by arbitrary, and often unna- Special tural principles; and though it may answer in a subor- Anatomy, dinate manner, it is unfit to furnish the principles of a general and natural mode of arrangement. The most eligible method is that which arranges the organs according to their physiological purposes,—a me¬ thod adopted by Haller and Soemmering, but which re¬ quired the hand of Bichat to give it its full and perfect developement, and which has since been adopted from this author by most subsequent writers. According to this method, the organs of the human body may be arranged in three great classes: first, those pertaining to the animal functions, or which establish the connection between the individual and the objects of the external world—the organs of relation; secondly, those pertaining to the organic functions, or which tend to the continuance of the individual—the organs of nutrition; and, thirdly, the organs relating to the continuance of the species—the organs of reproduction. The first class con¬ tains the organs of locomotion, speech, and sensation ; the second those of digestion, circulation and absorption, respi¬ ration, and secretion ; and to the third are referred the organs of generation. This method may not be altogether free from objec¬ tions ; several of which are anticipated by Bichat. It is sufficient, however, to observe that it is less objection¬ able than any other; and one of its advantages is, that it furnishes a clearer and more precise idea of the connec¬ tion of the different classes of organs of the animal body than any other yet proposed. This method of arrangement may be conveniently ex¬ hibited in the following table. I. Organs pertaining to the Animal, Voluntary, or Relative Functions. {Instruments—Bones, Cartilages, Ligaments, and Fibro-cartilages. Agents—Muscles, Tendons, and their appen¬ dages. f The Organs of Proper Sensation—Smell, Sight, J Hearing, and Taste. j The Organs of Common Sensation—Touch, k Tact, &c. ( Laryngeal Voice—the Larynx. -< Oral Voice or Speech—the Lips, Tongue, and ( Teeth. ( Central Organs—Brain, Cerebellum, and Spi- Energy, or In- < nal Chord, nervation. I Distributed Organs—the erves. 2. Sensation. 3. Voice. 4. Nervous II. Organs pertaining to the Organic or Nutritive Functions. f 1. Alimentary or Limitrophic Function. Digestion. ' Mastication—Mouth, Tongue, and Teeth. Deglutition—Pharynx and (Eso¬ phagus. Chymification—Stomach. Chylification—Duodenum and Ile¬ um. Defecation and Excretion—Colon v and Rectum. Lacteal Absorption—Lacteal s and Thoracic Duct. Nutritive Circulation—Heart and Blood-ves- sels. 2. Circulation. -{ Aerating Circulation, or Respiration—Lungs, ^ Secretory Circulation, or Secretion—Glands. III. Organs pertaining to the Reproductive Function. Male or Impregnating'! _ .. Organs. I procluct—the Foetus. Generation. Female or Ootrophic [ Organs. J 4 ANATOMY. Special Anatomv. PART I. ANATOMY OF THE ORGANS OF THE ANIMAL, VOLUNTARY, OR RELATIVE FUNCTIONS. The organs belonging to the functions of animal life are those of locomotion, sensation, voice, and innervation. 1 ese organs are distinguished by two general characters, symmetry of form and harmony of action. By the first !s meant that each organ possesses similar parts on each side of the mesial plane. By the second is meant that the action of that part which is on the right side of the mesial plane corresponds with that on the left. CHAP. I. THE ORGANS OF LOCOMOTION. The organs of locomotion may be arranged in two orders, active and passive. The first are the agents of motion, or the organic substances which produce motion; the se¬ cond are the bodies moved, or the instruments of motion. The muscles, strictly speaking, are the former, though to these are added certain appendages. The bones and their appendages constitute the second. With the latter order of parts it is usual to begin the business of special anatomy, for obvious reasons. The bones are at once the most durable and regular in shape of all the organic solids; and as an intimate relation sub¬ sists between their mechanical figure and the soft parts connected with them, the knowledge of the former con¬ stitutes the best introduction to that of the latter species of organs. SECT. I. OSTEOLOGY, SKELETOLOGY. The assemblage of bones composing the human body constitutes the skeleton, which, like the body, is divided into head, trunk, and extremities. The length of the skeleton is about an inch less than that of the body; that is, the skeleton of an individual 5 feet 8 inches in height is about 5 feet 7 inches long, and of one 6 feet, about 5 feet 11 inches long. The weight of the skeleton varies at dif¬ ferent periods of life. That of a middle-sized adult ranges between 160 and 200 ounces. A male skeleton, measur¬ ing 5 feet 6 inches long, I found to weigh 168 ounces, or 101 ]bs>j avoirdupois. The number of separate pieces amounts to 254, of which 56 belong to the trunk, 60 to the head, 72 to the pecto¬ ral extremities, and 66 to the pelvic. Of these several parts, the trunk is the most important, because, Is#, it is developed before the head or extremities; and, 2dly, be¬ cause if we look to its place in the animal kingdom ge¬ nerally, it is the most essential and constant, and pre¬ sents the general modulus or type according to which the osseous pieces composing the head are constructed. The Trunk. The trunk. The trunk of the skeleton consists of three parts, the spine or vertebral column, the chest or thorax, and the pelvis. §. 1. The Spinal or Vertebral Column. Vertebra!.) (Spina Dor si; wJer' '^ie ver*:e^)ra^ column, situate in the posterior part of Jumn. C°" I"jrunk’ length of which it determines, unites the head to the pelvis, supports the former, and is supported by the latter. When completely developed, it consists of 29, and rarely of 30 pieces, named vertebrae (spondyli, tf^ovSuXo/), from the circumstance that each admits of a slight degree of rotatory motion. .Twenty-four of these bones, which are in the healthy adult separate, are de- Special nominated true vertebrae (vertebra: verve). The 25th, Anatomy named the sacrum, though in adult life forming a single bone, consists in early life of four separate pieces, which ver^ become consolidated, and are therefore named false ver- brae tebrev, (vertebra: spuria:). The four last constitute what is named the coccyx, dhe column thus formed, though straight at birth, assumes afterwards several curvatures in the antero-posterior direction, giving it the aspect of the Italian f. It may be divided into four regions, the cervical, dorsal, lumbar, and sacral. In the first it is al¬ most straight, but begins to bend backward in the second, so as to form a considerable curvature with the convex surface posteriorly. A little below the middle of the dorsal portion it bends forward, and continues to do so to the lower part of the lumbar region, where it once more bends backward, and forms the sacrum into a concave hollow. At the lower end of the sacrum it again in¬ clines forward, and the coccyx is in general considerably incurvated anteriorly. (Plate XXVI. fig. 1.) Besides the antero-posterior curvatures, there is in ge¬ neral a lateral one near the lower part of the dorsal re¬ gion, on the left side, to which its concavity is directed. This has been observed by anatomists, from Cheselden, who first represented it, to Soemmering, Bichat, and Meckel. In length the vertebral column does not vary much ; and differences in stature depend more on the dimensions of the members than of it. In thickness it augments progressively from the cervical to the sacral portions, af¬ ter which it once more tapers to a point. It may be com¬ pared to two cones united by their base, the superior of which is truncated. The vertebrae, true and false, possess certain common characters. . Of these the most general is the annular shape, or a ring of bone, the opening of which, in conti¬ nuity with those of the whole column, constitutes a lon¬ gitudinal cylindrical cavity for lodging the spinal chord and its envelopes. It is therefore denominated the hole of the spinal marrow (foramen medulla: spinalis, Soem.), or simply the vertebral hole (Bichat). Anterior to this is a mass of bone, generally the largest of the vertebra, and therefore named its body (corpus vertebrae). The ante¬ rior surface is flat, sometimes slightly convex; the poste¬ rior is always concave; the upper and lower surfaces are slightly concave, and correspond with the intervertebral fibro-cartilages. Behind the hole the vertebra is moulded into an arch or annular segment, the outer surface of which forms seven processes. The first at the back of the vertebra on the median line is the spinous process, which may be said to be formed by the union of the spinal plates in the middle. On each side are two, which, from their situation with respect to the column, are named transverse pro¬ cesses. Other four, two on the upper and two on the lower surface of each vertebra, near the base of each transverse process, are named oblique, from their direction, and articular (processus articulares), because the inferior ones of the superior vertebra are articulated with the su¬ perior ones of the lower vertebra. These processes are easily distinguished by being covered with cartilage and synovial membrane. They constitute true capsular joints. Each vertebra presents four notches or depressions, two at the upper and two at the lower surface, between the body and the oblique processes. Each of these, with coiresponding notches on the vertebra above and below, forms a hole (foramen conjunctionis, vel intervertebrale), for the exit of the spinal nerves and the entrance of blood-vessels. ANATOMY. Special All the vertebrae, excepting the atlas and vertebra den- Anatomy. tata, are united in the same manner, and at the same points. The bodies are united by the intervertebral fibro- T he verte-carl;j]agegj which consist of white concentric annular lay- l,raB‘ ers of fibrous matter, placed in juxtaposition, and con¬ taining internally semifluid jelly. In adults this sub¬ stance becomes firm and consolidated ; but in the young subject it is so soft and compressible, that young persons are found to be one or two inches taller in the morning, or after they have been some time in the recumbent po¬ sition, than in the evening, or after the spinal column has sustained for some hours the weight of the person. In advanced life these fibro-cartilages become still more so¬ lid and shrivelled; and in some instances they are con¬ verted into bone, so as to unite two or more vertebrae in a single mass. This change is one reason of the greater stiffness and incurvation of the spine in the old and de- crepid, than in those in early life. Besides the connection by the intervertebral cartilages, the vertebrae are united at their articular processes by means of capsular ligaments, so as to allow slight flexion and extension on each other; and at the basis of the spinous processes, by means of short, firm, and inelastic yellow chords (ligamenta Jlava), named yellow ligaments. These, with a thick fibrous fascia extending along the anterior surface of the bodies (ligamentum anterius, fascia longitu- dinalis anterior)^ a similar fibrous fascia behind, lining the vertebral canal, a ligament connecting mutually the apices of the spinous processes, and the incumbent mus¬ cles, retain the vertebrae firmly in their places, and pre¬ vent them from being dislodged, unless by a force ade¬ quate to break the bones and rend the ligaments. The vertebrae vary in structure. The bodies consist chiefly of loose cancellated tissue, without solid bone. The spinal rings and the processes are much more firm and dense. In the foetus and infant each vertebra consists of three portions, a thick, loose mass, corresponding to the body, and two lateral arches corresponding to the spinal rings, without spinous process, and scarcely meeting. In the foetus, indeed, the posterior wall of the vertebral canal may be said to be incomplete. Soon after birth, however, the spinal plates enlarging, mutually coalesce on the me¬ dian line ; and from this point of union, by successive accre¬ tion, the spinous processes are gradually formed. These facts may serve in some degree to explain the facility with which tumblers and rope-dancers may be habituated in infancy to the most extraordinary inflexions of the trunk. The vertebrae, agreeing in the characters now enume¬ rated, differ from each other according to the regions which they occupy, and the parts with which they are connected. On this principle the twenty-four true ver¬ tebrae are arranged in three classes; the cervical {y. cer- vicis), the dorsal (y. dorsi), and the lumbar (v. lumborum). The cervical vertebrae are in number generally seven, rarely six or eight; the dorsal are twelve ; and the lum¬ bar are five. (Plate XXIV. and XXV. fig. 1.) The cervi- The cervical vertebrae are distinguished by their bodies brLVerte* keing small, with flat anterior surfaces; by the articular processes being short and flat, as well as less oblique than those of the others; by their transverse processes being short, of a triangular shape, hollowed above, and perfo¬ rated at the base by a hole for the transit of the vertebral artery; by the spinous processes being short, nearly hori¬ zontal, and generally bifid; and by the vertebral hole be- ing large and of an oval shape. ITn? atlas. The first and second of these vertebras are still further distinguished by peculiarities of configuration. The first, which is named atlas, consists of a large bony ring, inclos- 5 ing an irregular hole, approaching to the shape of the Special ancient tyre. Instead of the body, which is wanting, is Anatomy, a mere arch of dense bone, with an obtuse tubercle before for the longus colli muscle, and behind an articular facette Thf verte' which applies to a corresponding one of the tooth-like process of the second vertebra. From the extremities of this arch the vertebral hoop acquires considerable thick¬ ness, for the formation of the oblique and transverse pro¬ cesses. The superior oblique process is seen above on each side in the form of an elliptical cartilaginous surface, slightly concave, consisting of two parts, the anterior large, the posterior small, and terminating in a point which overhangs the sinuosity of the vertebral artery. The cavity of this superior oblique process receives the condyloid process of the occipital bone, with which it is connected by a capsular ligament, lined by synovial mem¬ brane. Below is seen the articular facette of the inferior oblique process, rounder, shorter, less concave, but cover¬ ed also by cartilage and synovial membrane, and articu¬ lated with the superior processes of the second vertebra. Between these two, on the lateral regions of the vertebral ring, is the transverse process, in the shape of a triangle, the base of which is formed by the bone of the oblique processes, and the sides by the production of the anterior and posterior arch. The latter, being the segment of a smaller circle, is more distinctly circular than the former, and may be described as a strong, dense, semiannular piece of bone, with a tubercle on its posterior margin at the median line, to which the rectus capitis posticus minor is attached. On the inside of the atlas, at the lower margin of the superior oblique process, is a rough surface with a depressed cavity, which marks the insertion of the trans¬ verse ligament. The space anterior to this is occupied by the tooth-like process of the second vertebra; that pos¬ terior to it, which is the proper vertebral hole, by the be¬ ginning of the spinal chord. The atlas is connected above to the occipital bone by the capsular ligament, which surrounds the margins of the superior oblique processes; below, to the vertebra dentata in the same manner; and behind its anterior arch to the tooth-like process. To its anterior tubercle are attached the longus colli and rectus capitis internus minor ; to the transverse process the rectus lateralis, the superior and inferior oblique muscles, the levator angidi scapulce, the transversi, the scalenus anticus, and the transversus colli. To its posterior arch the rectus posticus is attached. By the condyloid processes of the occipital bone moving on the superior oblique processes, the head is bent and extended, or moved backwards and forwards on the atlas. The atlas ossifies by two points. The second vertebra, named axis and epistropheus, from The axis, its motions, is distinguished by a large prominent body like a tooth (processus odontoides) issuing vertically from its body, a circumstance from which it is also named ver¬ tebra dentata. This process, which is a four-sided prism, with the top obliquely acuminated, presents on its ante¬ rior surface an articular facette, corresponding to that of the atlas. The posterior surface is rough, and corresponds to the transverse ligament. From the odontoid process the body descends somewhat below the level of the ver¬ tebral hoop, and presents at its lower margin, on the me¬ dian line, a tubercle, with excavations on each side. Above, on each side of the odontoid process, are the su¬ perior oblique processes, in the shape of oval facettes, covered by cartilage and synovial membrane, and articu¬ lated with the inferior oblique processes of the atlas. Below, and a little behind, is the inferior articular process, more oblique in direction, and articulating with that of the third vertebra. Between the two is the transverse pro- 6 ANATOMY. Special cess, with the vertebral hole in its base; and from the Anatomy. same point the spinal plates converge backwards so as to form the spinous process, which is distinct and bifid in braT^ thi8 vertebra. Between the superior oblique process is the upper notch, which is rather a rounding of the spinal plates than a distinct depression ; and between the inferior oblique process and the transverse process is the lower notch, which, with the upper one of the third vertebra, forms a complete hole for the exit of the fifth pair of spinal nerves. The vertebral hole in this vertebra is heart-shaped, the basis before and the apex behind. By the odontoid process it is articulated with the occipital bone and the atlas ; by the upper oblique process with the atlas; and by the lower oblique process with the third cervical vertebra. To the transverse process are attached the splenius ca¬ pitis, levator anguli scapulae, scalenus, transversus cervicis, longus colli, intertransversalis secundus anterior et posterior. To the spinous process are attached the rectus capitis pos¬ ticus major, obliquus inferior, spinalis cervicis, interspinalis cervicis, and multifidus spince. The axis ossifies from four points, one for each side, one for the body, and one for the odontoid process. The third, fourth, fifth, and sixth cervical vertebrae are very similar. The bodies gradually increase in size to the seventh, which is generally the largest. The articular processes are also more oblique in the lower ones than in those above. The spinous processes also increase in size in the lower cervical vertebrae, and in the sixth and seventh are particularly large and prominent; and in the last are not bifid, but merely tubercular. The vertebral holes in the second and third are heart-shaped, and the lower ones triangular, with the apex towards the spinous processes. The body of the seventh also presents at its lower margin a depression, which, with a corresponding one in the first dorsal, receives the head of the first rib. The seventh, in short, may be regarded as indicating the transition from the cervical to the dorsal vertebrae. Besides the muscles already mentioned as attached to the axis, to the cervical vertebrae are attached the lumbo- costalis, the serratus posticus superior, the rhomboideus minor, the cucullaris, the splenius capitis, the upper part of the large complexus, and part of the rhomboideus major. The dorsal The dorsal or thoracic vertebrae (y. dorsi vel thoracis), vertebrae, which are twelve in number, are distinguished by articu¬ lar notches on their superior and inferior margins, which, with the intervertebral cartilage and the contiguous ver¬ tebrae, form depressions for lodging the heads of the ribs, and cartilaginous facettes on their transverse processes for articulating with similar facettes on the tubercles of the ribs. The tenth dorsal vertebra has often only one fa- cette above, and the eleventh and twelfth have only a single facette for each of the two last ribs. The bodies of the dorsal vertebrae are more convex and somewhat rounder before than those of the cervical and lumbar. The hole, which is smaller, is also rounder, ap¬ proaching to the oval shape. The spinal plates are broad and strong, and meet be¬ hind in long prismatic spinous processes, which are direct¬ ed obliquely downwards, so that they are imbricated over each other, especially in the middle of the back. The three last are less oblique. The oblique direction and imbricated arrangement of the spinous processes are con¬ nected with the peculiar flexuous bend which the column undergoes from the lower part of the cervical to the upper end of the lumbar region. The twelfth dorsal vertebra approaches the first lum¬ bar in the large size of its body, in the shortness of its transverse processes, in the straight direction and smaller Specia extent of the spinous process, and in the articular processes Anatom; becoming almost vertical. To the dorsal vertebrae the following muscles are tached: the splenius capitis et colli, trachelo-mastoideus, the part of the complexus called biventer cervicis, the com¬ plexus, longus colli, transversus colli, spinalis colli, semispi- nalis dorsi, multifidus spince, the inner part of the lumbo- costalis, the levatores costarum, the inner layer of the ten¬ don of the internal oblique and transverse muscles of the belly, the latissimus dorsi, rhomboideus major, cucullaris, and serratus posticus superior et inferior. The five lumbar vertebrae are distinguished by the size The turn of their bodies and their processes, and by the directionbar vert£ of the spinous and articular processes. Each body is both h016, broader and thicker, but less convex, than those of the dorsal vertebrae. The vertebral hole also is larger, and it resumes the triangular shape as in the neck. The trans¬ verse processes are broad, flat, and large, without articu¬ lar facette like the dorsal, or arterial hole like the cervical, and are rough by the attachment of the sacro-lumbalis. Of the articular processes, which are large and have a vertical direction, the upper is concave, oval, and turned towards the median plane; the lower is convex, oval, and directed towards the lateral regions. The spinous pro¬ cesses are large, flattened, almost square, with thick obtuse margins, and directed straight backwards. The vertebral notches are large, and form holes much larger than at any other part of the spine. The attached muscles are the spinalis dorsi, multifidus spince, quadratus lumborum, the inner layer of the internal oblique and transverse, and the outer layer of the latter, the external and internal parts of the lumbo-costalis, the latissimus dorsi, serratus posticus inferior, the diaphragm, and the psoce. The sacrum, composed in early life of five pieces, which The sa- are afterwards consolidated into one, may be regarded ascrnin. a series of imperfect vertebrae conjoined into a single mass. It is a symmetrical bone, of a triangular shape, with the base attached to the last lumbar vertebra, the apex, which is obtuse, adhering to the os coccygis, and the sides wedged between the bones of the pelvis. The anterior or pelvic surface is concave, with the base, sometimes named the promontory,^rovoment and overhang¬ ing, the apex and the lateral margins incurvated forwards, and corresponds to the rectum. It presents in general four, sometimes five pairs of oval holes, which communicate with the spinal cavity, and between each of which may be seen a transverse ridge marking the lines of junction of the se¬ veral bones; and in some instances the inner is so imper¬ fect that a deep line is left. These holes, therefore, through which the nerves pass from the spinal chord, are quite analogous to those formed by the union of the ver¬ tebral notches. The posterior surface of the sacrum is much more irregular. At the top are two articular pro¬ cesses, concave and cartilaginous, for receiving the convex surface of the inferior articular processes of the last lum¬ bar vertebra. Outside of these is a deep notch, which, with that of the same vertebra, forms the posterior ver¬ tebral hole; and outside of this is a tubercle, which cor¬ responds to the transverse processes of the true vertebrae. Below the notch on each side is a series of four holes, which, like those of the anterior surface, communicate with the cavity of the bone, and allow the posterior nerves to issue from the chord. On the median line, between, there is an irregular bony ridge, or rather a series of three spinous processes, short, obtuse, and separated by shallow depressions. The third of these diminishes gra¬ dually in the longitudinal direction till it is entirely lost A N A 1 Special opposite the fourth pair of sacral holes, leaving between Anatomy. ridges a triangular opening, which often communi- cates with the interior of the spinal cavity, and, when it The verte-{joeg not} marks the lower termination of that cavity. In brse' the former case it is closed by the posterior sacro-coccy- geal ligament. The sides of the sacrum, which are rough, and of an ir¬ regular cuneiform shape, present two surfaces,—one ante¬ rior, something cartilaginous, for articulating with the iliac bones,—the other posterior, marked by two deep sinu¬ osities, in which are lodged the sacro-iliac ligaments. The inferior termination of the sides tapers towards the apex or coccygeal end. The surface is rough for the insertion of the sacro-ischiadic ligament, and it is terminated by a notch for the exit of the fifth pair of posterior sacral nerves. The structure of the sacrum, like that of the vertebrae, is cancellated, and most loose in the site of the spinal plates and processes. Its mode of ossification is analogous to that of the vertebrae generally. On the middle plane ap¬ pear five points, which correspond to the bodies of the false vertebrae, or the individual bodies of the sacrum ; and on each side of these are formed two others, which become eventually the ridges of bone between the ante¬ rior and posterior sacral holes and the spinal plates. As these enlarge, they coalesce; and consolidating, leave only on the pelvic and dorsal surfaces the rows of holes through which issue the sacral nerves. It hence results that the sacrum is ossified from fifteen separate portions of bone. Besides the muscles connected with the lumbar verte¬ brae, the sacrum gives attachment to part of the gluttzus maximus and the pyriformis. The sacrum is attached above to the last lumbar ver¬ tebra by the intervertebral fibro-cartilage, the capsule of the two articular processes, and the yellow ligament of the spinous processes; to the iliac bones by the sacro¬ iliac synchondrosis, and to the coccyx by a similar fibro- cartilage. (Plate XXIV. fig. 1, S.) The os The coccyx is a symmetrical bone, triangular, occupying coceygid. the posterior and inferior parts of the pelvis, attached by its base to the sacrum, and with the apex free and slightly incurvated forwards, so as to terminate in a hooked point, which has been supposed to resemble the bill of the cuckoo, (xoxjoiI;, cuculus.) The anterior or pelvic surface is concave, marked with transverse grooves covered by periosteum, and supporting the lower extremity of the rectum. The posterior or outer surface is convex, gibbous, and unequal, for the in¬ sertion of the sacro-coccygeal ligament and some fibres of the large glutceus, and, like the anterior, is also marked by transverse grooves. The base or upper end of the coccyx is concave be¬ fore for articulation with the sacrum, and presents behind two tubercles continuous with those of the spinal region, and on the sides two notches, which, with those of the sacrum, form holes for the fifth pair of sacral nerves. The margins of the bone are rough, for the attachment of the small sciatic ligament, and meet below at an angle, which is sometimes bifid, sometimes obtuse, and to which the levator ani is attached. The coccyx is generally cellular, with little density. The transverse grooves by which it is marked indicate its original separation into five portions, two of which be¬ coming united, leave four and occasionally three portions, an upper, a middle, and a lower. These portions, indeed, are so long in consolidating, that they are often separate in the adult. The first is the largest, and resembles a di¬ minutive vertebra without hole, and with truncated or un¬ developed processes. A lateral portion on each side pro- ' O M Y. 7 jects like a wing, the rudiments of the transverse pro- Special cesses; and the two tubercles above noticed, rising like Anatomy, horns, are imperfect articular processes, meeting those °f The s ine the os sacrum. The bony ridge which descends from e sPlne• these are imperfect spinal plates; and as these do not meet, they leave between them a groove corresponding to the anterior half of the vertebral hole; and the spinous processes are wanting. In the second coccygeal bone, which is rounder than the first, the aliform portions cor¬ responding to the transverse processes are also smaller than in the first; and in the third and fourth they are diminished so much that they are scarcely cognizable. The series of bones now described form by their union The spine what is called the backbone, chine, spine {spina dorsi), or generally, vertebral column. Viewed in connection, it may be dis¬ tinguished into an anterior and a posterior region, two late¬ ral surfaces, a base, and an apex. The anterior region is large in the neck, narrow in the back, and broad in the loins and pelvis. A series of trans¬ verse grooves of variable depth marks the bodies of the vertebrae ; and a series of transverse elevated ridges dis¬ tinguishes in like manner their upper and lower margins. These grooves, which in the cervical vertebrae are confined to the front, extend in the dorsal and lumbar to the sides. This anterior region is covered by the anterior vertebral ligament. On the sides it answers in the neck to the ante¬ rior or great recti, and the longi colli muscles ; in the chest to the latter, to the vena azygos on the right, and the thoracic aorta on the left; in the abdomen to the abdo¬ minal aorta and the inferior cava; and in the pelvis to the rectum. In the posterior region are seen, on the mesial plane, the row of spinous processes, horizontal above and below, and imbricated in the middle. The intervals, which are con¬ siderable in the neck and loins, are much contracted in the back, in which extension brings the processes in con¬ tact. The apices of all are in general in the same straight line; but this may be disturbed, either from the wrong direction of a process, or an unnatural position of a vertebra. On each side are seen the intervertebral grooves {fissures interspinales'), which commence at the occipital bone, and are continued with those of the sacrum. Broad and hori¬ zontal above, smaller and more oblique in the middle, very narrow below, these grooves are formed by the series of spinal plates, between which are left spaces varying in size according to the obliquity of the plates. These spaces are occupied within by the yellow ligaments, which being inserted at their inner surface, are something broader than the spaces, and without by the transversus spines muscle. On each side also is recognised a longitudinal hollow, extending from the atlas to the lower end of the sacrum. This hollow, which is formed by the spinous processes and the transverse processes with the spinal plates below, is superficial at the neck, narrow and deep in the back, and narrow and superficial at the loins and sacrum. In this longitudinal groove is lodged the muscle named multifidus spines. (Plate XXV. fig. 1.) The lateral regions present first the row of transverse processes, which vary in direction in different regions, chiefly in consequence of the spinal curvatures. Thus, if a vertical plane pass down along the sides of the column, the transverse processes of the neck and loins will be an¬ terior to it, while those of the back will be behind it. In the first region these processes are distinguished for form¬ ing, by the series of holes in the base of each, a bony canal traversed by the vertebral artery, and which is com- ANATOMY. 8 Special pleted in the intertransverse spaces by the intertransver- Anatcmy. colli. To these transverse processes numerous muscles are attached. Between them in the neck, and e sime. anterjor t0 them in the back and loins, is a series of holes formed by the union of the vertebral notches. Through these, which are the intervertebral holes (foramina inter- vertebralia), and which increase in size from the neck to the loins, where they are considerable, the anterior branches of the spinal nerves pass. Their shape is ellip¬ tical and their transit short. Anterior to these processes in the dorsal vertebrae are the depressed facettes, in which, with those of the fibro-cartilages, the heads of the ribs are lodged. The base of this column, which is supposed to be the last lumbar vertebra, is articulated with the sacrum in such a manner as to form an anterior convexity and a cavity behind. The base, however, may with greater justice be placed in the upper half of the sacrum, which, being firmly wedged between the thick posterior margins of the iliac bones, transmits to them, and thereby to the bones of the pelvic extremities, the weight of the trunk. The mechanism of this is similar to that of the keystone of an arch, which the sacrum truly represents. The perpen¬ dicular pressure on this bone is counteracted and balanced by the lateral pressure of the iliac bones ; and this lateral pressure is sustained, partly by their mutual pressure on each other before at the pubis, but chiefly by the oblique pressure of the neck of the thigh-bone, and the perpen¬ dicular pressure of the cylinder of the latter and those of the leg-bones. The upper extremity of the column, which is formed by the atlas and axis, receives the weight of the scull and its contents, which are exactly balanced on the articular cavities of the former bone. On this also the head is bent or extended by its proper muscles. Rotation is per¬ formed by the motion of the atlas with the head on the articular cavities of the second vertebra, and round its odontoid process. The holes of each vertebra form, by union, the verte¬ bral canal, in which are lodged the spinal chord, the origins of its nerves, and its membranous coverings. This canal, which is continuous with the cavity of the scull by means of the occipital hole above, and is completed by the sacral canal below, is not in the centre of the spine, nor is every¬ where of the same dimensions. Situate behind the vertebral bodies, and before the spinal plates, it is nearer the posterior than the anterior region of the column. Large at the neck and upper part of the back, it di¬ minishes below, and again enlarges in the loins. Its area is triangular in the cervical region, oval in the dorsal, and triangular again in the lumbar and sacral regions. It fol¬ lows the different curvatures of the spinal column. In the recent state, it is formed not by the bones only, but be¬ fore by the intervertebral cartilages, and behind by the yellow ligaments and the interspinales and intertransver- sales muscles. Lined by periosteum, by the posterior vertebral ligament, and by a quantity of loose cellular tis¬ sue, it is further covered by a cylindrical fibrous mem¬ brane, similar to the dura mater, the outer investment of the spinal chord; and within this are contained the liga- mentum denticulatum, the spinal arachnoid, and the spinal chord itself, with its anterior and posterior nervous roots on each side, and its appropriate blood-vessels. In early life the soft parts predominate; and the canal and its component bones are then susceptible of much freer and more extensive motion than afterwards, when ossification is complete, and the fibro-cartilages acquire firmness. In the human subject it may be viewed as a firm but flexible bony cylinder, which performs several functions at once. Resting on the sacrum, which is wedged im- Special movably between the iliac bones, it supports the trunk in Anatomy, the erect position, and transfers to the sacrum, on which it rests, the weight of the head, the chest, and great part e s^in& of the abdomen. In the vertebrated animals in general it incloses the spinal chord, one of the most essential and constant parts of the nervous system. In the several re¬ gions it forms a sort of posterior protecting wall to seve¬ ral important vital organs. Thus, in the neck it forms a posterior barrier to the oesophagus, the windpipe, and the great sympathetic. In the back it constitutes the poste¬ rior wall of the chest; and in the loins and pelvis it is the posterior wall of the abdominal viscera and the large vessels. In answering these ends, it is important to remark, that the firmness and mechanical arrangement of the spinous processes are of essential service. Their imbricated ar¬ rangement renders it impossible for any foreign body to enter the vertebral cavity and injure the spinal chord, unless between the occipital bone and atlas, or between the atlas and axis; and even at these points much preci¬ sion is requisite to enter the cavity. Between the axis and the third vertebra it is more difficult, and below this next to impossible, without breaking the spinous processes. With this character of security and support, the verte¬ bral column unites a high degree of flexibility. Though the degree of motion between each vertebra is trifling, yet between several it is considerable, and between the whole twenty-four it is multiplied to a great amount. The motions of which the vertebral articulations admit are those of flexion and extension, rotation, and lateral flexion. Of these, flexion is that which is most extensive ; for in the anterior direction there is less impediment to the motion of the vertebrae than behind, where the spinous processes allow no great extent of motion, unless where the habit has been acquired in early life, before ossification is completed. The rotatory motion of one vertebra on another is small; but by combining the motion of several or of the whole column, it becomes so extensive that some individuals can turn the head and neck more than half round. That these motions are the passive result chiefly of the inter¬ vertebral cartilages and the articulations of the oblique processes, may be inferred from the fact, that when the former are ossified, or the latter ankylosed, the motions are much impaired generally, and wholly destroyed in the vertebrae affected. The motions of the head on the atlas have been already shortly noticed. Those of the atlas and occipital bone on the axis are, though simple in effect, complex in me¬ chanism. The motion, indeed, is limited to that of rota¬ tion ; but this rotation is extensive. This is favoured by the horizontal position, and the large extent of the infe¬ rior articular processes of the atlas, and the superior ones of the axis, the looseness of the articular capsule, and the absence of spinous process in the atlas. The axis and its odontoid process becoming the fixed point, the atlas, and with it the occipital bone and scull, turn on the ellipti¬ cal flat articular surfaces, and on the odontoid process. On the first they glide extensively, and in opposite direc¬ tions, while the capsular ligaments are stretched. On the odontoid process the motion is more limited, and from right to left, and conversely; and in the latter variety of motion, the arch of the atlas before, and the transverse ligament behind, move on the anterior and posterior fa¬ cettes of the odontoid process. The anatomical construction of this articulation, how¬ ever, which is so favourable to extensive motion, is at¬ tended with the disadvantage of facilitating the luxation of the atlas on the axis. Luxation, indeed, may be re- ANATOMY. 9 Special garded as produced by too extensive motion of these Anatomy, bones, in which the articular processes of the former yer- tebra abandon those of the latter, and instead of resting The spine. on t}iemj are placed on the same plane, while the spinous processes are separated at least half an inch. It may be further observed, that the want of fibro-cartilages between these bones before, and of yellow ligaments behind, is favourable to displacement. The effect of this change of position on the spinal chord is obvious. While the one side of the atlas is thrust off the axis, the other is forced so near its body and articular process, that it compresses the spinal chord, and may occasion palsy or immediate death, by injuring the chord above the origins of the phrenic and intercostal nerves. The vertebral arteries at the same time undergo so much stretching, that the blood cannot move through them with the natural facility. ' It is nevertheless probable that displacement rarely oc¬ curs without such injury to the ligaments as to allow more extensive luxation than that now noticed. The odon¬ toid ligaments, or the transverse, may be ruptured; and in either case the odontoid process is allowed to slip backwards, and plunges into the chord, and destroys its texture almost instantly. These ligaments may be rup¬ tured either immediately by sudden violence, or in conse¬ quence of previous disease. In such circumstances, the injury done to the spinal chord is followed by almost im¬ mediate death, in consequence of the influence of the phrenic and intercostal nerves being suddenly suspended. In the same manner, the insertion of a cutting instrument between the occipital bone and atlas, or between the lat¬ ter and the axis, so as to divide partially or completely the spinal chord above the origin of these nerves, an ope¬ ration known by the name of ‘pithing, is followed by im¬ mediate death. § 2. The Chest. (Pectus, H-rftoz, Thorax.) The chest may be defined as an osteo-cartilaginous in¬ closure, of an irregular conoidal shape, flattened before, concave behind, and convex on the sides. Its upper ex¬ tremity is truncated. Its basis is irregularly oblique. It consists of the sternum before, the twelve dorsal vertebra behind, twelve ribs on each side, and twelve cartilages connecting the ribs and sternum. Tlie ster Tlie sternum {sternum, tfregm, os pectoris) is a symmetri- nuin or cal, oblong, flattened bone, broad above, narrow in the breast- middle, broad below, and terminating in a point placed bone. perpendicularly on the anterior of the chest. It presents two surfaces, an anterior and posterior, two extremities, an upper and lower, and two margins. (Plate XXIV. fig. 1.) The anterior or cutaneous surface, covered by skin, the aponeurosis of the sterno-mastoid and large pectoral muscles, and periosteum, is marked by fourtransverseridges at intervals of an inch, indicating the lines at which the separate portions of the bone were united. The posterior, internal, or mediastinal surface, is a little concave, occa¬ sionally marked by a longitudinal depression in its mid¬ dle; also presents transverse lines, but rather indistinct; is covered in the middle by the mediastinal cellular tis¬ sue, above by the sterno-hyoid and sterno-thyroid mus¬ cles, and on the sides by the triangulares sterni. The superior or clavicular extremity of the sternum presents three crescentic sinuosities; one on the middle, bounded on each side by an elevated peak, hollowed be¬ fore and behind, and one on each side, incrusted with cartilage and synovial membrane. The first of these cor¬ responds with the trachea on the inside, and has the sterno-mastoid muscle inserted on each outside. With the two lateral cartilaginous surfaces the sternal extremi¬ ties of the clavicles are articulated. Between the two is VOL. in. the interclavicular ligament, and all round are the liga- Special mentous fibres of the sterno-clavicular articulation. This Anatomy, upper extremity is about double the breadth of the b°ne at its middle. Below, the bone becomes narrow, and be- 16 slnIie‘ low the fourth ridge it seldom exceeds half an inch in breadth. Here it terminates in an appendage, which is generally named the pointed or ensiform cartilage (carti- lago mucronata, c. ensiformis). The shape of this is by no means always the same. In some subjects it is a flat, thin, and pointed process, not always very firm, but more solid than cartilage ; in others it is a flat thin bone, terminat¬ ing in two thin hooked points. In some it is obtuse and perforated. In some it is thrust forwards, in others it is bent inwards, or towards the one side. To this process the aponeuroses of the recti abdominis are attached. The margins of the sternum, which are generally about half an inch thick, present seven articular depressions crust¬ ed by cartilage. The first of these, in which the sternal extremity of the first rib is lodged, is, immediately below the clavicular depression, superficial and rounded. The others, which are situate at the ends of the transverse ridges, and receive the cartilages of the next six ribs, are deeper, angular, and surrounded by elevated margins, to which, in the recent state, the circumference of a capsular ligament is attached. In general, the seventh depression is formed partly on the sternum, partly on the ensiform cartilage; and the intervals between the depressions are smaller below than above. The sternum is chiefly cancellated, light, and loose, with little density, and a thin crust of compact bone. In the foetus and infant it consists of eight or nine square pieces, separated by transverse furrows, which, by the union of two, are easily reduced to seven, and afterwards to five. By the further union of two of these portions they are afterwards reduced to three; and in this state they re¬ main so long in some subjects that Soemmering describes the sternum not as one bone, but as three. I he first of these portions, which is uppermost, is irregularly heart- shaped, or rather octagonal, with the tracheal depression and the clavicular articulations above, the depression for the cartilage of the first rib on the side, and half of that for the second at its lower margin, where it unites with the second. The latter is merely the middle and longest portion of the bone, and is occasionally in three portions, sepa¬ rated at the costal depressions. The third or lower por¬ tion is the ensiform cartilage, the ossification of which renders the bone complete. The ribs may be defined to be long, flat, irregular'Ilie nl,s* bones, with an irregular semicircular curvature, placed on each side of the chest, at intervals of an inch or less, be¬ tween the dorsal vertebrm and the sternum. In general their number is twelve on each side, rarely eleven or thirteen. Of these, seven are connected with the sternum before by individual cartilages, and five are connected in¬ directly to the cartilage of the seventh, without attach¬ ment to the sternum. The former are denominated true or sterno-vertebral ribs (costae verce) ; the latter are styled false or vertebral (costae spurice, vel nothce). Each rib varies in length, breadth, and the direction of its curvature. The upper ribs are the shortest, and most incurvated in proportion to their length. The middle ribs, or the fourth, fifth, sixth, and seventh, are the longest, and form curves of the largest circle. The false ribs, which diminish in length from the eighth to the twelfth, are the least incurvated, or form curves of the largest circle. It is chiefly from the middle set that the common characters of these bones should be derived. Proceeding on this principle, we find that each rib may be defined as a broad, flat, longitudinal bone, not only in- B 10 ANATOMY Special curvated, but twisted from the direction of its original Anatomy, curvature. Each rib has a vertebral extremity, a cartila- '^P^^'ginous extremity, and a body. The vertebral extremity e nbs- consists of a tuberculated angular head (caput), with two cartilaginous facettes united at an angular line for inser¬ tion in the intervertebral depressions with which they are articulated. In the first and twelfth, and sometimes in the eleventh, there is one facette only corresponding to the single vertebra with which these bones are connected. Immediately before the head the rib is contracted and rounded, so as to form a neck (collum), which varies from five to six or seven lines in length; and before the neck is a tubercle or process (tuberculum) divided into two por¬ tions, one internal, smooth, cartilaginous, and uneven, ar¬ ticulated with the transverse processes of the dorsal ver¬ tebrae ; the other external, rough, giving attachment to the middle costo-transverse ligament. Anterior to the tubercle the rib is straight for about one inch, and rough by the insertion of the sacrolumbalis and longissimus dorsi muscles. Beyond this point, which is therefore named the angle (angulus), the rib begins to be incurvated cir¬ cularly, and bent downwards, so that the surfaces, which were external and internal, become obliquely superior and inferior. To prevent confusion, however, they must still be distinguished in the same manner. The outer surface of the rib, therefore, is convex, and forms the outer bend of the circle. Behind, it is covered by the latissimus dorsi muscle. The internal, which forms the inner bend of the circle, is convex above, and forms a concave hollow below, bounded by two sharp margins ; one proceeding straight from the head forwards, till it is lost about three inches from the cartilaginous ex¬ tremity ; the other, more acute, from the tubercle, and following the curvature of the rib to about two inches from the same point. In this groove are lodged the in¬ tercostal artery, vein, and nerve. The internal intercos- tals are attached to the inner lip of the margin ; the exter¬ nal to the outer. The upper margin of the rib is obtuse behind, where the external intercostals are inserted; but becomes acute and rough before, where the internal in¬ tercostals are inserted. The anterior or sternal extremi¬ ty of the rib is broad and large, and terminates in an oval hollow, in which the cartilage is inserted. In advanced life, when the union between the rib and cartilage is in¬ timate, this hollow becomes less distinct. Besides these common characters of the ribs, several pre¬ sent peculiarities deserving notice. The first rib is short, almost semicircular, and its direc¬ tion is such that its broad surfaces are superior and inferior, not external and internal, as in the others. The head of this rib possesses only one large articular facette, corre¬ sponding with the first dorsal vertebra, sometimes one large one, and a minute one corresponding with a small space of the last cervical vertebra. Its neck is short and round, and its tubercle is identified with the angle which is wanting. The superior surface of this rib is highly im¬ portant. From the head and tubercle extends a rough surface, in which are inserted part of the scalenus posticus, part of the serratus magnus, and the scalenus medius. Next to this is a smooth, deep depression, over which the sub¬ clavian artery passes; then is an eminence, to which the scalenus anticus is attached; afterwards a superficial hollow, in which the subclavian vein is lodged ; and, lastly, a rough surface at the sternal or anterior end, for the sub¬ clavian muscle. The lower surface of the first rib is un¬ even and slightly rough, but without groove at its outer margin. The second rib resembles the first in direction, hav¬ ing rather an upper and lower, than an external and in¬ ternal surface. The head is angular and acuminated, and Special the neck contracted; and the upper surface is rough by the Anatomy. serratus magnus ; but the lower surface, from the tubercle, begins to present an angle in the shape of an oblique sur- face, bounded below by a rough ridge, within which is the groove for the intercostal vessels and nerves. Ante¬ rior to this flat oblique surface the rib is twisted, and undergoes a change in direction. In the third the angle is not more distinct, and it is only in the fourth that this part is well marked. This character continues to the eleventh, when it becomes indistinct, and in which the tuberosity disappears, or at least is identified with the head, which has only one facette. The groove also is so short as scarcely to be observed. Lastly, the twelfth rib, which is often unconnected with the others by cartilage, is without tuberosity, groove, or angle, and has, like the first, only one facette at the head. The true ribs are connected to the sternum by means The costal of broad rounded pieces of cartilage, variable in length cartilages, and direction in different ribs. That of the first rib is very short, rather broad, and its direction, though oblique from above downwards, is more horizontal than that of the in¬ ferior ones. The angle at which it unites with the ster¬ num is acute above, and obtuse below. It is often ossi¬ fied in the adult. The second is nearly horizontal, and follows the direction of the rib to wdiich it is attached. Ihe next five are more oblique from above downwards, as the lower end of the sternum inclines forwards, and the corresponding ribs bulge towards the base of the chest. Each of these cartilages, invested by perichondrium, is attached by a rough surface to the anterior end of the rib; while the other extremity, which is rounded and covered by synovial membrane, is lodged in one of the articular depressions of the lateral margin of the sternum, and secured in this situation by a capsular ligament, strengthened by anterior and posterior fibrous bands. The anterior or outer surface of the thoracic cartilages is slightly convex, the internal or posterior surface flat, inclining to concave, lined by pleura and covered by the triangularis sterni muscle. The upper margin is concave, the lower convex, giving attachment to the internal inter¬ costal muscles, which in this region fill the intercartilagi- nous spaces. The cartilages of the five false ribs differ from those of the true, in not being articulated directly with the sternum. The cartilage of the eighth rib, after bending forwards and upwards, is attached to the seventh by a tapering point with a minute articular surface. The ninth cartilage is attached in a similar manner to the eighth, the tenth to the ninth, the eleventh to the tenth, and the twelfth is either attached in the same manner to the eleventh, or hangs free, though attached to muscles connected with the others. Hence the twelfth, and not unfrequently the eleventh, are denominated floating ribs. The whole of them are mutually connected by ligamentous fibres inserted into their perichondrial covering. The outer surface of these cartilages is covered by the recti and external ob¬ lique, the inner surface by the diaphragm and transversus. Connected with the ribs in the same manner in which those of the true ribs are, these cartilages differ, however, in taking a direction, first of descent, then of ascent or of curvature. The spaces which they leave between them, instead of being rhomboidal, as those of the true ribs, are irregularly triangular. In structure the costal cartilages belong to those of the cavities. Analogous to those of the larynx, they are dense, firm, elastic, whitish substances, without distinct traces of organization, and seem to consist chiefly of modi¬ fied gelatine, to which they are with difficulty reduced by ANATOMY. 11 Special long boiling. Their tendency to ossification is eonsider- Anatomy. able. In few persons above 45 or 50 are they quite free from bony points; and in many they are at this period converted into firm bone. The cartilage of the first rib, especially, is often firmly ossified before 35. When they undergo this change, certain points in their substance are observed to assume an orange or tawny colour, and to ex¬ hibit a porous arrangement, with great hardness, turning the edge of the knife. By long maceration the costal cartilages become soft and gelatinous, and are finally resolved into oval patches, separated by circular or spiral lines, with numerous per¬ forations. It was perhaps on this account that Herissant described them as consisting of spiral fibres. The chest The bones and cartilages now described, with the twelve in general, dorsal vertebrae behind, constitute the bony skeleton of the chest, bearing a remote resemblance to a cone, with truncated apex and oblique base, or, more accurately, to the frustum of a cone. To form a just idea of this assem¬ blage of parts, it is necessary to consider its surface ex¬ ternal and internal, its circumference above and below, its transverse diameter, and its longitudinal extent. The anterior region of the external surface, consisting of the sternum in the middle, and the cartilages on each side, is flattened, contracted above, wider and more promi¬ nent below. The intercostal spaces are filled between the sternum and the ribs by the internal intercostals, behind this by the external and internal, and covered by the anterior part of the large pectoral muscle. Behind, the chest presents the vertebrae with their processes, the transverse processes articulated with the tubercles, the angles forming a line obliquely receding from the spine, the transverse grooves, the longitudinal groove on each side filled by the multifidus spince, and the space be¬ tween the processes and the angles of the ribs occupied by the spinalis dor si, the longissimus dor si, and the sacro- lumbalis. The intercostal spaces, from the spine to the angles, are filled by the external intercostals ; and anterior to this are the two layers of muscles. The lateral regions of the chest are convex, making a larger sweep below than above. They present on each side eleven intercostal spaces, the superior of which are shorter and broader than the inferior. These spaces, which fol¬ low the curved direction of the ribs, cannot be accurately defined in shape. Between the angles and the cartilages, where the curvature is greatest, they are occupied by the double layer of the external and internal intercostal muscles, which, lying inclined in opposite directions, mu¬ tually decussate in this tract. The lateral region of the chest is covered above by the serratus magnus behind, and the two pectorals before; below by the external ob¬ lique on the side, and the recti before. The inferior lateral region, which is formed by the cartilages of the ribs, is therefore named the hypochondres (hypochondria). The inner surface of the chest is, before, correspond¬ ent to the outer surface, unless below, where the anterior inclination of the sternum makes the antero-posterior dia¬ meter greater. The posterior region is marked by the row of vertebral bodies, the prominence of which forms an imperfect partition, which separates the right and left halves of the thorax ; and which, notwithstanding the posterior bend which the spine undergoes between the second and eighth vertebrae, diminishes the antero-poste¬ rior diameter of the chest. On each side is a large con¬ cave hollow, narrow above, wide below, and swelling most capaciously in the middle, the walls of which, formed by the ribs and intercostal muscles, are lined by the pleura, and the cavity of which contains the lungs. The upper circumference of the chest, or its apex, is Snecial small, oval, transversely oblique from above downwards, Anatomy, and from behind forwards. Bounded before by the ster-1^^^^ num, behind by the first dorsal vertebra, and on the side by the first rib, it is diminished by the clavicles ; and vrhile its antero-posterior diameter is occupied by the wind¬ pipe, oesophagus, and the large vessels connected with the heart, its lateral portions are so much contracted, that each thoracic half (demithorax) has here almost a coni¬ cal termination. Its dimensions in the male skeleton of average size are about 16 inches. As the first rib has little or no motion, the upper circumference remains un¬ changed. The lower circumference of the chest, which is much more extensive, is said to be nearly four times larger than the upper. This, however, is exaggerated; and I find its greatest dimensions in the male to be 32 inches, exactly double the small circumference. It is suscep¬ tible of enlargement from the revolving motion of the ribs. The first rib remains fixed, while the lower ones are capable of being rolled outwards on their heads, tubercles and cartilages, so that the transverse diameter of the chest is enlarged. The lower circumference of the chest presents anteriorly a large triangular notch (ma- sura trigona), with the apex at the ensiform cartilage, the sides at the margins of the cartilage, and the base repre¬ sented by a transverse line uniting the tips of the twelfth rib on each side. This notch, which, in the recent state, is occupied by the heads of the recti muscles, with their fasciae in the middle, and the anterior margins of the ex¬ ternal oblique at the sides, constitutes what is called the pit of the stomach (scrobiculus cordis), or the epigastric region (epigastrium). The transverse diameter of the chest is small above, but gradually enlarges to the ninth or tenth rib. The average diameter measured between the inner margins of the first ribs on each side in the male skeleton is four and a half inches; the average diameter measured between the tips of the eleventh rib on each side is nine inches, which is also nearly the diameter between the inner mar¬ gins of the fifth ribs; and the average diameter measur¬ ed across the upper margin of the ninth rib, which is about the widest part, amounts to eleven inches. These diameters, it has been already said, are susceptible of slight enlargement, by reason of the lateral revolution of the ribs ; and this motion is most extensive between the sixth and tenth ribs. Above the sixth and below the tenth it is trifling. The longitudinal extent or altitude of the chest varies ; but in the same male skeleton it amounts to twelve inches measured between the lower margin of the first rib and the upper margin of the eleventh, which may be regarded as the inferior limit of the osseous part of the chest. From the top of the sternum to the plane of the ensiform cartilage the distance is five inches and a half. If from the lower margin of a mesial plane representing the medias¬ tinum, another plane be drawn on each side to the margins of the false ribs, the space inclosed on each side above this oblique plane will give some idea of the capacity of the thoracic cavities. The dimensions above stated apply chiefly to the adult male, from about thirty to thirty-five years, and of average size. In the female the chest is generally smaller in every direction, rounder, and more taper towards its inferior region. Above, as far as to the fourth rib, it is said to be larger and more uneven before, so that it has less of the conoidal shape than the male chest. It is also shorter. The pectoral cavity is in general symmetrical, that is, 12 ANATOMY. bones- Special of similar shape and dimensions on each side of the me- Anatomy. sial plane. Sometimes, however, without the interven- tion of disease, the greater convexity of two or three ribs on one side gives it a more ample appearance than on the other. § 3. The Pelvis. This is the name given to the irregular-shaped bony cincture which terminates the lower extremity of the trunk, and which is connected to the spinal column by means of the sacrum. It consists in the adult of four bones, two lateral portions (ossa coxarum), and two on the mesial plane, the sacrum and os coccygis. I he latter two have been already described. The lateral and anterior divisions now come under examination. These consist of two bones, one on each side, united with each other before by means of fibro-cartilage, and receiving between them behind, the sacrum, to which they are in like manner united by fibro-cartilage. Ihese bones, which are denominated ossa innominata, coxal or haunch-bones (ossa coxarum), are of a very irregular shape, and may be divided into three regions,^ the supe¬ rior or iliac, the anterior or pubal, and the inferior or ischial. These regions it is not easy to define accurately; but they will appear in the course of description, and they correspond to the original divisions of the bone in the foetal state. The coxal The coxal bone presents two surfaces, an external or femoral, and an internal or pelvic; and a circumference, divided into superior margin, anterior margin, inferior margin, and posterior margin. The external or femoral surface (dorsum), which is alter¬ nately concave and convex, presents behind a rough sur¬ face, to which the glutceus maximus is attached ; between this and a semi circular rough linealunated hollow, in which the origin of the glutceus medius is lodged ; and between the upper semicircular line and the lower a convex and con¬ cave area, for the attachment of the glutceus minimus, and one or two inequalities, to which one of the tendons of the rectusfemoris is attached. About an inch below is alarge hemi-spherical cavity, with elevated circular margins, inter¬ rupted at the anterior and inferior corner, named the aceta¬ bulum,or cotyloid cavity, forreceiving theheadof the thigh¬ bone. Its inner surface is covered by cartilage, unless at the centre, where is a depression for the attachment of the triangular ligament of the thigh-bone. The lower part of the margin is marked by a deep notch, over which, in the recent state, is stretched a ligament, thus forming a hole for the transit of the vessels and nerves of the articular cavity. The surface behind the acetabulum is slightly convex, indicating its union with the upper edge of a part of the coxal bone, distinguished by the name ot hip¬ bone (os ischii), and may be denominated the post-acetabu¬ lar or ilio-ischial eminence ; below, it is concave and sinuous, for the tendon of the obturator externus, and terminating in a sharp spine (spina ischii), to which the small sacro-sciatic ligament is attached. Anterior to the acetabulum is a large opening, named the thyroid or obturator hole, oval in the male, and triangular in the female, closed by a ligament at¬ tached to its circumference, unless at the upper part, where there is an obliquegroove forthe otorafor vessels and nerve. The outer surface of the thyroid ligament supports the obtu¬ rator externus muscle, the inner surface the obturator inter- nus. The upper margin of the thyroid hole is overhung by a convex ridge of bone, which is named the pubal or the hori¬ zontal branch of the pubal bone (ospubis, pecten, ospectinis) from supporting the parts of generation, and which termi¬ nates at its inner or mesial margin in a spine or tubercle, to which the outer portion of the tendon of the external oblique muscle is attached. The inner or anterior margin Special of the thyroid hole is bounded by a broad flat bone, irre-^nat«n|y^ gularly rough on the surface, broad above, where it is con*The coxa[ nected with the os pubis, narrow at the middle and lower bones_ part, where it joins the ischial bone. To the upper part of this, which is named the descending branch (ramus) ot the pubis are fixed the gracilis, the head of the adductores longus et brevis, part of the adductor magnus, and part of the obturator externus. The lower part, which is named the ascending branch (ramus) of the ischium, gives origin to the adductor magnus. The inner or pelvic surface (venter) of the coxal bone may be divided into three parts. The first is posterior, rough, and irregular, for articulation by fibro-cartilage with the lateral margin of the sacrum. The second, which is ab¬ dominal, concave, and is named the iliac pit (fossa iliaca), contains the belly of the iliacus interims, bounded above by the circumference or crest of the bone ; behind by a rough line which separates it from the sacral surface ; before by a concave irregular bend formed above by the iliac, below by the pubal bone ; and below by a sharp line (linea iho- pectinea), which is insensibly lost on the spine of the pubis, and to the inner end of which is attached a reflected por¬ tion of Poupart’s ligament, named the ligament of Gim- bernat. The third or pelvic surface, which is below, pre¬ sents behind a flat, irregular-shaped, concave space, occu¬ pied by the levator ani and part of the obturator internus, the inner opening of the thyroid hole, the inner surface of the rami of the pubal and ischial bones, with inequalities for the origin of the obturator internus, and a sinuosity below the ischial spine for the motion of its tendon. The circumference of the coxal bone is very irregular. The upper or iliac portion, which is semicircular, and is named the crest (crista ilium ossis), is rough for muscular and tendinous attachments, varying in breadth from half an inch to a whole one, and is distinguished into an exter¬ nal and internal lip, and an intermediate space. To the former are attached the external oblique, the latissimus dorsi, and the tensor vagince femoris; to the latter are attached the transversus and the quadratus lumborum ; and in the middle space between the two is the internal oblique. The posterior end of the crest terminates in the posterior superior spinous process, to which part ot the glutccus maximus and the ilio-lumbar ligament are at¬ tached, and below the posterior inferior spinous process forming the upper extremity of the ischiatic notch. 1 he crest terminates before in the anterior superior spinous process, to which are attached the fascia lata, the sartorius, and the upper end of the tendon ot the external oblique, or ligament of Poupart, or what is named the crural arch. The anterior portion presents, first a small sinuosity, which separates the superior from the inferior spinous process, to which is attached the upper tendon of the rectus cruris. Between this and an eminence in the upper or horizontal portion of the os pubis, marking its junction with the iliac bone, and which may be denominated the ilio-pubal, is a large sinuosity, in which are lodged the tapering ends of the iliacus internus and psoas magnus. Io the ilio-pubal eminence th e psoas parvus is attached; and within thepubal eminence, and anterior to the linea ilio-pectinea, is a trian¬ gular space, to which the origin of the pectineus is fixed. This part of the circumference is terminated by the spine of thepubal bone, to which the first insertion of Poupart’s ligament, or the outer pillar of the inguinal ring, is fixed. On the mesial side of this is a rough tubercular surface, which by means of fibro-cartilage is united with a similar surface on the opposite side. To this, which is named the symphysis pubis, the second insertion of the ligament of Poupart, the pyramidales and the recti, are fixed. ANATOMY. 13 Special Anatomy. The coxal bones. The posterior-inferior margin is most irregular. Com- By the cotyloid cavity it is articulated with the head of Special mencing with the posterior spinous processes, which are the thigh-bone. Anatomy. parted by a small notch, the margin is, immediately anterior tI^T^ to the lower process, formed into a large hollow, named The coxal bones on each side, with the sacrum wedged the ischiadic notch (incisura ischii), bounded before by between them behind, and the os coccygis attached to itsfn(j jts (jj_ the spine of the ischium, to which is attached the ante- extremity, constitute an irregular-shapqd osseous cine-mensions. rior sacro-ischiadic ligament, with the superior head of ture, something conical, with the base above, and the the gemellus without, and the coccygeus within. A pretty truncated apex below. This shape, with the manner in large hollow, in which play the belly and tendon of the which it supports the abdominal viscera and several of the obturator externus, separates the spine from the tuberosity urinary and genital organs, has given it the name of basin of the ischium, a large broad rough surface, the external (le bassin, das bccken, pelvis) or pelvis. In this it is requi- surface of which gives support to the quadratus and ad- site to consider the external and internal surface, the up- ductor magnus, the inner surface to the lower head of the per and lower circumference, the transverse diameters, ’ ’ ’ ' ^ 1" the direction, the outlets and their dimensions. The external surface comprehends four regions, the an¬ terior or pubal, the posterior or sacral, and two lateral. The anterior region presents the pubal articulation (symphysis) on the median line, and on each side the pubo-ischial rami, the thyroid hole and its margins, and gemellus and the external or inferior sacro-ischiadic ligi ment, while in the middle are fixed the long head of the biceps flexor, the semitendinosus, and the semimembranosus. From the tuberosity the margin of the bone along the ascending branch of the ischium, and the descending branch of the pubis, becomes narrow till it reaches the Structure. Deve lope- men t. symphysis, when it again becomes broad and more irregu- the acetabulum or articular cavity. The posterior region lar. To the former margin are attached the gracilis, presents on the median line the sacral spinous processes the transversus permcei, the erector, and the corpus ca- or spinous ridge, the triangular depression which termi- vernosum. The latter pniting with the opposite bone by nates the spinal canal, the suture uniting the sacrum to means of the interpubal fibro-cartilage, constitutes the the coccyx and the posterior convex surface of the latter; symphysis pubis. and on each side are the sacral grooves and posterior The iliac or coxal bones consist of cancellated matter, holes ; the processes by which they are bounded without; covered by a thin layer of compact bone. In early life, a deep depression corresponding to the sacro-iliac syn- and in delicate subjects, this cellular matter is loose, abun- chondrosis, and which is filled by a thick bundle of liga- dant, and rather thick. At a more advanced period, when mentous fibres ; and lastly, the posterior tuberosity of ossification is completed, and in strong muscular sub- the ilium, which projects much behind. The lateral re¬ jects, the proportion of this cancellated matter diminishes gions are formed by the dorsa or external fossa of the and sometimes disappears, so that the bone consists of two iliac bones, bounded below by the ischiadic notches, layers of dense, compact bone; and in some, even this, The internal surface of the pelvis consists of two por- in the iliac fossa, is destroyed entirely, so that the bone tions,—the one above, wide, capacious, and tapering perforated. downwards, forming the laige pelvis ; the other narrower. The coxal bone is formed originally of three pieces, one with walls nearly cylindrical, and forming a canal named for the large upper portion (os ilium), a second for the an- the small pelvis. terior or pubal (os pubis), and a third for the inferior or The large pelvis presents, behind, the sacro-vertebral ischial (os ischium). In the foetus, infant, and young sub- articulation and the sacral promontory, and on the sides ject, these three bones are seen quite distinctly separate, the internal iliac fossa. Before, where osseous parietes but adhering, by means of fibrous or fibro-cartilaginous are wanting, the space is occupied by the abdominal tissue, along a line drawn by the ilio-pubal eminence muscles. This constitutes the abdominal division of the through the acetabulum, and over its posterior convexity pelvis, and supports in the erect position part of the ileum into the ischial notch. At the same time the crest and and colon. Its transverse diameter, measured between margins of the ilium are covered by a cartilaginous epi- the crests of each iliac bone, amounts to nine inches in the physis ; the pubal bones are mutually attached by the male, and eleven in the female. same substance; the branches (rami) of the pubal and The large or abdominal division of the pelvis is bound- ischial bones are soft and membranous; the thyroid hole ed below by the ilio-pubal line on the sides and front, is merely a ligamentous notch; and the acetabulum is a and behind by a line drawn between the posterior extre- broad, irregular, superficial depression, with fibro-cartila- mities of each side, but following the surface of the sa- ginous margin. The connections of these three bones crum. The outline of this, which is elliptical, with the continue soft and cartilaginous for several years after birth, transverse diameter longest, and its plane inclined oblique- generally to the tenth, twelfth, or fourteenth, sometimes ly forwards, is named the superior outlet or aperture (am- later; and this is the reason why the os innominatum has bitus superior) of the pelvis, and it constitutes at once the been described as consisting of three bones, the os ilium, lower termination of the great and the upper boundary of os pubis, and ischium. After the last-mentioned period, the small pelvis. Its importance in the practice of mid- however, these bones are firmly consolidated into one wifery renders it necessary to distinguish its calibre, which piece, in which, nevertheless, the original marks of se- is larger in the female than in the male, into four dia- paration may be recognised in the ilio-pubal and post- meters. The first, antero-posterior, from the pubal sym- acetabular eminences above, and the meeting of the pubal physis to the sacral promontory, is from four to five and ischial rami below. The coxal bone, therefore, which inches in the male, and four inches nine lines in the fe- thus becomes a single solid piece in the adult, ought tc male. The second, transverse, measured between the be always described as such ; and the distinction into three iliac bones, is four inches six lines, sometimes five inches, in component parts, which is confined to the foetal and early the male, and five inches six lines in the female. Iwo period of life, belongs to the history of its ossification. others, drawn obliquely from the sacro-iliac synchondrosis The coxal bone is united to its fellow of the opposite to the ileo-pubal eminence, are about four and a half side by the symphysis pubis, and behind to the sacrum by inches in the male, and five inches in the female, the sacro-iliac fibro-cartilage (synchondrosis). Both of The small or proper pelvis, which is below this aperture, these junctions are occasionally ossified in advanced life, forms a sort of cylindrical osseous canal, more capacious, 14 ANATOMY. Special however, at its middle than at the extremities, the lower t\\epyriformis, the sciatic nerve and artery, the gluteal ar- Special outlet of which is diminished by the anterior incurvation of tery, and the internal pudic artery. The second is an ir- Anatomy. The nel ' ^ .sacr.um an^ coccyx, while the sides are bounded by regular triangular hole, smaller than the upper one, bound- generally,8 t^le isc^>0_Pubal branches. Before are the inner surfaces of ed above by the anterior ligament, below by the posterior The P^vis and its di- th? pubal symphysis and branches, corresponding to the one, and laterally by the sinuous hollow between the is-fndTts d’ mansions, urinary bladder ; behind, the pelvic surface of the sacrum, chial spine and tuberosity. Through this aperture the mensionV.' corresponding to the rectum ; laterally, the thyroid holes, tendon of the obturator internus passes out of the pelvis ; the inner surface of the ischial-bone and ilio-ischial June- and the external pudic artery and nerve, after bending tion, and the ischiatic notch, completed by the anterior round the upper ligament, re-enter the pelvis. The third and posterior sacro-ischiatic ligaments. space is a superficial notch, bounded on the outer or The upper circumference is very irregular, with its lateral side by the posterior ligament, and on the mesial plane slightly inclined forwards; larger in the female than side by the sacro-coccygeal bone. It is chiefly occupied in the male. It presents, behind, the sacro-vertebral ar- by celfular tissue. ticulation, bounded by a depression indicating the upper The dimensions of this inferior aperture are nearly the edge of the sacro-iliac synchondrosis; laterally, the two following. The antero-posterior diameter, from the coc- iliac crests terminating before in the anterior superior cygeal apex to the lower margin of the pubal symphy- spinous processes; before, the hollow of the iliacus inter- sis, is 3 inches in the male, and 4 inches 6 lines in the nus and psoas magnus, the ilio-pubal eminence, the hori- female. The transverse diameter between the ischial tu- zontal branch of the pubal bone, its spine, and lastly its berosities of each side is 3 inches 2 lines in the male, and symphysis. 4 inches in the female. The oblique diameter, measured The lower circumference, which corresponds with the from the middle of one of the great sacro-sciatic ligaments inferior aperture or ano-perineal outlet of the pelvis (am- to the opposite ischial tuberosity, is about 4 inches in the bitus inferior)^ is directed downwards and backwards, male, and from 41 to 5 in the female. Of these diame- Bounded behind by the coccygeal bone, and on the sides ters the antero-posterior is most liable to vary, by reason by the ischial tuberosities, this outlet is thus distinguished of the mobility of the os coccygis; but independent of this, for three eminences, separated by an equal number of it is always larger in the female than in the male, in con- notches. The situation of these eminences indicates the sequence of the sacrum being less incurvated, and.de- limits of the lower pelvic aperture. I he size and dispo- scending more in a straight line. It further appears, that sition of the notches is inversely to that of the eminences ; in females who have born children the incurvation of the and their arrangement is such that an eminence is oppo- sacrum is much less than in those who have not. site to a notch, and conversely. Thus the anterior notch, The direction of the pelvis is not horizontal, nor does it which is formed by the pubal arch, is opposite to the correspond with that of the trunk. Articulated behind with sacro-coccygeal eminence behind; and though the ischial the lumbar portion of the spinal column, the axis of which tuberosities appear opposite to each other in one sense, is inclined considerably forward from the vertical plane, strictly speaking their plane is each accurately opposed to the pelvis partakes of the same inclination. A horizontal the opposite sacro-ischial notch. The anterior notch is line drawn from the pubis towards the sacrum passes in terminated above by an acute angle in the male, in con- general an inch below the tip of the coccyx; and with sequence of the proximity of the pubo-ischial branches this a line drawn from the pelvis to the upper margin of which form its sides, but by a rounded arch in the female, the sacrum, representing the plane of the pelvis, makes by reason of the separation of these branches on each an angle of between 80° and 85°. The sacrum inclines side. In this notch are situate the generative organs of from the vertical plane about 35°; but the inclination of both sexes. The lateral notches, which are bounded be- the superior and inferior pelvic apertures varies. An hind by the sacrum and coccyx, before by the spine and imaginary line drawn from the tip of the coccyx to the tuberosity of the ischium, are irregular in shape, and are centre of the small pelvis, to represent the axis, cuts the each subdivided into three portions by the sacro-sciatic line of inclination at an angle of 75°. The most accurate ligaments, which secure the articulation of the sacrum axis of the pelvis is a line drawn at right angles to the and coxal bones. The first of these ligaments, the poste- plane of the pelvis as above found. rior or external, arising from the posterior extremity of The dimensions given above are sufficient to show that the iliac crest, from the sides and transverse processes of the female pelvis is much more capacious and ample la¬ the sacrum and coccyx by a broad, firm web of fibres, terally than the male. In the female, indeed, it is im- becoming small and thick at the middle, again expands, portant to remark that the upper region of the coxal and is inserted into the ischial tuberosity. This ligament bones is more prominent laterally, and hence renders the corresponds behind to the glutceus maximus, which is part- haunches prominent and rounded, and the outline of the ly attached to it, before and mesially to the small or an- abdominal aperture more extensive; the sacro-vertebral terior ligament to which it is united. The small or ante- angle is less prominent, and the sacrum is broader and rior sacro- sciatic ligament rises, in common with the large less incurvated; the arch of the pubis is wider and less an- one, from the transverse processes of the sacrum and coc- gular; the ischial tuberosities are more apart, and the cyx, and adhering to it for half an inch, passes more ho- cotyloid cavities even are at more distance from each rizontally outwards to the ischial spine, in which it is im- other,—a circumstance which determines the peculiar gait planted by a broad, thick, fibrous web. Behind, it corre- of the female. The male pelvis, on the contrary, is sponds at its sacral end, and for an inch from this to the deeper than the female. posterior ligament, and laterally to the pudic vessels and In the infant the pelvis is small compared with the size nerve; before, it serves with the posterior to complete of other bones, and of the parts which it is to contain, the lower circumference of the pelvis. The dimensions of this part, in early life, are indeed so By these two ligaments the ischiadic notch is in this limited, that not even the urinary bladder can be said to manner converted into two apertures and a notch. The be contained within it. As puberty approaches, the dis- first of these is superior, and is bounded above by the ilio- tinctive characters of the male and female pelvis begin to ischial arch, and below by the small ligament and part of appear. While in both sexes the bones become larger the posterior or large ligament. Through this hole pass and the cavity more capacious, in the female the addi- ANATOMY. Special tional amplitude appears in the width of the haunches, Anatomy. anj their remarkable projection beyond the flanks. The head. The Head. The upper or atlantal extremity of the vertebral column supports the head, a complicated assemblage of bones, the general shape of which is spheroidal above and behind, and irregularly cubical before and below. It is naturally divided into two parts, which are distinguished by their mechanism, their use, and the mode of their develope- ment. The first of these, the scull or cranium (xgav/ov, calvaria), fbrms a spheroidal bony case, occupying the superior and posterior region chiefly of the head. The second, which is the face, is formed above by an irregular pile of bones, articulated immovably to the anterior infe¬ rior part of the scull, and below by a single symmetrical bone, articulated movably to the middle of the lower part of the scull. § 4. The Scull. (Cranium, Calvaria.') The scull. The scull consists of eight bones, four of which are symmetrical and arranged on the mesial plane, and four arranged in pairs on gach side. The four symmetrical bones are the frontal, the ethmoid, the sphenoid, and the occipital; the four lateral are the two parietal and two temporal bones. 1 n me1" ^ie ^ronta^ bone (ps fronds, os coronce, synciput) is a ui >one. Symmetrical bone occupying the anterior part of the scull, and forming the anterior part of the scalp and the part of the face distinguished as the brow (from). It may be divided into three surfaces, the external or fron¬ tal, the inferior or orbito-ethmoidal, and the internal or the cerebral, and a circumference. The external surface is frontal and temporal. The frontal surface, which is convex and regularly arched, presents on the median line a ridge, indicating the original separation of the bone in two halves, the na¬ sal protuberance, more convex in age than in youth, and corresponding to the smooth interval between the eye¬ brows (glabella), a serrated margin articulated in the middle with the nasal bones, on the sides with the ascend¬ ing processes of the superior maxillary bones, and, lastly, the nasal spine, which supports the nasal bones. (Plate XXV. fig. 2. n.) On each side of the median line are the large smooth surface of the upper part of the frontal bone, the frontal protuberances (tubera fronds), large in youth, small in advanced age; the superciliary arch (supercilium), an irregular convexity extending transversely about an inch on each side of the mesial line, most prominent v/ithin, where the corrugator supercilii is fixed; and, lastly, the orbitar arch, large and prominent at its temporal angle, smaller and more rounded at its nasal, and presenting either a hole, or a notch covered by a ligament (c. c.), and through which pass the frontal artery and nerve. The nasal end of the orbitar arch, sometimes named the internal angular process, is insensibly lost in the serrat¬ ed surface, where it joins the superior maxillary bone. The temporal process, which is prominent, terminates in a serrated surface, which is articulated with the ma¬ lar bone. Exterior to the frontal protuberance is a curvi¬ linear ridge (d.), which gives attachment to the fascia of the temporal muscle, denotes the anterior boundary of the space in which that muscle is lodged, and separates the proper frontal from the temporal surface of the frontal bone. This ridge, descending in a circular direction, terminates in the temporal process at the opposite side to that of the orbital arch (a. a.) The triangular segment cut off by it is convex above and concave below. The orbito-ethmoid surface is irregular. It presents Special first on the median line a quadrilateral notch with serrated Anatomy, margins, in which the ethmoid bone is articulated. These margins consist in adult subjects of two plates, between fron* which are seen segments of the frontal and ethmoidal sinuses. In the outer of these tables are generally one or two holes, or notches, which, with the ethmoid bone, form holes (foramen orbitarium internum anterius et posterius). Through the former pass the ethmoidal twig of the nasal branch of the ophthalmic nerve ; through the latter the posterior ethmoidal artery and vein. On each side of the ethmoidal groove is a triangular concave surface, which forms the vault of the orbit, near the outer margin of which, and within the external angular process, is a super¬ ficial pit for the lacrymal gland, and towards the nasal side a depression for the reflected tendon of the superior oblique muscle. The internal or cerebral surface, which is concave, covered by the dura mater, presents on the median line a groove, the beginning of the sagittal, in which the supe¬ rior longitudinal sinus is lodged, and the margins of which, converging below, form a crest corresponding to the up¬ per margin of the falx. Below this is the foramen ccecum, which in the bone communicates with the two canals be¬ longing to the nasal bones, but in the recent state allows some veins to pass from the nose to the longitudinal sinus. It is sometimes common to the frontal and eth¬ moid bones. (Plate XXV. fig. 3. c.) On each side the frontal bone presents the large cavities, in which are contained the anterior extremities of the hemispheres of the brain; and above these the bones rise in the manner of a vaulted arch. The whole inner sur¬ face is moulded into alternate pits and eminences, called digital and mammillary respectively, and which corre¬ spond to the eminences and depressions of the cerebral convolutions. These are most conspicuous at the lower part, where the surface is traversed by minute vascular grooves. The circumference of the bone is serrated all round, for articulation with the contiguous bones. The posterior margin is nearly of an elliptical outline, straight, and in¬ terrupted below by the quadrilateral notch. Above, where the frontal is articulated with the parietal bones, the ser¬ rated processes proceeding from the outer table are largest and longest. Below, where the frontal is articu¬ lated with the lower angle of the parietal and wing of the sphenoid bone, the internal table is most prominent, so that the spheno-parietal suture is imbricated. Between the temporal and orbitar fossae this separation of the tables forms a triangular rough surface, which is articulated with a similar one, the triarcual surface of the sphenoid bone; and between this and the quadrilateral notch the margin is articulated in the same manner with the anterior mar¬ gin of the sphenoid bone. Lastly, the serrated and cel¬ lular margins of the quadrilateral notch are connected with the ethmoid bone. Besides these cranial bones, the frontal is articulated with the following bones of the face,—the nasal bones by the middle of the nasal suture, the superior maxillary bones by its sides, the lacrymal bones by the anterior end of the ethmoidal groove, and with the malar bones by the external angular processes. The frontal bone, which is thick at the nasal protube¬ rance and the external processes, and thin at the orbitay regions, is ossified by two points, which, appearing at the frontal protuberances, proceed by radiation as from a cen¬ tre towards the circumference of the bone. In the foetus and early infancy the bone thus consists of two lateral portions placed between the pericranium and dura mater% J<> ANATOM Y. Special with a longitudinal interval on the mesial plane, a trans- ^Anatomy^ verse one on the sit;e of the corona] suture) an(j a trian. The fron- gVlar cha.s™ at the ang]e between the two. This chasm, tal hone. witb a similar one between the frontal bones, forms a quadrilateral lozenge-shaped space, at which the motion of the brain is distinctly felt both at birth and for months after, and which is therefore named the fontanelle, or the 'dwter'xov fontanelle (fans pulsatilis ; bregma), or the open of the head. As the ossific process aclvances, the lateral margins of the bone extend, and the mesial margins ex¬ tending mutually, at length coalesce, first at the nasal protuberance and along the forehead, afterwards above, un¬ til the fontanelle is progressively diminished and at length obliterated. This junction is effected by the formation of serrated processes, which are mutually dove-tailed into each other; and for some years after birth the frontal bone consists of two similar halves articulated by a middle suture. In some few instances, especially in the female, this continues for many years; and the individual is found after death to have the frontal bone in two halves, with a middle suture. More frequently, however, the suture is obliterated by the consolidation of its serrated margins, and the frontal bone consists of one piece. The points of ossification remain long distinct in the form of the frontal protuberances. But eventually, from the uni¬ form elevation of the margins of the bone, they become less conspicuous ; and in old age they disappear more or less completely, leaving a surface uniformly uneven. The eth- The ethmoid or sieve-like bone (ps cribriforme), which mold bone. js symmetrical, and occupies the quadrilateral notch of the frontal bone, consists of several bony plates ar¬ ranged at right angles, and parallel with each other, so as to give the whole a cubical shape. It consists of four parts, a horizontal plate, occupying both sides of the mesial plane; a vertical plate at right angles to it, and corresponding with the mesial plane; and a lateral plate on each side, also vertical and parallel to the middle plate. In the bone thus formed the following circumstances de¬ serve attention. (Fig. 5.) The superior surface, cerebral, covered by dura mater, is formed by the horizontal plate, perforated by numerous holes {lamina cribrosa), through which pass the fibrils of the olfacient or first pair of nerves depressed longitu¬ dinally on each side, but surmounted in the middle to¬ wards its anterior half by a strong process of a triangular shape, named the cock’s comb (crista galli), and to which is attached the anterior inferior extremity of the falx, or dichotomous membrane. The anterior margin of this process is generally marked by a groove which, with that of the frontal bone, forms a passage for the nasal vein into the longitudinal sinus. The posterior margin of the per¬ forated plate is marked by an angular notch between two horns, for articulation with a salient angle of the sphenoid bone. The crista galli may be regarded as the upper di¬ vision of the vertical plate, which occupies the mesial plane, and which is thick and sometimes bifid before, but thin and rough behind, where it acts as a partition to the lateral halves of the ethmoidal cavities. The sides of this middle vertical plate are furrowed by minute canals (ca- nalicult), traced from the foramina, above, in which the nervous fibres are lodged. This plate, and indeed the lower surface of the perforated plate, are covered by a fibro-mucous membrane, which has been named the pitui¬ tary or the Schneiderian. The vertical ethmoid plate is articulated at its lower margin with the vomer and the tri¬ angular cartilage of the nose, before with the nasal spine of the frontal bone, and behind with the median crest (processus azygos) of the sphenoid bone. The lateral portions of the ethmoid bone consist exter¬ nally of a smooth flat bone (os planum of the ancients), Special which forms the inner or nasal wall of the orbit, internal- Anatomy, ly of two bones convoluted on themselves, and which are distinguished as the superior and middle turbinated bones Th® e(th- (conclue, ossa turbinata superiora et media, ossa spongi-ni0Ul bime' osa). These bones are seen most distinctly behind; but to form a correct notion of their figure, it is requisite to detach the lateral portions and examine them separately, when the following peculiarities may be recognised. The ossa plana on each side terminate in concave oblong quadrilateral plates, diverging outwards from the vertical plane. At the internal edge of these quadrilateral plates is seen above a convex bone, with numerous minute per¬ forations, the orifices of short canals. This is the su¬ perior turbinated or spongy bone. Below, and a little to the external side, is a small groove, separated by a thin plate from a larger cavity, which is the superior meatus, leading into the posterior ethmoid cells. Below this, again, is the osseous plate, with perforated edges turned on itself from within outwards, so that its convex side is towards its fellow, and its concavity is below and laterally, and separated by another thin plate from the lower mar¬ gin of the ossa plana. This is the middle turbinated bone, the longitudinal cavity of which communicates with the lower or nasal surface of the bone, and is bounded on its outer margin by the lower margins of the ossa plana, where they are articulated with the inner margin of the orbitar plate of the maxillary bone. The anterior defi¬ ciency of the ossa plana is occupied by the lacrymal bones. The internal surface of these bones generally is cover¬ ed by a thin fibro-mucous membrane, partaking of the characters of periosteum at its attached, and of mucous membrane at its free surface. The ethmoid is articulated with the frontal bone, the sphenoid, the superior maxillary bones, the nasal, the lacrymal, the palate bones, the inferior turbinated bones, and the vomer, at the parts already indicated. In structure the component plates are compact, unless at the crista galli, which contains some cancellated tissue, and the middle and superior turbinated bones, which seem less dense than the horizontal plate. The ethmoid bone consists in the foetus of loose, soft, brown-coloured substance, contained in a thick vascular membrane, and disposed in the cubical shape, but with¬ out the complicated arrangement of convoluted plates by which it is afterwards distinguished. Into this the ner¬ vous fibrils penetrate, and are observed to be ramified. This continues at least four or five months after birth, when these fibrils become surrounded with compact bone deposited in their interstices, and in this manner the per¬ forated plate is formed by deposition round the nerves. About the same time, on the mesial plane is observed a vertical plate, which gradually becomes condensed into solid bone, in the shape of the crista galli and middle par¬ tition. Soon after, as the bone increases in size, excava¬ tions are formed, and the soft uniform substance is remov¬ ed, while plates of thin but solid bone interposed between thick vascular membranes are observed to be formed. The plates, which are slightly convoluted, become thinner and more solid, and are at length moulded into the supe¬ rior and middle turbinated bones. The ethmoid is gene¬ rally complete about eighteen months after birth; and about the second year its different component parts may be recognised. The holes of the perforated plate are, how¬ ever, larger and more numerous at this age than after¬ wards. The minute grooves (canaliculi,) described by Scar¬ pa, in the lateral portions, are also more distinct and larger than subsequently. It ossifies therefore in four points; ANATOMY. Special one for the horizontal plate, one for the vertical, and one Anatomy.for each lateral mass. The sphenoid, wedge-like or cuneiform bone (os cunei- n In forme, os sphenoides, Kprjvoubn;)—a symmetrical bone, of a 111)11 )0rie' very irregular and complicated shape, wedged as it were between the bones of the scull, may be distinguished into cerebral or superior, and anterior-inferior or external sur¬ faces. By the ancient anatomists it was compared to a bat with the wings expanded, and is by them distinguish¬ ed into a body and wings, great and small. (Fig. 4.) The cerebral surface, covered by the dura mater, is su¬ perior, and forms part of the internal base of the scull. It may be distinguished into four parts; the middle, the upper anterior, and two lateral. The middle consists of a smooth surface, on which lie the olfacient or first pair; a transverse groove for the commissure of the optic nerves ; a transverse eminence named the olivary (processus oliva- ris); a deep quadrilateral pit in which is contained the pituitary gland, named the Turkish saddle (sella Tur¬ cica, ephippium, fossa pituitaria), with a slight groove on each side for the transit of the sixth pair of nerves, and bounded behind by an elevated eminence, with two pro¬ cesses, named the posterior clinoid or couch-like process¬ es. The sides of the sella Turcica, especially before and behind, present generally a pit, in which is lodged part of the carotid artery. The anterior serrated margin of this surface is articulated with the ethmoid bone; the poste¬ rior with the cuneiform process of the occipital bone. The upper anterior portions consist of two triangular spaces, united to the middle by their base. This surface, which corresponds to the anterior lobes, is bounded before by a serrated margin articulated with the frontal bone, behind by a smooth curved margin, which corresponds to the Sylvian fissure, and marks the separation of the ante¬ rior and posterior cerebral lobes. This arch, which may be named the sphenoidal, terminates before in a sharp process, named the ensiform, articulated with the frontal bone, and behind in a similar though smooth process named the anterior clinoid. Anterior to this, and between it and the olivary process, is the optic hole (foramen op- ticum), for the transmission of the optic nerves on each side. Behind this hole, and on each side of the olivary process, is the groove in which the internal carotid is lodg¬ ed. The triangular surfaces now described are commonly named the small wings (alee minores sive superiores), or the wings of Ingrassias. (Fig. 4, a, a.) The lateral surfaces are concave, marked with cerebral depressions and vascular grooves, four-sided, low behind, but rising to an angular peak before, and are commonly named the large wings (alee majores, alee medice, Soemm.) (A, A.) From the small wing of Ingrassias it is separated by a longitudinal fissure, extending obliquely from the sides of the sella Turcica upwards and laterally. Through this opening, which is large below and narrow above, and is va¬ riously named the superior orbitar fissure, the sphenoidal fissure (foramen lacerum superius et anterius, 1,1), pass the third pair or oculo-muscular nerves, the fourth or pathetic, the first or ophthalmic branch of the fifth, and the sixth or abductor nerves, the optic vein, and a branch of the lacrymal artery. Behind, and a little to the outside of the sphenoidal fissure, is the round or superior maxillary hole (foramen rotundum, r, r), for the transmission of the second or superior maxillary branch of the fifth pair ; and still more posterior and laterally the elliptical hole (foramen ovale), for the transmission of the third or interior maxillary branch of the fifth pair. This part of the large wing ter¬ minates behind in an angular process named the spinous, articulated with the petrous portion of the temporal bone, and in which is seen the spinous hole (foranmi spinosum), YOL. in. 17 through which a branch of the external carotid, the middle Special meningeal artery (arteria durce matris media, maxima), Anatomy, enters the cranium to be distributed on the dura mater, The lateral surfaces terminate before in an elevated re- ^ ^ sphe- cm ved peak, surmounted by a triangular surface mostly n°U >oru ‘ seriated, but smooth behind, articulated with a similar surface of the fiontal bone \ laterally in a concave serrated margin articulated with the convex serrated margin of the temporal bone; and behind in a smooth margin, which, with a similar one of the pyramidal portion of the tempo¬ ral bone, forms the anterior fissure of the base of the cranium (foramen lacerum anterius in hasi cranii.) The anterior inferior surface presents several distinct regions. On the mesial plane, at right angles to the ser¬ rated margin, is a vertical crest or spine, which terminates below in a process denominated therefore the azygos or rostrum, (of) The upper crest is articulated with the ver¬ tical plate of the ethmoid bone, the lower with the fissure of the vomer. On each side the bone is convex, from the swelling of the sphenoidal sinuses, into which may be seen a small opening, which, however, is nearly closed by an osseous plate, variable in shape, named by Bertin the sphenoidal turbinated bone. The interior of the sinuses is parted into two halves by a middle plate, corresponding to the external crest. On each side of this middle portion is the outer surface of the small wings, forming part of the orbit penetrated by the optic hole, to the circum¬ ference of which are attached the levator palpehrce superi- oris and levator oculi above, the depressor oculi below, the adductor within, the abductor without, and the superiorobli- que (trochlearis) between the two last. Between the mar¬ gins of the small and great wings is the outer orifice of the sphenoidal fissure ; and on the other side of this is the orbitar surface, hollow, bounded above by the serrated margin of the triangular area, without by that of the malar process, and below by a smooth ridge, which, with the posterior one of the superior maxillary bone, forms the spheno-maxillary fissure. Immediately between this is the external orifice of the superior maxillary hole. Ex¬ ternal to the malar serrated edge is the zygomato-tempo- ral surface, hollow, inclosed within three curvilinear serrat¬ ed margins and two rounded ones, and parted into two por¬ tions, the temporal and zygomatic, by an elevated ridge, to which are attached aponeurotic slips of the temporal muscle. Below this transverse crest is a concave surface, lost in the external pterygoid process, and forming part of the zygomatic fossa, terminating, like the similar part of the large wing, in the spinous process, and presenting first the elliptical, and then the spinous hole. The rest of the outer surface of the sphenoid bone terminates in two prominent bony plates, the one exter¬ nal, thin, and flat, the other internal, thicker, and more pointed, named the pterygoid or wing-like. These pro¬ cesses rise almost at right angles to the plane of the posterior part of the lateral wings by a thick prismatic piece of bone, common at first to both. Soon, however, they become distinct, especially behind. The external plate, which is thin, broad, and sharp, rises from the lateral por¬ tion between the round and oval hole, and, with its plane turned obliquely outwards, terminates in an end round below and before, sharp behind, (b, b.) To the outside of this plate, which is irregularly rough, with part of the zygo¬ matic fossa, is attached the external pterygoid muscle. The inside of the external plate is concave, and forms, with the internal, part of the pterygoid fossa, in which are lodged the internal pterygoid muscle and the external peristaphy- linus. The internal pterygoid process, rising on the inside, narrower and more curved, terminates in a bent point nam¬ ed the unciform or hook-like process (c, c), over which in a 18 ANATOMY. Special peculiar groove moves the tendon of the external peristaphy- Anatomy. Unus. The base of the external process generally presents longitudinal superficial depression named the navicular, noid bone" ®etween external and internal is left a triangular space, which is completed by the pyramidal portion of the palate bone. The base of the internal pterygoid process is pene¬ trated by the Vidian canal (canalis Vidianus), larger be¬ fore than behind, through which is reflected the posterior twig of the spheno-palatine ganglion, sometimes named the Vidian nerve (Plate X. fig. 2), to join the sixth at its connection with the great sympathetic, with some blood¬ vessels. The posterior part of the body of the sphenoid bone presents a quadrilateral surface of some extent, rough, cartilaginous, and sometimes excavated into small cells, for articulations with the cuneiform or basilar process of the occipital bone. In the young subject this surface is soft and cartilaginous ; but as age advances it becomes more solid, and is at length inseparably ossified with the occipital bone. From this circumstance Soemmering de¬ scribes the sphenoid and occipital as one bone, under the name of spheno-occipital ; a method in which he has been followed by Meckel. The bone, however, is so compli¬ cated in shape and the arrangement of its parts, that it is perhaps more intelligible to describe it separately. The sphenoid bone is articulated with all the bones of the scull at the points already indicated, and with the following bones of the face—the malar, the palate bones, and the vomer, sometimes with the superior maxillary. It consists, when fully formed, chiefly of compact bone; for the plates even of its cells, though thin, are compact and firm bone, and its general density is considerable. In the foetus the sphenoid bone, after remaining carti¬ laginous till the third month, begins to ossify in the lateral portion, near the roots of the pterygoid processes. Two other points of ossification appear on the large wings, and, coalescing with those already formed, constitute a single mass on each side for each lateral portion. About the same time the body in the sella Turcica begins to be formed; and shortly after the small wings are formed se¬ parately, and coalesce, first with each other, and then with the body. In the fifth month the bone has the same figure which it retains thi’ough life, but the extremities of the wings are soft and cartilaginous; the body of the bone is uniform, loose, bony matter ; the holes are large and imperfect; the optic hole is triangular; the inferior maxil¬ lary hole and the spinous are incomplete behind—some¬ times the latter is not formed; and the Vidian canal is a mere fissure between the base of the external and internal pterygoid processes. The bone at this time consists of five portions, one for each small wing, one for each large wing, and one for the body of the bone. At the period of birth, though these parts are still separable, in general the small wings become united with the body, and the bone thus consists of three pieces. Eventually, by the union of the two large wings with the sides of the body, the bone is consolidated into one portion, the optic foramen is rounded, the oval hole completed, and the Vidian fissure is at the same time converted into a canal. In this state the sphenoid continues for several years, growing in every direction, and diminishing the size of its several apertures ; till, about the age of puberty, the body becomes excavat¬ ed into two lateral cavities with compact walls, separated by middle partitions. These are the sphenoidal sinuses, the formation of which is generally simultaneous with the completion of the bone in all its parts. The occipi- The occipital bone (os occipitis, os prorce), symmetri- tal bone, cal, of a rhomboidal or trapezoidal shape, placed on the median line, occupying the posterior inferior region of the scull, may be distinguished into three parts, the occipital Special bone proper, the condyloid processes, and its cuneiform or Anatomy, basilar process. It presents two surfaces, an external or occipital, and an internal or cerebral. -taj The external surface is convex and smooth above the middle, where it is covered by pericranium and the tendi¬ nous fascia of the occipito-frontal muscle. Nearly in the middle the bone is elevated into an irregularly triangular eminence named the occipital protuberance (tuber occipi¬ tis), the size and shape of which vary according to the energy of the muscles connected with the strong fibrous fascia named the cervical ligament. When most strongly marked, the apex of the protuberance to which the trape¬ zius, by means of the ligament now mentioned, is fixed, is prominent downwards, and occasionally incurvated or unciform. From this prominence a line may be traced, obscurely at first, distinctly below, descending to the great aperture (foramen magnum), for the transmission of the spinal chord. To this ridge or crest (crista occipitis), which is not always exactly in the middle, a fibrous fascia of great strength is attached, from the protuberance to the aperture, giving support and attachment to the muscles on each side, and named the posterior cervical ligament (ligamentum cervicis, ligamentum nuchce). On each side of this ridge the surface is marked by various irregulari¬ ties, the effect of muscular impressions. A semicircular ridge, extending from the protuberance on each side to the margins, where it joins a similar ridge on the temporal bone, and named the superior semi¬ circular, gives attachment above to the occipital part of the epicranius, the lateral parts of the trapezius below, and at its marginal end to that of the sterno-mastoid. When the crest begins to be distinct, a similar ridge pro¬ ceeds in a semicircular direction to the margins of the bone, where it becomes more elevated, and occasionally changes its direction by a slight bend dowmvards and for¬ wards. To the space between these two lines, which is rough and irregular, the complexus, and part of the rectus capitis posticus major, are attached within, and the sple- nius capitis without; while the rectus capitis posticus ma¬ jor and minor, and the obliquus capitis superior, are in¬ serted by a strong fascia into the superior semicircular line. (Plate XXIV. fig. 6.) The lower region of the bone presents the verte¬ bral aperture, generally oval, with the large diameter an- tero-posterior, sometimes circular, occasionally rhomboidal or lozenge-shaped. At its anterior half are the condyloid processes, tipped with cartilage and synovial membrane, elliptical in shape, converging forwards, and parted by a sinuosity in the posterior part of the cuneiform process. By this opening the spinal chord with its membranes, and the spinal nerves, pass outwards, and the vertebral arteries enter the cranium. The posterior extremity of the condy¬ loid processes is bounded by a depression, containing generally a small hole, sometimes two, for the transit of vessels not constant; externally is a rough surface, for the attachment of the rectus capitis lateralis; and above is the anterior condyloid hole, for the transmission of the twelfth cerebral or hypoglossal nerve. The portion of bone anterior to the great aperture is the cuneiform process, the outer surface of which is de¬ pressed behind for the insertion of the recti capitis interni majores and minores ; but smooth before, where it is co¬ vered by the mucous membrane of the pharynx. The internal or cerebral surface, which is concave, is divided more or less regularly into four compartments, in the following manner. From the apex descends a groove nearly in the median line, though generally inclining a little to the right, to near the middle between the apex ANATOMY. 19 Special and upper margin of the great aperture, where it makes a Anatomy, rectangular turn to the right, leaving in the middle an ' elevated eminence, on the other side of which a simi- Tlie occi- ]ar groove> though always smaller, proceeds to the op- pital bone. p0Sjte margin 0f the bone, while from the same point descends an elevated ridge, more or less acuminated, to within half an inch of the great aperture. This arrange¬ ment produces in the inner surface of the occipital bone a cruciform appearance, which is occasionally named the spina cruciata, while the compartments are distinguished as superior and inferior right and left occipital fossce. The rectangular groove, which is the continuation of the sagittal, formed in the inner surface of the parietal bones, contains first the lower part of the superior longitudinal sinus, then the lateral sinus, the plates of the dura mater being fixed to the lateral ridges on each side. The groove on the left side contains the left lateral sinus; and to the central tubercle and ridge thv falx of the cerebellum is at¬ tached. In the two upper compartments, which are much marked by cerebral eminences and depressions, the pos¬ terior cerebral lobes are lodged, while the cerebellic lobes are contained in the rnferior compartments. (Fig. 7.) On each side of the large aperture is seen a short seg¬ ment of a broad circular furrow, which terminates on the margin of the bone in a smooth sinuous depression. The first part is the termination of the lateral groove, contain¬ ing the end of the lateral sinus; the second, the sigmoid notch, forms, with a similar one on the temporal bone, the jugular hole (foramen lacerum posterius in basi cranii, fora¬ men jugulare, incisura jugularis'), for the commencement of the jugular vein, the glosso-pharyngeal nerve, the nervus vagus, and the accessory nerve. Occasionally there is a proper notch for the nervus vagus in the anterior part, and occasionally one for the glosso-pharyngeal. Anterior to the large aperture is the inner surface of the cuneiform process, concave transversely for lodging the medulla oblongata, before it quits the cavity of the cra¬ nium (fossa basilaris), marked by a groove at the sides for the inferior petrous sinuses, and terminating abruptly in a broad quadrilateral surface incrusted with cartilage, for articulation with the posterior part of the sphenoid bone. The margins of the occipital bone posterior to the in¬ ferior lateral groove are serrated for articulation by su¬ ture with the parietal and temporal bones. The upper margins form a salient angle, nearly rectangular, for articu¬ lation with the re-entrant angle formed by the two pa¬ rietal bones. The sides of this angle, however, vary in direction from the presence or absence of Wormian bones (ossa Wormiana, triquetra). Another salient angle, but al¬ ways obtuse, is formed opposite the superior lateral grooves, for articulation with the re-entrant angle formed by the parietal and temporal bones of each side. A third angle is formed by the jugular eminence, an elevated process placed between the inferior lateral groove and the jugular notch, and which is tipped with cartilage for articulation with a corresponding surface of the pyramidal portion of the temporal bone. Anterior to the jugular notch the margin of the bone is smooth, but articulates by fibro- cartilage with the posterior surface of the temporal pyra¬ mid, leaving a small space unarticulated between the an¬ terior extremities of both bones, which form a common aperture. The occipital bone is thick along the crucial spine, the tubercles, and at the condyloid process; but thin in the centre of the four occipital fossas, at which the external and internal tables are united with little or no diploe, and are not unfrequently translucent. The cuneiform process is cancellated. In the foetus it consists of four pieces, one for the occi- Special pital bone proper, one for each condyloid portion, and one Anatomy, for the basilar process. The ossification of the occipital portion commences near its middle, corresponding to a bone point above the occipital protuberance, and extends by radiating fibres all round to the margins of the bone. At this time the occipital portion has the shape ofacardium; and the apex not being formed, a space is left through which the brain is felt pulsating, named the posterior fon- tanelle. About the same time ossification appears in two quadrilateral portions on each side of the large aperture, and in an oblong parallelogram anterior to it. Though these enlarge and approach each other, at the period of birth the apex is still incomplete, and the posterior fonta- nelle is open; and even at the inferior angles of the oc¬ cipital portion, where it joins the condyloid portions, a space of the same kind is left on each side. After birth, as ossification advances rapidly, the apex of the occipital portion is gradually enlarged, the Wormian bones on each side are formed, and the condjdoid and basilar portions uniting with the occipital, the bone is consolidated about the third or fourth year. The traces of the lines of union may sometimes be recognised so late as the seventh year. The occipital bone is articulated immovably by its mar¬ gins with the sphenoid bone, the two parietal, and the two temporal bones ; movably by its condyles with the atlas. It is also connected with the second vertebra by means of a ligament, which passes from the odontoid process to the inner margins of the condyloid processes. The parietal bones (ossa verticis, ossa bregmatis, ossa The parie- parietalia), two bones united with each other on the tal bones, mesial line, are quadrilateral, quadrangular, convex exter¬ nally, concave internally, occupying the upper, middle, and lateral parts of the cranium. (Plate XXVI. fig. 4 and 5.) The external convex surface, which is covered by the epicranius above and temporal muscle below, pre¬ sents above and behind a hole for an artery and vein, va¬ riable however in position and existence; in the middle the parietal eminence, prominent in youth, indistinct in advanced age ; and somewhere between its middle and lower margin a curvilinear ridge, the continuation of that on the frontal bone, and terminating near the lower angle of the parietal for the attachment of the temporal fascia, below which the bone is covered by the temporal muscle. The internal concave surface, lined by the dura mater, is marked by digital eminences and depressions corre¬ sponding to those of the cerebral convolutions. The su¬ perior edge is marked by a half-groove, which, with that of the opposite bone, constitutes the sagittal for lodging the superior longitudinal sinus ; within this, depressions more or less deep, corresponding to the granules of Pacchioni; towards the centre the parietal pit, corresponding to the eminence of the external surface ; and ascending from the inferior anterior angle arborescent grooves, in which the large meningeal artery is lodged, (m, m.) Parts of these grooves are occasionally converted into canals by the growth of bone over their margins. The parietal bone is bounded by four margins. By the superior, which is serrated, it unites on the mesial plane with the opposite bone, forming the sagittal suture; by the anterior or coronal, also serrated, it is articulated firm¬ ly with the frontal bone, forming the coronal suture ; and the posterior, also serrated, forms with the posterior mar¬ gin of the corresponding bone a re-entrant angle, in which the occipital, occasionally with Wormian bones, is articu¬ lated. The lower margin alone, which is a concave cur¬ vature, is obliquely acuminated before, acuminated and serrated in the middle for imbrication with the temporal 20 A N A T Special bone, and serrated behind for articulation with the upper Anatomy, margin of the mastoid process. These margins form by union four angles, an anterior t-'l bones6" and Poster>or superior, and an anterior and posterior infe¬ rior, of which the most important is the anterior inferior, by reason of its presenting the origin of the meningeal groove on its internal surface. The parietal bone, consist¬ ing of an external and internal table, with interposed di- ploe, is thin, especially below its middle ; and the diploe is small, and in some points obliterated. It is ossified from one point, commencing at the protuberance, and radiating all round to the margins. Previous, and some time subse¬ quent to birth, its mesial margin and anterior and supe¬ rior angle are not formed; and the brain is here covered by dura mater, pericranium, and integuments only, forming, as already mentioned, the bregma, or anterior fontanelle. By the completion of the bones, however, the margins and angles meet, and the fontanelle is closed. This is generally effected in the course of the second year. The tem- The temporal bones {ossa temporum), rather irregular poral bones, in shape, are placed on each side at the lateral and infe¬ rior parts of the cranium. Each bone presents an external or auricular surface, an internal or cerebral, and a circumference. The external or auricular surface presents, above and before, a large convex surface, part of the temporal fossa lodging part of the temporal muscle ; before, the zygomatic process, long, pointed, and terminating in a serrated ex¬ tremity, where it is united with the malar bone to form the zrjgoma (fig. 2, z), to the upper surface of which the temporal fascia is attached, to the lower the masseter mus¬ cle ; behind, a flat surface of an irregularly rounded shape, terminating before in the mastoid process (processus mam- millaris, mastoideus, m), and behind in a serrated margin, which unites with the occipital bone. Between the mas¬ toid process and the serrated margin behind is a rough surface for the splenius, small complexus, and sterno-mas- toid ; and below is a pit, in which the origin of the digas¬ tric muscle (biventer maxillae) is lodged. The zygomatic process is connected to the temporal bone by two roots, one of which, anterior, inferior, and transverse (processus transversus), forms the anterior brim of the glenoid or articular cavity, in which the condyle of the inferior jaw is lodged; the other, superior and poste¬ rior, forms first the external and then the posterior brim of the same cavity. Behind this posterior brim is an irregu¬ lar fissure termed the glenoid (Jissura Glasseri), which in¬ dicates the original line of separation between the superior or squamous and the inferior or pyramidal portion of the bone, and through which pass the tendon of the anterior muscle of the malleus, some vessels, and a nervous twig named chorda tympani. In the angle between the mastoid and zygomatic process is an elliptical opening from five to six lines in diameter, leading into a cylindrical cavity, the direction of which is obliquely forwards. This orifice, which is the external ear- hole (^meatus externus, o), leads into the tympanal cavity, from which it is separated, in the recent subject, by a thin membrane only (membrana tympani). The three lower thirds of this orifice are formed by a distinct bony ring, which is rough, and perforated by holes for the insertion of the cartilages of the external ear. On the outside of the lower part of this bony ring is a strong process, vary¬ ing from half an inch to 12 lines in length, nearly round, but terminating in a sharp point, and therefore, from its resemblance to the style of the ancients, named the sty¬ loid process. (^J tissimus dorsi, passing over its lower angle, binds it down.™°™£ The scapula consists chiefly of compact bone, with ^ little cancellated matter interposed. In the subscapular fossa this becomes completely absorbed, rendering the bone thin and translucent, sometimes perforated. The spine, processes, and angles contain cancellated matter. It is formed from one part for the body of the bone, with epiphyses for the coracoid process and the margins. Nutritious holes are generally found in the angle formed by the spine with the body, and in the axillary margin. The collar bone or clavicle is a cylindrical bone, alter-Clavicle or nately incurvated like an f placed at the upper part of the collar bone, chest, between the sternum and acromion of the scapula. It has therefore two extremities, a sternal and acromial, with intermediate body. The sternal end is triangular, cartilaginous, concave and convex in opposite directions, surrounded by ligamentous insertions. The acromial end is flattened and recurved, presenting a lunated surface for articulation with the acromion. The body, with the shape of a triangular prism at the sternal end, is rounded above for the attachment of the cla¬ vicular portion of the sterno-mastoid muscle, and presents below a rough surface for the costo-clavicular ligament, and a sinuated line for the subclavian muscle. Towards the acromial end, where it is flattened above and below, it presents before, a surface for the attachment of the large pectoral and deltoid muscles; behind, another for the cucullaris; and below, a prominent oblique crest for the coraco-clavicular ligaments. Compact in the middle, and cancellated at its extremi¬ ties, the clavicle is developed from a single point. The arm-bone or humerus (os brachii) is a long cylin-Thc arm- drical bone, divided into head or scapular end, cubital orbone' lower end, and shaft or body. The head presents three eminences, the articular head, the anterior tuberosity, and the external tuberosity. The first, which is hemispherical, incrusted by cartilage and sy¬ novial membrane, with the axis oblique to that of the bone, and articulating with the glenoid cavity of the sca¬ pula, is separated from the bone by a narrow depressed line named the x\ec\t(collum), in which is fixed the margin of the scapulo-humeral capsular ligament. The second is a small, pointed, sometimes bifid eminence, to which the tendon of the subscapularis is attached. In the external tuberosity are distinguished three facettes, to the upper of which the tendon of the supraspinatus, to the middle that of the infra¬ spinatus, and to the posterior the tendon of the teres minor, are inserted. Between the anterior and the external tube¬ rosity is a longitudinal groove named the bicipital, for the transit of the long head of the biceps flexor. The cubital or lower extremity is flattened transversely, and moulded into different eminences and depressions. Internally is the inner or ulnar condyle, large and pro¬ minent, for the attachment of the internal lateral liga¬ ment, and a tendon common to the pronator teres, palmaris longus, flexor sublimis, radialis internus, and ulnaris inter- nus. Externally is the outer or radial condyle, to which are attached the external lateral ligament, and the ten¬ don common to the supinators and extensors, viz. supina¬ tor longus and brevis, anconeus, radialis externus, ulnaris externus, and extensor communis. Between these is an articular surface covered by cartilage, moulded into the small head which moves in the cavity of the radius, a groove corresponding to the margin of the latter; the semicircular crest interposed between theratfmsand w/wcz, 32 ANATOMY. Special another groove rather larger, in which the prominence of Anatomy, the sigmoid cavity is lodged ; and the trochlear or pulley- )!|^~v''V/like eminence, which is received in the internal part of the extrerniC s‘gmo‘d cavity, and the size of which renders the inner side ties. °f the humerus larger than the outer, and gives it the ob¬ lique direction when placed on the horizontal plane. Be¬ fore is a superficial pit for the coronoid process of the ulna during flexion of the fore-arm, and behind is a deep one for receiving the olecranon during extension. The shaft is not cylindrical, but prismatic, consisting of three surfaces, bounded by an equal number of lines. The first line, which descends from the anterior tuberosity, and, winding to the side, terminates on the ulnar condyle, is anterior above, where the tendons of the latissimus dorsi and teres major, and the short head of the triceps, are at¬ tached, but becomes internal-latei'al below, where an in¬ termuscular aponeurosis is fixed. The second, which de¬ scends from the fore-part of the large tuberosity to the anterior articular pit, is anterior throughout, and gives at¬ tachment above to the large pectoral muscle, at the mid¬ dle to the deltoid, and below to the brachialis externus. The third line, which descends from the back of the great tuberosity to the external or radial condyle, is posterior above, where the triceps is fixed, but external below, where the intermuscular aponeurosis and the supinator longus are attached. Of the three surfaces, the first, which is anterior and in¬ ternal, presents above, the bicipital groove, covered by pe¬ riosteum and synovial membrane for the long head of the biceps ; in the middle, the medullary hole and insertion of the coraco-brachialis ; and below, a surface covered by part of the brachialis internus. The second, which is external, is covered above by the deltoid, below by the rest of the brachialis, and in the middle presents the deltoid tube¬ rosity for the insertion of its tendon, and below this an oblique sinuosity traversed by the radial nerve. The third, which is posterior, gives attachment above to the triceps, and below is merely covered by that muscle. The humerus, cancellated at its extremities, and com¬ pact in the shaft, is ossified in three parts; one for the latter, and one for each of the former. The ulna. The ulna or cubit (cubitus) is a long bone placed at the inside of the fore-arm, articulated above with the humerus, below with the carpus or wrist, and laterally with the radius. Its superior or humeral extremity consists of two eminences, and an intermediate semilunar or crescentic cavity. The first is a large head named the olecranon (ojXsvtjs jcsavov, ulnae caput, or elbow; processus anconeus, ancon) ; irregular above, with a small space behind, where the tendon of the triceps extensor is fixed; concave and cartilaginous before, where it forms part of the sigmoid cavity. The second is a broad, thin-edged process, prominent before, about half an inch below the olecra¬ non, the upper surface of which is cartilaginous, and completes the sigmoid cavity; the lower surface is rough for the brachialis internus, some fibres of t\\cpronator teres, the flexor sublimis, and the internal ligament of the hu- mero-cubital articulation. At the outside, and continuous with the sigmoid cavity, is a small semicircular cartila¬ ginous surface—the small semilunar—for articulating with the head of the radius. The lower or carpal extremity presents a cartilaginous surface, shaped like a circular sector, the circular margin being bent upwards, so as to form a circular surface for the inner articular surface of the radius, while from the centre of its radii arises a pointed process named the sty¬ loid, to the tip of which the external ligament of the ra¬ dio-carpal articulation is fixed. Between the styloid pro¬ cess and sectorial surface is a depression, to which is fixed the fibro-cartilage of the joint; and behind and without Sppoia) the styloid process is a longitudinal groove for the motion Anatomy, of the tendon of the ulnaris externus. The shaft has the shape of a trilateral prism, except at the lower extremity, where it becomes cylindrical. Oft;es the three lines by which the surfaces are bounded, the external or radial, which is strongly marked, and sharp at the middle, extends from the posterior tip of the small sigmoid cavity to about two inches above the lower end, and gives attachment to the interosseous ligament. The second, internal or ulnar, which is obtuse, descends from the inner edge of the coronoid process to the inside of the styloid, and gives attachment above and in the middle to the flexor profundus, and below to the pronator quadratus. The third, posterior, obtuse above and below, sharp in the middle, extends from the olecranon to the outside of the styloid process, and gives attachment to an aponeurosis. Of the surfaces inclosed by these lines, to the anterior, which is concave, and contains the medullary hole, the flexor sublimis is attached above, and the pronator quadra¬ tus below. The inner is covered above, where it is broad, by the flexor profundus, and below by the integuments. The posterior or radial is parted by a line into two spaces, to the larger of which are fixed the anconeus and ulnaris externus, and to the smaller the supinator brevis, extensores pollicis longus et brevis, the abductor pollicis, and extensor indicis. The radius is a long bone, rather shorter than the ulna, The ra- forming the outer bone of the fore-arm, articulated above dius. with the humerus, below with the carpus, and at the in¬ side with the ulna. The upper extremity consists of a circular cartilaginous head, concave for receiving the small head of the humerus, with a cartilaginous surface on its inner or ulnar side for articulating with the small sigmoid cavity of the ulna, and a rough one for the annular ligament on the outside. Be¬ low this the bone is contracted and forms the neck of the radius, and again swells before into a large rough promi¬ nent tubercle, to which the tendon of the biceps flexor is fixed, and which is therefore named the bicipital tube¬ rosity. The lower extremity, which is double the size, forms an extensive surface for articulation with the scaphoid and semilunar bones of the carpus, continuous on the ulnar side with a small cartilaginous surface for articulation with that of the ulna, bounded without by the styloid process, a rough triangular eminence, to which is fixed the exter¬ nal ligament, and bounded elsewhere by a rough margin for ligamentous insertions. The posterior part of this end presents two eminences inclosing a wide hollow, separat¬ ed by a small eminence into two grooves,—an inner or ulnar, large for the tendons of the extensor communis and the extensor proprius indicis, and an outer or radial for the extensor longus pollicis. Between the middle eminence and the styloid process are two other grooves,—the an¬ terior for the abductor magnus and the extensor brevis of the thumb, and the posterior for those of the radiates externi. The shaft or body, which is thin and round above, prismatic in the middle and below, presents three surfaces inclosed by an equal number of lines. Of the latter, the inner or ulnar descends from the inner margin of the bicipital tuberosity, sharp and prominent, to the small inner articular surface, and gives attachment to the inter¬ osseous ligament. To the outer, which descends from the outer margin of the tuberosity, obtuse, to the base of the styloid process, the flexor sublimis, pronator quad¬ ratus, and supinator longus are attached. The third, also obtuse, is indistinct to the second third of the bone, ANATOMY. Thoracic extremi- Speeial whence it proceeds to the middle tubercle of the carpal Anatomy, extremity. J The anterior surface, which is hollow above, presents the medullary hole and the attachment of the flexor longus pollicis below that of the pronator quadratus. The posterior, hollowed in the middle, corresponds to the supinator brevis, the extensors, and abductor pollicis, which are attached to it; and the common extensors, extensor proprius indicis, and extensor pollicis, by which it is sim¬ ply covered. The external surface, which is rounded, is covered above by the supinator brevis, in the middle by the pronator teres, which are attached to it; and below by the radial extensors (radiales externi), which merely glide over it. The ulna and radius consist of cancellated structure in the epiphyses, and compact inclosing cancelli in the diaphyses, and are each ossified in three points. These two bones are mutually connected by a broad web of periosteum continued from that of the bones, and named the interosseous ligament, the principal use of which is to enable the radius to roll laterally in the mo¬ tions of pronation and supination on the ulna, and to give attachment to muscles without adding to the weight of the fore-arm by intermediate bone. 33 The bones of the hand consist of those of the carpus, the metacarpus, and the phalanges. The carpal The carpus consists of eight short and irregular-shaped bones, arranged in two rows. Those of the first are the scaphoid or navicular (ps scaphoides, os naviculare), the semilunar {os lunatum), the cuneiform or trilateral {os triquetrum), and the pisiform or lenticular {os orbiculare, os pisiforme). Those of the second row are the trapezal {trapezium), the trapezoidal {os trapezoides), the large bone {os magnum, os capitatum), and the unciform bone {os unciforme, os hamatum). Of these bones, which it would be tedious to describe minutely, it is enough to say, that their names are intend¬ ed to indicate their shape; that they are connected mu- tually by cartilaginous surfaces, so as to allow the gliding motion only; and that, besides periosteum, they are in¬ vested by ligaments which maintain them in their posi¬ tion, and tend to strengthen and consolidate the wrist, as the basis of support for the hand and fingers. By the upper articular surface of the scaphoid and semilunar bones, the carpus is connected to the lower extremity of the radius; while the upper surface of the trilateral bone is contiguous to the fibro-cartilage of the radio-carpal articulation, and the upper surface of which is in contact with the lower articular surface of the ulna. The pisiform bone, which is attached to the anterior sur¬ face of the latter, and thus projects before the plane of the other bones into the hand, may be regarded as a sesamoid bone, which serves as a point of insertion to the tendons of the flexor carpi ulnaris above, the fibres of the adductor of the little finger below, and those of the anterior carpal ligament before. The inferior surface of the navicular bone is articulat¬ ed at once to the superior surfaces of the trapezium and trapezoides. The palmar or anterior surface of the for¬ mer presents a small groove, in which moves the tendon ot the flexor carpi radialis, bounded on the outside by the pyramidal process, to which the annular ligament is at¬ tached. The os magnum, which is articulated above with the semilunar bone, on the radial side with the scaphoid and trapezoidal, below with two metacarpal bones, and on the ulnar side with the unciform bone, is thus wedged firmly like a central base between the others, and contri¬ butes much to the solidity of the carpal articulations. The VOL. in. unciform, which is placed at the inside of the range, and Special is articulated above with the lunar and cuneiform, later- Anatom', ally with the scaphoid, and below with the two inner me- tacarpal bones, is distinguished by the unciform process Th»radc rising from its palmar surface, to which part of the renn' tor and flexor brevis minimi digiti and the annular liga¬ ment are attached, and which, stretched between this and the pyramidal process of the trapezium, form a species of arch over the flexor tendons. The carpal bones consist of cancellated tissue, invested by a thin pellicle of compact bone. In the fcetus and in¬ fant they are composed chiefly of brown-coloured, callous substance, homogeneous, but without the smallest trace of bone. Their penetration with this substance takes place about eighteen months or two years after birth. The metacarpus is usually said to consist of five bones. The meta- This is correct so far as situation goes; but one of these carpal bears little resemblance either in shape, connection, 0rbones- purpose with the other four. It appears, therefore, more natural to restrict the name of metacarpal to the four bones which support the digital phalanges, than to extend it to the thumb, the first bone of which is to be regarded as & phalanx only. The four metacarpal bones agree in having trapezoidal heads, cylindrical bodies with an elevated longitudinal line before, and rounded convex lower ends for moving on the concave articular surfaces of the phalanges. Besides the upper trapezoidal surfaces for articulating with the trapezoidal, large, and unciform bones, the lateral margins are provided with facettes, the first and fourth on one side only, the mutual, the second and third, on both, for articulation with each other. In this manner the me¬ tacarpal bone of the index finger is articulated above to the trapezoidal and large bone, and on the inside to the metacarpal bone of the middle finger; the latter is arti¬ culated above to the large bone, and on the one side to the index metacarpal bone, on the other to that of the ring finger; while the latter and the metacarpal bone of the little finger are articulated above to the unciform bone and to each other. The bodies of the metacarpal bones are slightly incur- vated before, and form a hollow which corresponds with the palm. In their intervals are contained the interossei muscles, the internal at the volar, the external at the dorsal surface. The anterior surface is covered by the flexor tendons, the lumbricales, and the palmar fascia. 1 he dorsal surface, which is convex in general, is covered by the extensor tendons. The index metacarpal bone has attached to its radial margin the first dorsal interosseus, to its ulnar, before, the first palmar interosseus, and behind the second dorsal in¬ terosseus; while to its upper anterior extremity the radialis internus is inserted, and to the same extremity behind the extensor radialis longior. To the second or middle metacarpal bone, besides the palmar fascia and the second and third interossei, the ad¬ ductor pollicis and flexor brevis are attached to the palmar surface; and the extenson' radialis brevior is inserted into its dorsal surface. The fourth or small metacarpal bone, besides the pal¬ mar fascia and the third palmar and fourth dorsal interos¬ seus, gives insertion by its dorsal surface to the extensor carpi ulnaris. I he phalanges or bones of the fingers are fifteen small longitudinal bones placed vertically on each other, three to each finger; or forming ranges distinguished into meta¬ carpal, middle, and unguinal, the first row being the long¬ est, the second shorter, and the third or unguinal the shortest. E 34 Special Anatomy. The pha¬ langes. ANATOMY. The metacarpal ■phalanges agree in having the upper extremities shaped like rounded cubes, with concave car¬ tilaginous surfaces for receiving the lower extremities of the metacarpal bones, and tubercular sides for the attach¬ ment of the lateral ligaments. The upper ends of the middle and unguinal are moulded into two cartilaginous cavities with an intermediate ridge, with lateral tubercles for the lateral ligaments. The lower extremities of the me¬ tacarpal and middle phalanges, which are smaller than t le upper, are rounded and separated by a sma.ll groove into two condyles, which are received into the cavities of the up¬ per ends." The lower extremities of the unguinal phalanges, which terminate the fingers, are flattened antero-posterior- ly, and moulded into crescentic tips (JunulcB) transversely. The bodies of the metacarpal and middle phalanges are convex behind, and have a surface flat before, bounded on each side by a sharp marginal line, and taper gradually from above downwards. Those of the unguinal phalanges, except¬ ing that of the thumb, are convex before as well as behind. The palmar surface of the metacarpal phalanges is covered by the flexor tendons, which in the superficial muscle are inserted into the anterior and upper part of the middle phalanx, while those of the deep-seated flexor are inserted into the upper anterior part of the unguinal phalanx. Ihe first phalanx of the thumb, which is generally considere as a metacarpal bone, has the abductor magnus inserted into its upper extremity, and the opponens and flexor brevis into its body. The dorsal surfaces are covered by the ex¬ tensor tendons, which, with those of the lumbricales and interossei, are inserted into the middle phalanges. The metacarpal and phalangeal bones are compact, with cancellated extremities, and are ossified in three points. The bones now enumerated are connected so as to ad¬ mit of motion to various extents. The humerus, articulat¬ ed with the glenoid cavity of the scapula by a capsular ligament, while the long head ot the biceps^ selves the purpose of a round ligament, admits of motion in every direction,—flexion, extension, abduction, adduction, cir¬ cumduction, and rotation. The humero-cubital articulation, which is secured by two lateral ligaments, admits ot ex¬ tension and flexion only; but in any position of the ulna in relation to the humerus, the radius rolls on the former, so as to produce those motions of the wrist and hand which are denominated pronation or internal rotation, and supi¬ nation or external rotation. The carpal bones are articulated chiefly with the radius, so as to admit of flexion and extension, adduction and ab¬ duction, and even some degree of circumduction and ro¬ tation. The metacarpal bones are limited in motion. The metacarpal phalanges admit of flexion and extension, ab¬ duction and adduction, circumduction and rotation ; while those of the middle and unguinal range are confined to flexion and extension. The precision, nevertheless, ot which these motions are susceptible, with the numerous modifications which they undergo in combination with the opposable powers of the thumb, and the nicety and deli¬ cacy of tact inherent in the skin of the fingers, are the means from which the human hand derives its remarkable aptitude for all the mechanical arts, and all operations requiring manual dexterity. By the combination almost endless of a number of simple motions, so many complex motions are produced, that it is difficult to set limits to the degree of perfection which the hand and fingers, as an organ of prehension, may attain. The bones § 7- ^ Bones °fthe Pelvic Extremities. The bones proper to the lower or pelvic extremities mities. are, the thigh-bone (Jemur), the shin-bone {tibia), and Connec¬ tions. Shoulder- joint. Elbow- joint. Wrist and finger joints. leg-bone {Jibula); with the knee-pan {rotula,patella), seven Special tarsal bones, four metatarsal bones, and 15 phalanges.. The thigh-bone {femur, os femoris) is the largest, thick-The ^ est, strongest, and heaviest bone of the skeleton. bone. The upper or iliac extremity consists of a head, neck, and two tuberosities named trochanters. The head is globular, incrusted by cartilage and synovial membrane, unless at its internal point, where there is an irregular de¬ pression for the insertion of the round ligament, and is lodged in the cotyloid cavity {acetabulum). It is situate internally in relation to the shaft; and its axis, which forms with that of the latter an obtuse angle, variable in extent according to age and sex, is represented by that of the neck, a contracted cylinder of bone, varying in length ac¬ cording to the same circumstances, flattened before and behind, presenting numerous vascular holes, and covered by fibrous slips and synovial membrane. The junction of the neck with the bone is marked by a large prominent body named the trochanter major {t), in which four surfaces may be recognised ; an external lateral, for the insertion of the glutceus medius, and the motion of the tendon, of the glutceus maximus; an internal with a pit, for the in¬ sertion of the tendon of the pyriformis, of the gemelli, and of the obturators; an anterior for the insertion of the ten¬ don of the glutceus minimus ; and a posterior for that of the quadratus femoris. At the union of the neck with the diaphysis below, and externally, is a conical eminence named the small trochanter (t), to which the united tendon of the psoas magnus and iliacus interims is fixed. The spaces between the trochanters before and behind are united by oblique rough lines, to which the femoral margin of the capsular ligament is attached, and the entire space within which is continuous with the articular cavity. The lower or tibial extremity, which is large, is moulded into two rounded eminences named condyles (xovtluXo/) (1, 2; a, b); the one internal, deeper, and larger than the external, separated by an antero-posterior depres¬ sion {fossa intercondylaris), and prominent and convex behind. Each condyle has an external and internal sur¬ face, while the articular one, which is incrusted by carti¬ lage and synovial membrane, is shaped something like a horse-shoe, incurvated upwards in the middle before, and behind on each side, with elevated irregular margins for the attachment of the articular capsule. The intercondylar depression before receives tbe upper part of the knee-pan (patella), while in the intercondylar cavity behind are lodged the fimbriated margins of the synovial membrane, with the femoral ends of the cross ligaments, the anterior of which is inserted into the inner surface of the external condyle, and the posterior into that of the internal con¬ dyle. The outer or fibular surface of the external condyle presents an eminence for the attachment of the external lateral ligament, and a depression below for that of the poplitceus. The outer or tibial surface of the internal condyle has a prominent tubercle, to which are fixed the internal lateral ligament and the tendon of the adductor magnus. In a pit above each condyle the heads ot the gemellus (gastrocnemius externus) are fixed. . The shaft or body, which approaches the cylindrical shape, is incurvated, with the convexity before, and the concavity behind (F, f). The anterior surface is uni¬ formly round, and covered by the crurceus, which is fixed above to the interval between the trochanters. The pos¬ terior surface presents a rough elevated line, descend¬ ing from the base of the large trochanter, meeting a simi- lar line descending from the small trochanter, and in¬ closing a triangular rough space, forming about the middle third of the bone a rough elevated Yme (linea aspera) (1), which again is parted into two, less distinct; one termi- ANATOMY. Special nating on the external, the other very faint on the inter- Anatoniy. nal condyle. To the upper part of the external line, where it is most prominent, the tendon of the glutceus maximus is inserted; next is the short head of the biceps ; and to the rest are fixed the fibres of the vastus externus. To the inner line the pectinams and adductor brevis are inserted above, and the vastus internus is attached below; while the adductor longus and magnus are fixed to its whole length, unless at one point, where it is interrupted about three inches above the condyle by a smooth sur¬ face, on which the femoral artery passes under the tendon of the adductor magnus, to continue its course between the condyles, where it becomes the popliteal artery. The femur, which is one of the most perfect examples of a long cylindrical bone, is compact in the diaphysis, with distinct medullary canal, and cancellated in the epi¬ physes. It is ossified in four portions; one for the dia¬ physis and neck, one for the two condyles, one for the head, and in general one for the trochanter major. The neck, which is short in early life, becomes long in adult age, and the body acquires its peculiar incurvation appa¬ rently from muscular action. In the female this incurva¬ tion is greater than in the male, and the neck forms a greater angle with the body. The knee- The knee-pan (rotula, patella) (p) is a short bone, shaped paa- like a heart, with the apex downward, convex and fibrous before, where it is covered by tendinous matter; flat above, where the rectus, the two vasti, and the crurceus, are inserted ; plane and concave behind, where it is covered by cartilage and synovial membrane, and separated into two unequal divisions by a middle ridge, forming the an¬ terior wall of the knee-joint, and applied by its superior half over the anterior intercondylar fossa. The lower apex is rough for the attachment of the inferior ligament; and to the margins are fixed those of the fibro-tendinous capsular, by which it is connected to the femur and tibia. The knee-pan, which has a peculiar cancellated struc¬ ture, invested by a thin plate of compact bone, is to be regarded partly as a sesamoid bone for the insertion of the common tendon of the four extensors of the leg, partly as an appendage or epiphysis to the superior part of the tibia, performing to that bone the same function which the olecranon does to the ulna. The shin- The tibia is a prismatic-shaped long bone, situate at the bone. inner and anterior region of the leg, with the femoral condyles above, the astragalus below, and the fibula on the external side. The head, upper or femoral end, is large., and of an ir¬ regular oval shape. It presents two slightly concave elliptical cartilaginous surfaces, with the long diameter antero-posterior, separated by a rough vascular space, large before and narrow behind. Of these elliptical sur¬ faces the external margin is most regular, and presents a crescentic or lunated mark for the attachment of the semi¬ lunar fibro-cartilages, which thus increase the concavity of the articular surfaces for the reception of the condyles. The inner or mesial margin of each is elevated into a curved peak, mutually separated by a depression. These eminences, which are jointly named the spine of the tibia, correspond in flexion and extension to the intercondylar fossa. Before is a triarcual surface, rough for the insertion of the anterior crucial ligament, and behind a notch for that of the posterior. The lateral circumference of the head, which is rough, and marked by vascular holes, pre¬ sents before a triangular surface, the upper half of which corresponds to the inner surface of the knee-pan, and is contained within the cavity of the joint; while the lower angular portion is convex for the insertion of the inferior patellar ligament, or the last insertion of the tendon of the rectus and vastus externus. The sides, which are rounded Special and prominent, are named respectively the external and in- Anatomy. ternal tuberosities, and give attachment to the external and internal lateral ligaments. To the back part of the inter¬ nal also the tendon of the semimembranosus is fixed (d), while that of the external presents a cartilaginous facette for the articulation of the head of the fibula (c). The lower or tarsal extremity, which is much smaller, is nearly quadrilateral, with a cartilaginous surface con¬ cave transversely, with elevated anterior and posterioi borders, and the internal raised into a vertical eminence named the inner ankle {malleolus internus) (f), to the apex of which the internal lateral ligament is fixed. This carti¬ laginous surface, which receives the head of the astragalus, is surrounded by a furrow, very distinct before, in which ligamentous fibres are inserted; while the external margin, which is broader than the internal, presents between two prominences a trilateral hollow, in which the tarsal end of the fibula is lodged. The anterior surface is covered by the tendons of the tibialis anticus and extensor pro- prius halhicis; and the posterior, behind the internal ankle, is marked by a groove for the tibialis posticus and flexor longus digitorum, and another for the flexor longus hallucis. The body or diaphysis, which is thick above, is prisma¬ tic, and presents three surfaces, bounded by the same number of lines. The first, which is anterior (crista), descends sharp and prominent from the anterior margin of the external tuberosity to the fore part of the internal ankle, and, though subcutaneous, gives attachment to the tibial aponeurosis and the tibialis anticus. To the ex¬ ternal, which is sharp, and descends from the posterior margin of the same tuberosity to the anterior tubercle of the lower end, the interosseous ligament is fixed. To the internal, which is obtuse, and rather rounded, and descends from the posterior part of the internal tuberosity to that of the inner ankle, the poplitceus above, and the second or inner head of the solceus, with the flexor longus digitorum, are attached. The surfaces bounded by these lines are internal, ex¬ ternal, and posterior. The first, which is convex, gives insertion above to the sartorius, gracilis, and semitendi- nosus, and is elsewhere covered by integuments only. The external is concave above, where the tibialis anticus is fixed; convex below, where it is covered by the tendons of this muscle, and of the extensor communis and proprius. The posterior is crossed by an oblique line (T, 1, Plate XXV.) descending from the fibular articular surface to the internal line, and forming two spaces, the superior of which, triangular, is covered by the poplitceus inserted into the oblique line, while the lower, occupied by the tibialis posticus and flexor longus, presents also the medul¬ lary holes. The tibia, compact in the diaphysis, with medullary canal, cancellated in the epiphyses, is ossified in three por¬ tions, one for the former part, and one for each of the latter. The fibula, which is the most slender bone of the skele- The leg- ton of equal length, is situate at the outer side of the hone. tibia, with its lower extremity anterior to the plane of the upper, articulated above with the latter bone only, below with the tibia and astragalus at once. The head or tibial end, which is of an irregular cuboi- dal shape, presents above an oblique, trilateral, cartilagi¬ nous surface, articulated with that behind the external tibial tuberosity, by which also it is overhung. Before is a triangular surface; slightly convex, for part of the femo- ro-tibial ligament; behind, a tubercular surface for liga¬ mentous insertions; and externally, between the two, is an extensive pentagonal surface lor the insertion of the 36 ANATOMY. Special bicipital tendon, terminating above in an angular point, to internal lateral sinuosity for the passage of the flexor Special Anatomy, which is fixed the peroneo-tibial ligament. tendons, that of the tibialis posticus, and the posterior Anatomy. The lower or tarsal end consists of a pointed trilateral tibial artery and nerves; and, lastly, an external lateral pyramid, the external surface of which, somewhat convex, surface, covered by integuments and the tendons of the is subcutaneous, and forms the external or fibular ankle lateral jjeroncci. (malleolus externus) (e). Within is a trapezoidal cartilagi- The scaphoid bone is connected by its posterior con- nous surface, which is articulated with the and cave surface with the anterior convex one of the astra- behind and below is a rough triangular surface, with a cavi- gains, and presents before a cartilaginous surface with ty for the insertion of the fibulo-tarsal ligament, while the three facettes for the three cuneiform bones, and on the external ligament is fixed to its angular tip. The poste- outside a small facette for the cuboid. On the inside is rior surface presents a groove, sometimes two, incrusted a prominent tuberosity for the attachment of the tibialis by fibro-cartilage for the motion of the peroncd longus posticus. The cuboid bone, which constitutes the outer et brevis. margin of the tarsus, and is articulated with the trilateral The body is marked by several lines inclosing sur- surface of the calcaneum, and by a minute facette with the faces rather irregular in shape and extent. Among the scaphoid bone, is chiefly distinguished by an oblique or former the following may be recognised:—An anterior, diagonal groove, for the tendon of the peronceus longus. commencing about 2^ inches below the head, distinct in The third and fourth metatarsal bones are articulated to the middle, where the aponeurosis common to the exlen- its anterior surface. sor longus digitorum and peronceus tertius before, and the The three cuneiform bones agree in having posterior car- peronceus longus et brevis behind, is attached, and bifur- tilaginous surfaces for articulation with the scaphoid eating about 2^ inches above the lower end into an ante- bone, and anterior ones for that with the first phalanx of rior and posterior, terminating on the anterior and posterior the great toe, and the metatarsal bones of the second and margins respectively of the malleolus externus, inclosing a third toes. The internal surface of the large cuneiform triangular space, which is covered by integuments only, bone is convex, covered by integuments; the external or The internal, descending from about an inch below the fibular cartilaginous, with two facettes for articulation with head to the anterior edge of the internal malleolus, coin- the second cuboid bone and the first metatarsal. Its cides there with the anterior part of the anterior line. To lower surface is irregular for the insertion of the tibialis this, above and in the middle, the tibialis posticus andflexor anticus, and part of the tibialis posticus. The second cunei- proprius pollicis, and below the interosseous ligament, are form bone, which is the smallest of the three, and the most attached. The external or posterior descends from the pos- like its name, is wedged between the scaphoid behind, the terior part of the head, obtuse, and winds round below to first and third on each side, and supports the first metatar- the posterior part of the tarsal end, giving attachment to sal bone before. The third, which also is not unlike its an aponeurosis intermediate between the lateral peroncei denomination, is wedged between the scaphoid behind, and without, and the flexor proprius and solceus behind. Be- the second cuneiform and the cuboid bone, and sustains tween the external and the anterior is an oblique line, to the second metatarsal bone; while the third and fourth which the interosseous ligament is fixed. are articulated with the anterior surface of the cuboid. The external surface between the anterior and posterior Of the metatarsal bones there are four; the first three The meta- ines, narrow above, convex and broad in the middle, and similar to each other; the fourth, which sustains the pha-tarsal binding spirally round the axis of the bone, is covered by langes of the small toe, distinguished by a large oblique b01168, the peronceus longus and brevis. An anterior, plane, is angular head for the insertion of the tendon of the pe- covered by the extensor longus and peronceus tertius. The rorueus brevis, while that of the peronceus tertius is fixed internal or tibial is divided by the oblique line into two; above. Of the other three the heads are trilateral or an anterior for the extensor proprius, and a posterior for wedge-shaped with the base upwards, with cartilaginous the tibialis posticus. To the posterior surface above, which facettes on the sides for mutual articulation. The bodies is convex, the solceus is attached; and in the middle and are cylindrical, and, tapering, terminate in round heads below the flexor longus pollicis ; while, by the rough trian- flattened laterally. The dorsal or upper surface is covered gular surface below, the bone is articulated with the tri- by the extensor tendons, the extensor brevis digitorum, and lateral cavity of the tibia. the dorsal vessels and nerves derived from the anterior tibial Theflbula, which is ossified in three portions, partakes artery and nerve. The surface of these bones is so con- of the general characters of structure common to the long structed that it forms an arched or convex inclined plane, bones. descending from the tibial to the fibular side of the foot. The tarsus. The tarsus consists of seven short irregular-shaped In the anterior or plantar surface, which is concave, are bones, the astragalus, the heel-bone (calcaneum, os colds'), lodged the abductor hallucis, abductor minimi digiti, flexor the scaphoid, cuboid, and three cuneiform bones. brevis, the flexor tendons, the accessory flexor, the lumbri- The first (talus, astragalus) has a convex cartilaginous cales pedis, flexor brevis hallucis, abductor hallucis, flexor surface above for articulation with the lower end of the brevis minimi digiti, transversalis, and the external and tibia, continuous with a similar trilateral concave surface internal ranges of the interossei. on the inside for articulating with the malleolar process, The phalanges of the toes, in number 15, bear a gene-The pha- and with a smaller triarcual surface on the outside for the ral resemblance to those of the fingers; but are consider-langes. fibula; two cartilaginous surfaces, separated by a deep ably shorter, unless in the instance of the great toe. Like pit below, for articulating with the calcaneum; and an these also, they are disposed in three ranges,—metatarsal, anterior eminence, with a convex cartilaginous surface, for middle, and unguinal. articulating with the scaphoid bone before. The calca- The bones now described are united so as to admit ofThe pelvic neum, which is the largest, consists of the posterior tube- different degrees and forms of motion. The head of the e.xtr.emi- rosity (talus) (c), for the insertion of the united tendons of femur, lodged in the acetabulum, is retained in that cavity the gastrocnemius and solceus, and that of the plantaris; not only by the capsular and round ligaments, but by The hip- two upper cartilaginous surfaces, separated by a ligament- the numerous strong muscles with which the hip-joint j0int. ous pit, for articulating with the astragalus ; an anterior is surrounded. The length of the neck, which is peculiar cartilaginous trilateral surface for the cuboid bone; an to the human subject, throws the supporting column of ANATOMY. 37 Special the bone to a greater distance, not only from the pelvis, Anatomy, but from the mesial plane and centre of gravity; and this character, with the great proportional length of the bone, and the extent and direction of the pelvis, constitutes the most decisive argument in favour of the doctrine, that man must support himself in the erect position on the two pel¬ vic extremities. In most quadrupeds the neck of the femur is short; the cylinder is shorter than the tibia, and not arched ; and the pelvis, both by its vertical direction and peculiar dimensions, is calculated for the quadruped motion only. The femur admits of motion in every direc¬ tion,—flexion, extension, adduction, abduction, circum¬ duction, and rotation. The knee- The tibia, with its appendage the knee-pan, is articu- joint. lated to the condyles of the femur by means of an exter¬ nal and internal lateral ligament, strengthened by an an¬ terior or patellar ligament, posterior fibres, and an anterior and posterior cross ligament, contained within the synovial membrane. The effect of this arrangement, with the ana¬ tomical configuration of the articular ends, is to allow car¬ dinal opposition, or flexion and extension only. A small degree of rotation, nevertheless, may be effected. The fibula, is articulated to the tibia above by a genu¬ ine capsular joint, and below by fibrous matter, and con¬ nected at its internal side by a duplicature of periosteum forming the interosseous ligament. These connections ad¬ mit of little motion, and the chief use of the fibula is to give attachment to several muscles which bend or evert the foot. The chief weight of the person, divided as it is between each lower extremity, is communicated from The ankle-the pelvis to the femur, thence to the tibia, and finally to joint. the astragalus and calcaneum behind, and the metatarsal bones before. The motion of opposition is confined to the former, which rolls backwards and forwards in the ca¬ vity formed by the lower extremity of the tibia and the fibula in the flexion and extension of the foot. In this, therefore, which forms the ankle-joint, all the motions of the foot as a whole are executed. It appears further to be susceptible of a slight degree of lateral rotation, so as to contribute to the eversion and inversion of the foot. The tarsal bones are mutually connected by cartilagi¬ nous surfaces, and secured by numerous fibrous bands, so as to admit of the gliding motion only. This motion is further between each individual articulation very limited, and its general amount is inconsiderable. The great use of the tarsal articulations is evidently stability and solidity as a base of support, not mobility. The arches The bones of the foot form two distinct and separate ot the foot. arc]leg5—an antero-posterior and a transverse. The first is constituted by the posterior part of the heel-bone be¬ hind and the metatarso-phalangeal articulations before; and its chief use is to distribute the weight of the extre¬ mity from the astragalus, which may be regarded as the centre, to the os calcis and extremities of the metatarsal bones on each side. In standing, for example, either on one foot or both, the weight of each extremity is distri¬ buted before to the metatarso-phalangeal joints, and be¬ hind to the tuberosity of the os calcis, while the anterior part of the latter bone and the whole second range of tar¬ sal bones do not touch the ground. The second arch re¬ sults first from the arrangement of the cuneiform bones with the scaphoid, and that of the cuboid with the os calcis; and next from the arrangement of the metatarsal bones. These arches, which are indistinct in early life, become conspicuous as the bones are completed, and acquire their complete developement in adult age. These arches are of great use in the alternate elevation of each half of the person in progression, in ascending an inclined plane or a series of steps, and especially in springing and leaping. The phalanges are articulated with the metatarsal bones Special and with each other, so as to admit of flexion and exten- Anatomy, sion chiefly, with a very limited extent of abduction and^'^'^^^ adduction. The articulation of the great toe, also des¬ titute of the power of opposition, abridges much its ex¬ tent of motion. While these circumstances, with the great brevity of the phalanges, render the foot much less perfect than the hand as an organ of prehension, they extend its sphere of support, and enlarge its powers as a locomotive agent. The pelvic and thoracic extremities present several Parallel points of resemblance which have been well traced bybetween Soemmering. The head, neck, and tuberosities of the ^ thora* humerus resemble the head, neck, and trochanters of tile C1.C an(l pel- femur; and if the lower end of the former bone is arti- mities re* culated both with the ulna and radius, while that of the latter is connected to the tibia only, there is still sufficient analogy between the lower ends of both bones. The tibia resembles the ulna above, with the knee-pan corre¬ sponding to the olecranon ; but the lower extremity of the tibia is represented by that of the radius, in consequence of the extensive connection of the latter bone with the carpus for the purpose of pronation and supination. The navicular and lunar bones of the carpus are represented by the single astragalus,—an arrangement which appears to be allied in the latter case to the purpose of stability and solidity. The calcaneum may be regarded as an en¬ larged os magnum, fitted for the same purpose ; and even in the shape and position of the scaphoid bone the same object may be recognised. This comparison, however, it is superfluous to pursue farther. The general conclusion is, that the thoracic extremities are intended to combine with strength great extent and precision of motion, while the purpose of the pelvic is stability, solidity, and strength. SECT. II. MYOLOGY ; THE ANATOMY OF THE MUSCLES. The muscles, with their appendages the fasciae, tendons, The mua- and synovial sheaths, constitute the second division of the ck‘s- locomotive organs. By the term muscle, indeed, in Spe¬ cial Anatomy, is meant not only a mass of flesh adequate to effect motion, but an organ consisting of fascia, muscu¬ lar flesh, and tendon, connected by the first and last sub¬ stances to the parts, fixed or movable, to be approximated. While the middle portion is denominated belly (venter), the two extremities are most properly named attachments ; though by others they have been termed respectively head or origin (caput, origo), and insertion (insitio) or termi¬ nation (finis), according as the one or the other end has been imagined to be most fixed. By the contraction of the middle portion or belly the two extremities are approximated; and according as the one is connected with a bone or soft part more movable than the other, that movable portion is approximated to the fixed. This, which is the general effect of muscular action, is well exemplified in the primary bones of the extremities, the muscles of which have their fixed end in general in the trunk, and their movable end attached to the bones of the extremities. Thus in the case of thepecto- ralis major (p), Plate XXVIL, and latissimus dorsi (l, l), Plate XXVIII., the fixed ends are in the trunk, and the movable or insertions are in the humerus; and the effect of the contraction of the belly is to carry the humerus for¬ ward over the chest in the one case, and backward on the trunk in the other. This is easily applied to other muscles, as to those of the face. The converse of this arrangement nevertheless m ay take place. The extremity, which in ordinary circum¬ stances is the most movable, may be converted into the 38 ANATOMY. Special fixed; while that which is fixed becomes movable. Thus, Anatomy. jn the case 0f the two muscles already mentioned, the humerus may become the fixed point; and the effect will be to elevate and approximate the trunk to the part to muse es. ^ extremity is fixed. Though all the muscles are agents of motion, all are not of locomotion; and it is chiefly the muscles connected by both ends with the skeleton, and especially those of the extremities, which are entitled to this distinction. The muscles of the face are connected always by one end, often by both, with the skin, and hence are cutaneous muscles. Those of the lower jaw and pharynx are organs of motion simply to move the parts with which they are connected in the acts of mastication and deglutition. Those of the larynx are of two orders, the common or ex¬ trinsic, connected to some of the bones of the head and chest; and the proper or intrinsic, pertaining to the laryn¬ geal cartilages only. Those of the eye and ear, external and internal, are equally unconnected with the locomotive faculty. These circumstances have induced several authors, especially the ancient anatomists, and among the moderns Winslow, to arrange the muscles according to the parts which they move. By others, however, especially Dou¬ glas and Albinus, they have been classified according to the regions which they occupy; and this method, which is certainly more strictly anatomical, has been more or less adopted by Innes, Sabatier, Bichat, and Boyer. To the first method the principal objection is, that the same muscle may pertain to different classes of organs, and may effect different purposes in each; while of the se¬ cond it must be admitted, that it communicates no in¬ formation regarding the remarkable part which the muscles perform in the complicated processes of the animal ma¬ chine. This consideration it was which induced Albi¬ nus, after a minute description of the situation, connec¬ tions, and separate actions of each muscle of the human body, to construct a table representing the various classes into which they may be divided, according to the parts on which they act; for the same reason, doubtless, Soem¬ mering arranged them according to the organs to which they belong; and for the same reason Portal, after a de¬ scription equally minute with that of Albinus, gives a se¬ cond account of the muscles as they are observed to act in the living body. In the following tabular view, modified from that given by Albinus in the fourth book of his Historia Musculorum, the muscles are arranged according to their regions. Muscles of the Head, Neck, and Vertebral Column. Latissimus colli. (II.) Sterno-mastoideus. (th Order. Latissimus dorsi. (l.) Pectoralis major, (p.) Pectoralis minor, (p.) Muscles of the Arm. Coraco-brachialis. Triceps brachii. (Tr.) Biceps brachii. (b. b.) Anconeus. Brachialis internus. (Br.) Muscles of the Fore-Arm and Wrist. Supinator longus. (s.) Ulnaris internus. Radialis externus longior. Radialis internus. (f.) Pronator teres. (Pr.) brevior. Pronator quadratus. Ulnaris externus. Supinator brevis. Muscles of the Hand and Fingers. Extensor communis. Abductor brevis pollicis. Extensor proprius auricularis.Opponens pollicis. Abductor longus pollicis. Flexor brevis pollicis. Extensor minor pollicis. Extensor major pollicis Indicator. Palmaris longus. (p.) Sublimis. (f. s.) Profundus, (f.) Flexor longus pollicis. Extensor brevis indicis. Liimhrirales. Adductor pollicis. Palmaris brevis. Abductor digiti minimi. Flexor parvus digiti minimi. Adductor ossis metacarpi digiti minimi. Interossei interni. Interossei externi. AhdncT.nr indicis. Muscles of the Pelvic Extremities. The Hip. Glutaeus magnus. (gl.) Glutaeus medius. (g. i.) Glutseus minor. Pyriformis. Gemini, (g. g.) Obturator internus. (ob.) Obturator externus. Quadratus femoris. (q.) Psoas magnus. Iliacus internus. Muscles of the Thigh. Biceps cruris, (b.) Vastus externus. (v.) Semitendinosus. (s. t.) Vastus internus. {y.) Semimembranosus, (s. m.) Cruralis. Tensor vaginae femoris. (t.) Pectinaeus. Sartorius. (s.) Adductor longus. a. Gracilis, (g.) Adductor brevis. Rectus. Adductor magnus. a. Special Anatomy. The muscles. ANATOMY. 39 Muscles of the Leg and Tarsus. Special Gemellus. The Plantaris. muscles. Solauis. Poplitaeus. Flexor longus digitorum pedis. Flexor longus hallucis. Tibialis posticus. Peronaeus longus. (p.) Its ten¬ don in the groove of the cuboid bone. Peronaeus brevis. Extensor 1. digitorum pedis. Peronaeus tertius. Tibialis anticus. Extensor proprius hallucis. Muscles of the Foot and Toes. Extensor brevis digitorum Abductor digiti minimi pedis. pedis. Flexor brevis digiti minimi Flexor brevis digitorum pedis, (f.) pedis. Transversus pedis, (tr.) Abductor hallucis. Lumbricales pedis. Flexor brevis hallucis. (f. 4.) Interossei interni pedis. Adductor hallucis. (a. d.) Interossei extern! pedis. Muscles of the Lower Jaw. Biventer maxillae. Pterygoideus externus. Masseter. Pterygoideus internus. Temporalis. Proper Muscles of the Eye. Attollens. (a.) Plate Adductor. Ad. XXXIII. fig. 6. Obliquus superior. Tr. Depressor, (d.) Obliquus inferior. Abductor. (Ab.) Proper Muscles of the Ear. Laxator tympani major. Tensor tympani. Laxator tympani minor. Stapedius. Muscles of the Anus and Perinceum. Transversus perinaei. Levator ani. Transversus perinaei alter. Coccygeus. Sphincter ani externus. Cm /ator coccygis. Sphincter ani internus. Muscles proper to the Male Generative Organs. Cremaster. Bulbo-cavernosus. Ischio-cavernosus. Compressor prostatae. Muscles proper to the Female Generative Organs. Ischio-clitoridaeus. Depressor urethrae. Constrictor vulvae. Special Anatomy. '^The^ muscles. Muscles common to the Hyoid Bone, Tongue, and Larynx. Omohyoideus. Styloglossus. Stcrnohyoideus. Mylohyoideus. Sternothyroideus. Geniohyoideus. Hyothyroideus. Hyoglossus. Thyroideus. Genioglossus. Stylohyoideus. Lingualis. Muscles of the Palate and Pharynx. Levator palati. Palato-pharyngeus. Azygos uvulae. Stylo-pharyngeus. Circumflexus palati. Salpingo-pharyngeus. Constrictor isthmi faucium. Constrictores pharyngis. Proper Muscles of the Larynx. Crico-thyroideus. Arytaenoideus transversus. Crico-arytaenoideus posticus. Thyro-arytaenoidei. Crico-arytaenoideus lateralis. Thyro-epiglottici. Arytaenoideus obliquus. Muscle of the Scalp. Epicranius. (e, bE, bE, e.) Muscles common to the Face and Eye. Orbicularis palpebrarum, (o.o.) Levatorpalpebrae superior is. Corrugator supercilii. Muscles Compressor narium. (c.) Levator labii superioris alae- que nasi, (l.) Muscles Levator labii superioris. Zygomaticus minor, (z.) Zygomaticus major. (Z.) Levator anguli oris. Depressor anguli oris. Muscles common Attollens auriculam. Prior auriculae. Retrahens auriculam. Major helicis. of the Nose. Nasalis labii superioris. (N.) Depressor alae nasi, (d.) of the Lips. Depressor labii inferioris. Buccinator, (t.) Orbicularis oris. (o. o.) Anomalus maxillae superioris. Levator menti. 9 the Ear and Scalp. Minor helicis. Tragicus. Antitragicus. Transversus auriculae. The limits assigned to the present treatise preclude particular details on the situation and relations of this nu¬ merous list of muscular organs. Any description suffi¬ ciently minute for the purpose of explaining the situa¬ tion, attachments, relations, and actions of the muscles of the different regions, would be tedious in the ex¬ treme, and would not be intelligible without dissection; and no description according to their actions only would be intelligible, without a previous account of their anato¬ mical relations. For these reasons it seems most expe¬ dient to direct the attention of the reader to a few gene¬ ral circumstances only. For descriptive details the reader will study with advantage the third book of the elaborate and accurate Historia Musculorum of Albinus, or the more recent treatise of Sandifort. The descriptions of Innes are clear, short, and sufficiently minute ; and a good account of the muscles, as they appear on exposition, is given in the London Dissector. Of systematic treatises, the second volumes of those of Soemmering, Portal, and Bichat are the best. This section, therefore, we shall conclude with such a general view of the muscles as agents in the attitudes and motions of the trunk and extremities, as, with the occasional remarks on their situation and connections in describing the bones, may be easily intelligible. It is further proper to advert briefly to those of the flexor muscles of the fingers, partly with the view of illustrating the general effects of muscular action, partly to show the mechanism by which the hand and fingers are en¬ abled to execute such a variety of nice and delicate motions. The muscles of the trunk are employed not only as Muscles of agents of motion and sustentation, but as the protecting the trunk, walls of the large cavities. Thus the external and inter¬ nal ranges of intercostals, the two pectorals, and the ser- ratus magnus, operate not only in moving the ribs and shoulder respectively, but in contributing to complete the walls of the thorax, and to protect the internal organs. The diaphragm is not only an agent in enlarging the chest downwards, but constitutes an essential partition between the thoracic and abdominal viscera, prevents the lungs and heart from descending into the abdomen, and the stomach and bowels from being thrust upwards into the chest. These characters are still more conspicuously displayed in the recti abdominis, obliqui externi et interni, and tram- 40 ANATOMY. Special versi abdominis, which operate a little in drawing the chest Anatomy^ downwards and compressing it before and on the sides, but The aCt muc^ morf powerfully as retaining and supporting walls muscles. abdominal viscera, counteracting by the inward and upward action the downward impulse of the diaphragm. In this manner the abdominal viscera, placed between two opposing but equally balanced powers, are retained in the cavity, and prevented from being protruded upwards or downwards, while they are subjected to the alternate mo¬ tions of inspiration and expiration. The muscles of the trunk are employed in retaining that part of the skeleton in the erect attitude, in balancing it properly on the pelvic extremities, in occasionally inflect¬ ing and extending it, in bending it to one side, or in pro¬ ducing rotation. Those of the spine and back are parti¬ cularly the agents of the erect attitude, and of extension ; and those of the anterior region are employed in inflect¬ ing the person. Muscles of The muscles of the superior extremities taken together the thora- are the agents of numerous varied motions. Though the uuties^" Pr*ncTal object of the thoracic extremities is prehension, or embracing any object or objects firmly either by one or both hands, this may be modified in various ways, so as to give rise to prepulsion, traction, and constriction; while diduction and circumduction are the result of the combinations of the simple movements,—abduction, ad¬ duction, flexion, and extension. Prepul- Prepulsion may be either instantaneous or continued. Sion. The first takes place in the act of inflicting a blow or re¬ pelling an object. All the flexors are previously put in action to shorten the member, which is then at once for¬ cibly extended, and communicates a violent shock to the part of the object to which its extremity is applied. Of this motion, in which the extension takes place in the scapulo-humeral and humero-cubital articulations, the deltoid and brachialis externus, or third head of the triceps, are the chief agents. The wrist and fingers are almost passive. But an analogous motion is exe¬ cuted by the latter in giving a fillip. In continuous prepulsion, for instance, or the act of impelling an object, the mechanism is of two kinds. In the first case, the member being previously extended and supported on the object, the individual inclines the trunk, and avails himself of its weight; while the member, remaining pas¬ sive, becomes a lever moved by gravity. In the second case, the continued action of the extensors retaining the member forcibly extended, impels the object without in¬ terruption. When, for example, a man pushes a wheel- carriage before him, the superior extremities are extend¬ ed and communicate motion to the carriage, while the trunk approaching it immediately, the extremities are again inflected, and so forth successively. In most in¬ stances this twofold mechanism is combined. When in prepulsion the body impelled is fixed, the impulse is thrown back on the person of the prepelling agent. Ex¬ amples of this effect of prepulsion are observed in the act of rising from a seat by the occasional use of the thoracic extremities, and in pushing a vessel from the shore by means of an oar or pole. Traction. Traction, which consists in a general action of the flexors of the thoracic extremities, is directly the reverse of prepulsion. Its effect is to diminish the space between the agent and the object drawn, which takes place by shortening the member; while in prepulsion this space is enlarged by elongating or extending the member. In the case of a very great effort, for instance that of detach¬ ing a piece of wood strongly fixed in a wall, the action of the flexors is aided by the weight of the trunk, which is instinctively inclined in the opposite direction ; and if the body drawn yields at once, a fall is often the result, be- Special cause in this inclination the centre of gravity is subverted. Anatomy. In another form of traction, in which the body grasped does not yield, and when the action takes place upwards, the effect is to elevate the person of the agent by the flexors of the superior, and even occasionally of the inferior extremities. Familiar examples of this are afforded in the act of climbing walls, trees, and occasionally rocks, in as¬ cending the rigging of a ship, and still more forcibly in the manner in which the active seaman ascends a single rope. Constriction consists in the forcible and continued in-Constric- flection either of a single hand or of the whole of bothtion. members. In the first case the agents are the superficial and deep flexors, and the flexors of the thumb and little finger; and in the second, with the action of these muscles, that of the biceps, brachialis internus, and coraco-brachialis is combined. This motion can neither be so sudden as that of prepulsion, nor, like it, can it be aided by the weight of the person. Diduction, which consists in the forcible separation of Diduction. the upper extremities from each other, as in swimming, is effected partly by the latissimus dorsi and teres major, partly by the posterior fasciculi of the deltoid moving the whole extremity in the scapulo-humeral articulation. Circumduction, which also is exclusively confined toCircum. the scapulo-humeral articulation, is effected principally duction. by the deltoid, large pectoral, latissimus dorsi, teres major, &c.; while rotation is performed by the supraspinatus, infraspinatus, teres minor, subscapular is, &c. Besides these general classes of motion executed by Gesture, the thoracic extremities, to them also belongs the power of assuming many of those attitudes and all the varieties of gesture which man employs for the purpose either of expressing his feelings or giving significance and ani¬ mation to the language which he adopts for that purpose. How much these gestures, when well chosen and properly introduced, aid both the expression of the countenance and the language of the lips, is w^ell known to the public speaker and the dramatic performer. Besides the ordinary flexors of the wrist (radialis ra-Motions of ternus et internus, ulnaris internus), there are two common band and flexors of the fingers, one superficial {sublimis), the other ^nger& deep-seated (profundus); the thumb has a long and short flexor, and the little finger has a short flexor. The flexor muscles, therefore, may be distinguished into four orders ; those common to the wrist and hand, those common to the hand and fingers, those proper to the fingers, and those proper only to some of the fingers. Though the radialis internus and ulnaris internus chiefly bend the wrist and hand, yet both the superficial and deep flexors, by passing beneath the annular ligament, co-operate in the same motion, and necessarily bend the hand previous to their final action on the digital phalanges. In this they are considerably aided by the action of the palmaris lon- gus and the palmaris brevis, which render the palmar apo¬ neurosis tense, and enable it to afford the necessary resist¬ ance to the subjacent flexor tendons. The superficial flexor, the tendons of which are insert¬ ed into the anterior and citerior part of the second row of phalanges, has the effect of bending that part of the fingers; and further, by being bound down by a ligamentous sheath to the first phalanx, inflects them at the same time into the palm. The slits in each tendon allow those of the deep flexor to pass forward on the median line of each phalanx, to be inserted in the unguinal phalanges, and thereby to operate most directly and perfectly in inflecting them on the palm ; and, by being confined also in the same sheath by strong ligamentous bands, aid in inflecting the second and first range of phalanges. (Plate XXVIII. fig. 2 and 3.) ANATOMY. 41 and fin¬ gers. Special These actions are further facilitated and modified by Anatomy, another class of muscles. The lumbricales, which, situate in the palm, are attached above to the tendons of the flexor Minute ■profundus, and inserted sometimes into the extensor ten- exteivion^ ^ons’ sometimes into the lateral regions of the phalanges, cx ension. ejther concur with the profundus in bending the first phalanges, or they may adduct or abduct the fingers, ac¬ cording to the separate or conjunct motion ; and hence are of the utmost importance in all nice and minute motions of the fingers. Without the lumbricales, which are peculiar to man, it would be impossible for the human fingers to execute those minute and rapid movements which are necessary in performing on musical instruments; and the great advantage which one individual possesses over an¬ other in what is denominated execution, consists chiefly in the perfect use of these little muscles. In playing on the piano-forte especially, the lumbricales are of the most es¬ sential service; and though the superficial flexor enables a lady to strike the keys, the former must be employed in the more minute and delicate motions requisite in the transition through numerous chords. In this action the internodii at the same time appear to be auxiliary; and their connections are calculated to mo¬ dify the action of the flexors. Opposition Another peculiarity in the human hand consists in the of thumb four muscles with which the thumb is provided, and the two connected with the little finger. By means of its short abductor, short flexor, and adductor, the thumb may be separated, inflected, and approximated to the hand quite independently of the fingers, and with the utmost precision. But from the opponens it derives the remark¬ able property of being accurately and precisely applied to the tip of any one of the fingers, and thus made to grasp minute objects, which could not Avithout this be effected. From this muscle, in short, the human hand derives its power of appliance to all the arts requiring nice manual operation. Without the opponens there is no penmanship, no painting, no drawing, no tracing, no needlework, no engraving ; in short, none of those operations requiring the obedience of the hand to the conceptions of the mind and the guidance of the eye. The movements of the lower extremities are less dis¬ tinguished for precision and delicacy than those of the . superior; and though the foot has both lumbricales and inter- extremi-C osse^ ^le brevity of the phalanges compared with the length of the metatarsal bones, and the close connection of the toes, form insurmountable impediments to the rapidity and nicety of motion which is observed in the inflections of the fingers. The circumstance, however, which places the foot at an immeasurable distance behind the hand as an organ of prehension, is the Avant of the opponens. Void of this, the human foot is little more than the foot of the quad¬ ruped, constituting chiefly a base of support, and suscep¬ tible of such motions only as are requisite to progression. It is expedient, therefore, to consider shortly the agents by which these functions are performed. Station, or that attitude in which man supports himself both legs, in the erect position on a horizontal plane, is effected by the foot being planted firmly on the ground by means of the gemellus, solceus, tibialis anticus, peronceus longus et brevis, flexor longus communis digitorum pedis, flexor hallucis proprius, flexor hallucis brevis, flexor brevis digiti minimi et digiti medii, the lumbricales, and interossei. At the same time the leg is fixed to the ground by numerous muscles,—before by the extensors of the great toe and toes generally, by the peronceus tertius, partly by the tibialis anticus ; externally by the peroncei longus et brevis ; Avithin by the tibialis anticus and posticus; and behind by the gemellus, solceus, semitendinosus, and long flexors of VOL. in. General move¬ ments of extremi ties. Station on the toes. The knee is at the same time stretched by the Special four extensors, aided by the tensor vagince femoris. Anatomy. The equilibrium of the trunk and pelvis on the heads of the thigh-bones is maintained by several powerful mus-^11'!10'^* cles, connecting the former to the latter. Before, for in¬ stance, this action is performed by the sartorius, rectus, the two psoce, and the iliacus internus ; behind by the biceps, semitendinosus, and semimembranosus ; without by the glu- tceus and tensor vagince femoris; and within by the pec- tinceus, the adductors, and the gracilis. By these muscles the pelvis is impelled on the axis of the two femora only, and is prevented from inclining in any other direction. To maintain the trunk above the pelvis in the same steady position, numerous other muscles concur. Behind are the various extensors of the vertebral column and trunk ; the longissimus dorsi and sacro-lumbalis on each side, the cervicis descendens, splenius and biventer cervicis ; the trans- versi cervicis, and spinalis cervicis et dorsi ; the semispinalis, multifidus, and interspinales on each side. Before are the sterno-mastoid, the great and small anterior recti, the longi colli, and anterior scaleni; and on each side are the trachelo-mastoid, the lateral scaleni, the intertransversi, and the lateral recti. In this enumeration it is manifest that the muscles of the posterior surface of the trunk and spine are at once more numerous and more powerful than those on the anterior,—an arrangement which is rendered necessary to counteract the effect of the weight of the thoracic and abdominal viscera on the anterior side of the vertebral column, which is thus rendered liable to anterior incurvation, and which becomes so in old age, notwithstanding the agents now mentioned. This circumstance is further illustrated in the number and size of the muscles by which the head is retained in the erect position, and prevented from inclining forwards. These are the cucullares, the splenii capitis, biventres cer¬ vicis, and posterior recti on each side—all powerful, and several of them large. Station on both pelvic extremities, therefore, requires the co-operation of a very considerable number of power¬ ful muscles ; and it is a mistake to imagine, as some authors appear to do, that a small degree of muscular energy is requisite for this purpose, and that the skeleton is the chief means of maintaining the erect position. Without the skeleton, as points of support, the muscles cannot act; but without the muscles the bones are passive brute matter. In station on one extremity only, a different and cer-Station on tainly a less degree of muscular action is requisite. Allone lefer- the external muscles of the fixed member are at first strongly contracted, to prevent it from gliding inwards, in which direction the trunk, not supported by the opposite limb, tends to impel it. Proceeding from below upwards, we find the lateral peroncei, the vastus externus, and even the rectus, draw the limb outwards ; Avhile the tensor vagince femoris, the glutceus medius and minor, carry the pelvis, and with it the trunk, in the same lateral direction. In this case the weight of the person is employed in an¬ tagonizing the muscles of the side throAvn into action; and the person is balanced between these two forces. Elevation on the tip of the foot is effected chiefly by the action of the muscles, which extend the phalanges on the metatarsal bones, viz. the tibialis anticus, extensor hal¬ lucis, extensor longus digitorum, and even the extensor brevis ; all of which must fix the leg before, and the tarsal and metatarsal part of the foot on its phalangeal region, before the latter can be employed to elevate the person. These extensors, therefore, perform in the tip-toe atti¬ tude the duty which the gastrocnemius and solceus exe¬ cute behind in ordinary station; and the smaller power # 42 ANATOMY. Special of the former readily explains the difficulty of maintaining Anatomy, attitude for a long time. Progression or gait (incessus) consists in the anterior sion^68" propulsion of the person by the alternate propulsion of each pelvic extremity. In this, therefore, not only are the muscles necessary to maintain the erect position put in action, but those which bend the lower extremity on the trunk operate on one side, while the extensors of the other maintain that extremity for the instant fixed. Pro¬ gression consists of a series of steps (passus); and each step consists in the antero-posterior separation of the pel¬ vic extremities by the propulsion of one, while the other remains fixed. Supposing the left foot to be the fixed one, the right foot is elevated, and the leg is propelled by the contraction of the gemellus, solceus, semitendinosus, tibialis anticus et posticus ; while at the same time the ex¬ tensors of the knee raise the leg, and the psoas, iliacus, pectinceus, triceps adductor, sartorius and gracilis, with the tensor vaginae femoris, raise and stretch the whole limb. When this is accomplished, the right foot, with the knee extended, the elevating muscles being relaxed, and the trunk, are inclined forwards, and the foot is planted at some distance before the left. In this motion, however, in which the trunk is carried forward by the recti and obliqui abdominis, and downward by the psoae and iliaci interni, and the leg by the long flexor and the anterior peronceus, a fall would be the im¬ mediate result, unless the knee, to preserve equilibrium, were somewhat bent, and the other foot at the same time began to assume the same action. While the toes, there¬ fore, are forcibly impelled by their flexors to the ground, the two gastrocnemii, the anterior and posterior tibiales, and the peroncei, elevate the foot with the sole backward, and bend the knee, and the psoas and iliacus raise and extend the whole member. Running. Running differs from progression, not only in velocity, but in the mode of its accomplishment. Not only are the pelvic extremities more inflected and moved than in mere walking, but they remain inflected. Thus, while the trunk is inclined forward on the pelvic extremities by the recti cruris, the psoae and iliaci, the two latter with the pectinceus longus, the adductor longus and brevis, and the tensor, are employed to inflect the thigh, the semi¬ tendinosus, semimembranosus, and biceps to inflect the leg, and the anterior tibialis, great and small extensors of the toes, and extensor of the great toe, are employed to bend the foot and the phalanges on the metatarsal bones. The last action is essential to running, which is always most perfect on the tip of the foot. In this movement also the centre of gravity is constantly undergoing change, and is not only carried forward, but makes a sort of undulating motion on each side, and above and below the plane of motion. This is the effect of the pectoral extremities being employed to balance the person. Leaping. In leaping, the pelvic extremities are much inflected, and the sole of the foot rendered tense, by the gastrocne¬ mius, solceus, tibiales, and. peroncei, while the extensors are employed to raise the phalangeal part of the foot; when the person is forcibly impelled forward by the gastrocne¬ mius, solaeus, the leg suddenly contracting on the crurceus in the thigh, and the glutceus, semitendinosus, semimem¬ branosus, and biceps in the pelvis. Dancing. In dancing, the muscles are made to co-operate in pro¬ ducing a number of complicated motions. In most of the motions composing the dances practised in ordinary socie¬ ty, while the muscles of the pectoral extremities are em¬ ployed in balancing the person, and those of the trunk in maintaining it in the erect attitude, the flexors and ex¬ tensors are employed to diduct, inflect, or extend; to cross the extremities with more or less rapidity ; and, Special while the extensors and tibialis anticus elevate the person Anatomy, on tip-toe, the lateral peroncei are employed to evert the foot and point the toes. CHAP. II.—THE ORGANS OF SENSATION. The organs of sensation may be distinguished into two orders, according as their province is to recognise general or peculiar affections and qualities in external objects. Thus, while it is the purpose of touch to recognise the consis¬ tency, shape, and resistance of bodies, it communicates no information regarding their colour, smell, or taste, or the effects which their collision produces in the vibra¬ tions of the atmosphere. With these affections of the ma¬ terial world man becomes acquainted by means of organs of a peculiar construction, and adapted to receive the impressions occasioned by these qualities. These organs are, for smell, the nostrils and their appendages; for colour and the general purposes of sight, the eye; for taste, the palate and mouth; and for sound, the ear. For the pur¬ poses of common sensation the skin is the agent; but on the structure of this membrane it is unnecessary to add any thing to what has been already said in the General Ana¬ tomy, unless that in certain regions, for instance the tips of the fingers, the erectile arrangement of the capillaries, with a minute distribution of nerves, and great thinness of cuticle, communicates the delicacy necessary to the re¬ fined purposes of tact. SECT. I. THE ORGAN OF SMELL ; THE NASAL CAVITIES. The organ of smell consists of an external part for re¬ ceiving and transmitting substances capable ot producing the sensation of smell; and an internal part, in which this sensation takes place. The nose (nasus), which constitutes the external part, The nose, is a pyramidal eminence, bounded above by the forehead, below by the upper lip, and on the sides by the orbits and cheeks. It has two anterior-inferior oval-shaped lateral openings named the nostrils (nares), separated by a par¬ tition. ^ It consists above of the nasal bones and the nasal processes of the superior maxillary bones, covered by periosteum, cellular tissue, part of the compressor narium, and skin. Below, it consists of membranous fibro-carti- lages, attached to the nasal bone and superior maxillary above and behind, and supported by a middle cartilage {septum narium), which rests on the fissure of the vomer below, and is fixed to the vertical plate of the ethmoid bone above, and to which is attached a slip of fibro- cartilage before, named columna nasi. The lateral fibro- cartilages, which are occasionally named wings {alee nasi, pinnae nasi), covered by cellular tissue, muscles, and skin, liberally supplied by blood-vessels and sebaceous follicles, are moved by the levator, compressor, and two de¬ pressors. These parts, with the middle septum and co¬ lumna, are lined by a form of mucous membrane named the pituitary or Schneiderian. To what was already said of the nasal cavities under the head of Osteology it is superfluous to add any thing, unless what relates to the lining membrane, the distribu¬ tion of which is exactly according to the extent of the bony walls of these cavities and their subdivisions. This membrane consists of two layers; a fibrous, which is Narine the periosteum or perichondrium of the nasal cavities; and membrane, a mucous, resembling the other forms of this tissue. It is soft, spongy, red, and more or less vascular, with an at¬ tached and a free surface, the latter secreting the thin mucus necessary to preserve the membrane in a proper state for receiving odorous impressions. In this mem- * ANATOMY. 43 Special brane mucous glands are indistinct; but we recognise mi- Anatonw. nute orifices or pores, which may be the follicular cavities on a small scale, or the orifices into which the mucous fluid is poured after secretion by the arteries. This mucous membrane is supplied from the internal maxillary artery with blood-vessels, which are at once abundant and superficial. These anastomose with the in¬ fra-orbital and ethmoidal branches of the ophthalmic ar¬ tery and some others of the internal carotid. On these circumstances depends the frequency of hemorrhages from this membrane in early life, while the capillary sys¬ tem is energetically employed in the enlargement of the cranio-facial region; and in advanced life, when venous plethora is most conspicuously evident in the vessels of the head. The nerves which supply the nasal cavities are the first or olfacient nerves principally, the internal nasal of the ophthalmic, and several branches derived from the spheno¬ palatine ganglion, the frontal, the great palatine, and the vidian. The distribution of these nerves has been beau¬ tifully represented by Scarpa (Annot. Acad.), from whom fig. 1 and 2 of Plate XXXIII. are imitated. SECT. II. THE ORGAN OF VISION ; THE EYES. The eyes, placed in the orbits, are distinguished into the globes of the eyes, and their appendages. The globe or ball of the eye, situate at the base of the orbit, has a spheroidal shape, with the antero-posterior diameter longest, and varying in the adult from 10 to 11 lines. The direction of the eye differs from that of the orbit, the axis of which is oblique and convergent behind, while that of the two eyes is parallel. The eye-ball (bulbus oculi) consists of several mem¬ branes, containing fluid or semifluid substances, denomi¬ nated humours. The external and strongest is the sclerotic, with the cornea enchased in its anterior aperture ; next is the choroid and retina; and the iris, a circular membrane, with an annular aperture, is placed transversely across, dividing the cavity into anterior and posterior chambers. The humours are the vitreous, the crystalline lens, and the aqueous humour. The sole- The sclerotic, sometimes named cornea opaca, in contra- rotic. distinction to the clear cornea, is shaped like a spherical shell, truncated before, and is estimated to occupy about four fifths of the globe. Its exterior surface is covered by the adipose matter of the orbit behind, and by the tendons of the muscles of the eye and the ophthalmic conjunctiva before. Its inner concave surface is lined by the choroid coat. In its anterior opening, which is about six or seven lines diameter, the cornea is enchased by imbrication of the sclerotic; and in a posterior opening about one and a half line in diameter, the ophthalmic end of the optic nerve is fixed. It is fibrous in structure, becoming trans¬ lucent when immersed in oil of turpentine. Its vessels are generally colourless, and it appears void of nerves. I he cor- The cornea, often named the clear or transparent cornea (cornea lucida), to distinguish it from the opaque cornea or sclerotic, which was supposed by the old anatomists to be of the same nature, is a segment of a smaller sphere than that of the sclerotic, attached to its anterior aperture, and occupying the anterior fifth of the eyeball. Before it is covered by a thin pellicle continued from the conjunctiva, behind by the anterior part of the membrane of the aque¬ ous humour; and its circumference is inseparably enchas¬ ed within that of the anterior aperture of the sclerotic. I he cornea consists of several concentric layers of transpa¬ rent homogeneous matter, void of vessels or nerves, closely united, but separating and becoming opaque after death. The choroid coat (tunica choroides) lines the inner sur- Special face of the sclerotic, to which it adheres loosely, except at Anatomy, the insertion of the optic nerve, where it has a posterior opening, yet may be easily detached. The margin of its -f antenoi opening, which is large, adheres to the ciliary cir¬ cle and processes, and appears to be continuous with the ins.. The outei suiface is covered by a brownish-black viscid matter, which partly adheres to the inner surface of the sclerotic. The inner surface, over which the retina is extended without adhesion, is covered by the same brownish-black matter; but of this the retina receives none, as the sclerotic. The choroid is a thin membrane, of a grayish colour when deprived of its brown pigment, trans¬ lucent, homogeneous, and, so far as observation goes, void of fibres, but liberally supplied by minute blood-ves¬ sels, partly from the long, chiefly from the posterior cilia- ries, which, dividing on its outer surface into numerous ramifications, mutually approximate, and anastomosing, form a network of quadrilateral and trapezoidal meshes. The tunica Ruyschiana is imaginary, unless this arrange¬ ment of capillary vessels be such. From these vessels is derived the brownish-black mat- Pigm»n- ter (pigmentum nigrum) with which the retinal surface of turn m- the choroid is covered. Its appearance on the convex orSrum* sclerotic surface is the effect of cadaveric transudation. The nature of this colouring matter is imperfectly known. When first secreted it is brown, but becomes black succes¬ sively as it continues. It is not affected by the action of light or caloric, and undergoes no change from the opera¬ tion of the mineral acids, aqua potassce, ammonia, and al¬ cohol. It appears to consist chiefly of carbonaceous mat¬ ter. Menghini asserts that he has obtained from it minute particles of iron attracted by the magnet. The anterior orifice of the choroid is firmly connected Ciliary cir- to a thick ring of grayish pulpy substance, and forming cle. the point at which the sclerotic and cornea without, and the iris within, are united. This ring, named the ciliary circle (ligamentum ciliare), is readily detached from the sclerotic. Its structure is unknown. Posterior to this is a range of prominent minute bodies, Ciliary with free extremities, lying over the crystalline lens, va-P1-0^856*5* rying in number from seventy to eighty. These are the ciliary processes (processus ciliares). They are trilateral- prismatic in shape, about a line and a half long, more dis¬ tinct and longer in the human eye than in those of most brute animals. Their intimate structure is not very well known ; but they are highly vascular, and their vessels ap¬ pear to be capable of occasional erection. (Plate XXX. fig- 4.) Anterior to the ciliary circle is the iris, a circular mem-The iris, brane, placed in the transverse vertical position, with an¬ terior and posterior surfaces, and a circular opening in the centre. The exterior ciliary margin (annulus major) is attached, as already stated, to the ciliary circle. The inner or pupillar (anmdus minor) is free, and forms what is named the pupil of the eye. The anterior surface is marked by a variety of colours, blue, gray, or black, brown, or that peculiar brownish-black named hazel, and which are not unfrequently allied with the tints of the skin and hair. The same surface presents radiating lines, which pass from the small to the large circle diverging. Both appearances are produced by vascular arrangement. The posterior surface of the iris, which has been distin¬ guished as a separate membrane under the name of uvea, is covered by the same dark-coloured matter secreted by the choroid, generally more abundant, and of a deeper tint, than the pigment of that membrane. When this is removed by washing, the observer recognises the radiated streaks impressed by the ciliary processes. (Fig. 4.) 44 A N A 1 Special The different characters of these two surfaces have in- Anatomy. duced some anatomists to distinguish the iris into anterior and posterior membranes. Though it has some thickness, uf the iris ’s Per^iaPs a fanciful refinement. The anterior sur¬ face, which is continuous with the membrane of the aqueous humour, is different from the posterior, which is continuous with the ciliary circle and choroid. The struc¬ ture of the iris is chiefly vascular, and its vessels have an Its erectile erectile arrangement. The long ciliaries, from which b\ stem. these vessels are derived, divide each at the ciliary body into two branches, which divaricating at obtuse angles, unite with several of the anterior ciliaries, and form with them, beyond the ciliary ligament at the large circum¬ ference of the iris, an arterial circle. From this arise smaller branches, which, crossing, unite and form within this a second smaller arterial circle, midway between the ciliary and central margin ; and from the concavity of this proceed very minute vessels, which radiate in a flexuous manner, and converge towards the pupil, where, anasto¬ mosing most minutely, they form a third circle—the mar¬ ginal ring of that aperture. Pupillary It is chiefly in the middle and inner anastomosing cir- contrac- cles that the vessels assume the erectile arrangement; and tions, and on circumstance, and not on that of muscular fibres, their true go 0ften) g0 positively, so inconsistently, and so erroneous¬ ly maintained to exist in the iris, does the mobility of that singular membrane depend. On exposure to direct or bright light, on the application of vinegar, alcohol, or any stimulating substance to the eye, and during the presence of inflammation, the erectile capillaries, distended with blood, are elongated, and necessarily contract the pupillary aperture. In the dark, under the influence of henbane (hi/oscyamus niger), deadly night-shade (atropa belladon¬ na), and some other narcotics, and when the retina is in¬ sensible, these vessels seem to lose their faculty of dis¬ tension, and, perfectly empty and shrunk, allow the pu- pillar margin to approach the ciliary. The retina. The retina, which is the third and internal tunic, is of the same shape as the choroid, thin, like cobweb, whit¬ ish, translucent, inclining to transparent, and very deli¬ cate. Its extreme tenuity and looseness from the choroid causes it to collapse unless inspected under water, when it may be unfolded and expanded for examination. Its outer surface is covered by a very delicate membrane, visible only in a very recent eye, discovered by Mr Ja¬ cob of Dublin. It is almost void of red vessels, unless at the part where the optic nerve enters, where one or two from the central artery may be seen. The others are colourless. The assertion that this membrane is an ex¬ pansion or production from the optic nerve, seems to be gratuitous; for it bears no resemblance to nervous mat¬ ter, or to the appearance of the optic nerve. It appears to be simply a peculiarly delicate transparent web, fitted to receive the impressions of luminous rays, and to communi¬ cate them to the optic nerve, with which it is continuous. Spot of So- On this membrane, about two lines on the temporal side emmering. 0f the optic nerve, and in the axis of the ball, is a circular yellow spot {macula lutea), from about a line to a line and a half in diameter, with a minute point or hole in its centre {foramen centrale). At this part the retina is much thinner than at any other; and even in the most recent eyes it presents loose folds, which Bichat regards as ca¬ daveric. The yellow spot and its central hole are seen in none of the mammalia except man and the monkeys. Vitreous The vitreous humour, occupying about three posterior humour, fourths of the eye, is spherical and convex behind and on its lateral circumference, but concave before for receiving the posterior part of the crystalline lens. Contiguous only to the retina, it is attached to the coats by the branch sent O M Y. from the central artery to the lens. It is transparent, and Special consists of two parts, an investing membrane, the hyaloid {membrana hyaloidea), and inclosed fluid. This membrane ... is not single, but, sending numerous partitions from its in-niembrane. ner surface, forms an assemblage of cells in which the fluid is contained. These facts may be demonstrated by inci¬ sion, bruising the humour, bv congelation, or by boiling it. Before, at the outline of the lens, this membrane di¬ vides into two folds, one of which is stretched before the capsule, and the other behind. The trilateral-prismatic space resulting from this separation is completed by the capsule, and forms the circular canal of Petit, which is without fluid, and which is demonstrated by inflation. On the anterior fold the ciliary processes are stretched. The structure of the hyaloid membrane is little known ; but it is believed to consist of exhalant arteries and coloui'- less veins. The hyaloid fluid may be separated from the mem-Hyaloid brane either by incisions or compressing it between two fluid, folds of linen. It then has the appearance of a clear but somewhat viscid fluid, like gum diluted with water. Though rendered slightly turbid by boiling water, acids, and al¬ cohol, it does not coagulate,—a phenomenon which is to be ascribed to the small proportion of albumen which it contains. According to the analysis of Berzelius, 100 parts contain 98*4 of water, ’16 of albumen, 1*42 of mu¬ riates and lactates, and only j^th of a part of soda. The crystalline lens, which is transparent and shaped Crystalline like an oblate spheroid, is situate in the posterior chamber, lens, and in the anterior depression of the vitreous humour, to which the convexity of its posterior surface corresponds. Before also it is prominent and convex ; and it is partial¬ ly covered by the free extremities of the ciliary processes. It consists of two parts, an inclosing capsule and a lens proper. The capsule is usually distinguished into anterior and Capsule, posterior walls, both covered by hyaloid membrane, both transparent, and both firm and resisting. By boiling wa¬ ter, alcohol, or the acids, it is rendered opaque, whitish, and horny ; and it becomes yellow by contact with the air. The lens, which is perfectly transparent, consists of two portions; an exterior, peripheral, thick, soft, adhesive, and easily removed; an interior, central, solid, and consisting of concentric plates. Both are indurated and rendered opaque by boiling water, alcohol, and dilute acids; but the central nucleus is the firmest. When dried in the air it becomes yellowish, but retains its transparency, and may be preserved for years. These phenomena are to be ascribed to the presence of a peculiar form of albumen. According to the analysis of Berzelius, 100 parts of the substance of the lens consist of 58’ of water SS’O of pe¬ culiar matter, chiefly albuminous, 2*4 of muriates, lactates, and animal matter soluble in alcohol, 1*3 of animal matter soluble in water, and 2*4 of membrane. The lens possesses a high refracting power; and its chief use is to concentrate the luminous rays within the eye, so as to represent distinctly the image of visible ob¬ jects on the retina. Spherical and transparent in early life, it is flattened and acquires a yellowish tint in old age. Between the capsule and lens is found occasionally a fluid which has been named liquor Morgagni. It appears to be the effect of transudation. On the structure of the lens, whether organic or not, anatomists vary. Vessels have not been recognised in it; and the most rational view is, that it is the product of an organic action probably in the capsule. The aqueous humour is contained in the anterior cham-Aqueous ber, and in that part of the posterior which surrounds thehumour* anterior surface of the lens and vitreous humour. It con- ANATOMY. 45 Ocular muscles. Special sists of 98*10 parts in the 100 of water, a trace of albumen, Anatomy, and about 2 parts of muriates and lactates of soda. It is contained in a membrane, which lines the posterior sur¬ face of the cornea, and is supposed to cover the anterior surface of the iris. This, however, is questionable. In 1768 a membrane of this kind was described by Demours and Descemet, both of whom claimed the discovery with great eagerness and some animosity. These rival anato¬ mists appear to have forgotten that the aqueous humour may be secreted as well by the cornea and iris as by a proper membrane. The relation of the coats and humours of the eye to each other may be understood by the diagram (fig. 3, Plate XXX.), where A is the anterior chamber, P the pos¬ terior, L the lens, and c, c the ciliary processes. The other parts are easily understood from the foregoing de¬ scription. The eye is supplied with blood chiefly by the ophthalmic artery. The eyeball, thus constituted, is moved in different directions by six muscles, is moistened externally by fluid secreted from a particular gland, and is protected from ex¬ ternal bodies by the eyelids and their appendages. Of the muscles, four are straight and two oblique. The former (attollens, depressor, adductor, abductor'), attached to the margin of the optic hole, and terminating in tendons inserted into the superior, inferior, nasal, and temporal parts of the eyeball, raise, depress, adduct and abduct the organ. Of the two latter, the superior oblique (troch- ledris), which is attached to the margin of the same hole, passes through a pulley-like cartilage at the inner margin of the vault of the orbit,and is inserted into the internal region of the ball, rolls the eye forward and inward, and turns the pupil outwards and downwards ; while the inferior oblique, attached to the orbitar process of the superior maxillary bone, and inserted between the adductor and the optic nerve, rolls it forwards and turns the pupil upwards. These muscles, which occupy the apex of the orbit, are sur¬ rounded by a thick cushion of fat, on which the eyeball rolls in its movements. (Plate XXXIII. fig. 6.) In the hollow, at the outer temporal region of the or¬ bitar vault, is placed the lacrymal gland, a granular gray¬ ish body, about the size of a bean, consisting of lobules, with arteries in the intermediate furrows, derived from a branch of the ophthalmic, and accompanying veins. (Plate XXXIII. fig. 5 and 7, G, g.) These constituent lobules have been represented, on the authority of Steno in the ox, and the elder Monro in the human subject, to ter¬ minate in 7 or 8 minute excretory ducts, opening on the conjunctiva. In man, however, they were sought in vain by Duverney, Morgagni, Haller, and Zinn; and neither Portal nor Bichat have been able to satisfy themselves of the existence of these ducts. It is nevertheless certain that the lacrymal gland secretes the tears, and that the latter issue from its lobules. The eyes are covered anteriorly by two musculo-mem- branous folds named the eyelids (palpebrce), attached to the margins of the orbit, and forming by their free mar¬ gin the palpebral opening, with commissures at each angle (canthus nasalis, et canthus temporalis'). The upper eyelid, which is large, is bounded above by the eyebrow {supercilivm), a cutaneous eminence, arched transversely, covered with hairs, and with the corrugator supercilii attached to its nasal end. Between each eye¬ brow is a smooth space, named the glabella or mesophryon. Into the upper eyelid the levator (fig. 5, L) is inserted. Each eyelid consists of skin externally, mucous mem¬ brane within {conjunctiva), intermediate cellular tissue, muscle, and a fibrous membrane, attached by one margin to the base of the orbit, and terminating by the other in Lacrymal gland. Eyelids. the tarsal fibro-cartilages. These are crescentic bodies Special placed in the free margin of the eyelids, and by their Anatomy, firmness and elasticity giving the requisite tension to the eyelids when the orbicular muscle acts, or the levator is'1'^8! and relaxed. The cutaneous border of the tarsi is occupied^ an by a range of short, firm hairs, named the eyelashes {ci¬ lia). In the mucous borders are the orifices of the tarsal or Meibomian follicles, of the same character as the mu¬ ciparous follicles generally. These are placed in the sub¬ stance of the eyelid, beneath the conjunctiva, and behind the tarsal fibro-cartilages. From the inner surface of the eyelids the palpebral conjunctiva is continued over the anterior part of the sclerotic and cornea, forming the oph¬ thalmic conjunctiva. In the nasal angle is lodged a minute red body, named Caruncle, the caruncle {caruncula lacrymalis), chiefly consisting of filamentous tissue and vessels covered by mucous mem¬ brane ; and behind this is a fold of the membrane, which has been named membrana nictitans, large in the lower animals, but often so imperfect in man as to be merely rudimentary. At the nasal end of each eyelid is a minute capillary Lacrymal orifice which leads into a horizontal canal, terminating in orifices, a membranous sac lodged in the depression of the lacrymal bone. These orifices, which are named the puncta lacry- malia {p,p, fig. 5), are the superior or palpebral openings of the lacrymal sac and passages, the lower aperture of which is found in the inferior nasal meatus. The tears effused from the lacrymal gland at the temporal region of the orbit are carried, by the frequent action of the orbicular muscle, over the ball, till they reach the nasal angle, where they are gradually absorbed by the capillary orifices of the. puncta, and conveyed into the sac, and eventually to the nose. The eye derives nerves from six different sources, all Ocular of which, however, maybe distinguished into three classes,nerves* the sensitive, motive, and entrophic nerves. The first consists of the second, optic or the proper visual nerves. The second class comprehends the third, fourth, and sixth nerves, of which the third or oculo-muscular are distributed to the levator palpebrce superioris, the attollens, the adduc¬ tor, the depressor, and the obliquus inferior; the fourth is entirely distributed to the obliquus superior; while the sixth pair are confined to the abductor. The third class of nerves is derived from the ophthalmic or quadrilateral ganglion, which is formed chiefly from the junction of a sub-branch of the naso-ocular branch of the first or oph¬ thalmic division of the fifth pair, with a small branch of the third nerve. From this arise a small superior cluster of three nerves adhering to the optic, and a large inferior cluster of eight or ten nerves, which quickly join the ciliary arteries, and are with them distributed in the ciliary circle and posterior part of the iris. (Plate XXXHI. fig. 7.) From the other branch of the naso-ocular nerve, the caruncle and lacrymal canal, with the orbicular muscle and epicranius on the one hand, and the lacrymal gland on the other, receive nervous filaments. SECT. III.—THE ORGAN OF HEARING; THE EAR. The organ of hearing consists of the auricle or external ear, with the ear-hole; the middle ear, including the tym¬ panal cavity and its appendages; and the internal ear or labyrinth. The auricle is a fibre-cartilaginous substance, moulded Auricle, into a conchoidal shape, covered by skin, attached to the cranium by ligaments, and susceptible of motion by muscles. It is common to distinguish in it the following parts. The helix, a semicircular eminence above the ear- hole ; the groove of the helix below it; the antihelix, an eminence commencing in the groove by a superior, broad, 46 ANATOMY. Special oblique portion, and an inferior, narrow, horizontal one; Anatomy, the fossa navicularis; the tragus, an anterior eminence below; the antitragus, a smaller eminence behind; the lobule, a pendulous body at the base behind; and, lastly, the concha, a deep conoidal cavity leading to the ear-hole. The latter is a canal about 10 or 12 lines long in the adult. Twisted at first obliquely forward and upward, it bends slightly backwards and downwards, forming a convexity of incurvation above, and a concavity below. Though the extremities are large, the middle is contract¬ ed ; and it cannot be termed cylindrical, for its section is elliptical or oval. The structure of this tube is fibro-car- tilaginous externally where it adheres to the bone, lined by skin passing into mucous membrane, and occupied by minute follicles (glandulce ceruminoscc), which secrete the wax (cerumeri) formed in this canal. The nature of this secretion is imperfectly known. Though, like oil, it stains paper, it is partly soluble in tepid water, and forms with it a yellow emulsion. It is secreted at first fluid, and acquires consistence by exposure to air and admixture with dust. Alcohol has little influence on it. The in¬ ternal extremity of the auditory canal is bounded by the vertical membrane of the tympanum. Tympanal Within this is the tympanal cavity, a space of an irre- cavity. gular cylindrical shape, directed obliquely, nearly in the axis of the pyramidal portion, in the base of which it is contained. This cavity is shut up externally by the ver¬ tical tympanal membrane (membrana tympani), and is bounded within by the bony partition which separates it from the labyrinth. The membrana, which is oval-shaped, or nearly round, and attached to the margin of the mea¬ tus externus, is directed obliquely downwards and inwards, and is so delicate that it is difficult to determine its struc¬ ture in the human subject. In the elephant, however, and other large animals, it presents radiating fibres, which are believed to be muscular (Plate XXXVII. fig. 14) ; and Sir E. Home represents it as such not only in the elephant and whale, but in the human subject. The outer part is evidently a sort of epidermis, continuous with that of the canal; the inner is a mucous epidermis, continuous with that of the tympanal cavity; and between these the mus¬ cular fibres are interposed. Eustachian The tympanal cavity communicates behind with the tube. mastoid cells, and before and internally by the Eus¬ tachian tube, with the pharynx. This tube is estimated to be two inches in length, of which one and a half is in the bone of the pyramid, and about half an inch at its extremity, with the upper side completed by carti¬ lage. Narrow at the tympanal end, it becomes wide and capacious towards the pharyngeal, and presents at length a free open extremity, forming a fissure at the upper and lateral part of the pharynx. The cartilaginous end is covered by mucous membrane continuous with the pha¬ ryngeal, and is surrounded by the peristaphylini, the action of which is believed to separate the walls of the aperture. Within the tube, and towards the tympanal end, this mem¬ brane parts with its pharyngeal spongy character, and be¬ comes thin and semitransparent where it lines the bone. The same kind of membrane, partaking of the characters of periosteum and mucous, is continued over the tympanal cavity, and into the mastoid cells. Muscle of Above the Eustachian tube is a thin osseous plate, which the malleus separates it from a small canal, convex below, concave and groove, above, and which, commencing in the fissure between the squamous and pyramidal portions, terminates in the tym¬ panal cavity. In this canal is lodged the internal muscle of the malleus, one of the tympanal bones. Tympanal These are four in number, very minute, and denomi- oones. nated, from their mechanical figures, the hammer (mal¬ leus), the anvil (incus), the lenticular or round bone (os Special orbiculare), and the stirrup (stapes). Of these the ma//ews is Anatomy attached to the vertical membrane by its handle, while its head is articulated with the body of the incus. The latter presents two limbs or branches, to the larger of which the stapes is articulated by the interposition of the lenticular bone; while the base of the former rests on the membrane of the foramen ovale. These articulations are secured by cap¬ sules, which allow the bones to move freely on each other ; and for this purpose the stapes is provided with one muscle, and the malleus with two, an internal already mentioned, and an external passing from the spinous process of the sphenoid bone to the slender process of the malleus. On the motions of these, however, and their part in the pro¬ cess of hearing, we have only conjectural statements. The internal bony wall of the tympanal cavity presents Foramen two apertures and a convex intermediate eminence. Of ovale, the apertures, the first, which is named the oval or vesti-fe™jftra bular aperture (foramen ovale, fenestra ovalis), is situate °'a 1S' above, oval transversely, with its great diameter horizontal antero-posterior. It communicates with the vestibule, but is closed bv a fine membrane, to which the base of the stapes is fixed, and for the insertion of which its margin is grooved. The oval aperture is bounded above by a round Promon- prominence, corresponding within to the Fallopian aque-tory. duct, and below by a large convex eminence named the promontory (promontorium), which indicates the situa¬ tion of the cavity named the vestibule. Before and above the promontory is the extremity of the thin osseous plate which separates the Eustachian tube from the canal of the internal muscle of the malleus; and behind is an oblique cavity, which is placed between the lower entrance of the mastoid cells and the pyramid. Below the promontory is the round or cochlear aperture (foramen rotundum, fenestra rotunda), trilateral in early life rather than round, and still preserving in the adult the tendency to this shape ; smaller than the oval, and directed backwards and out¬ wards. The round aperture is shut by a membrane, the direction of which is oblique to that of the tympanum, and one side of which is towards that cavity, while the other forms part of the cochlea. At the upper part of the tympanum is a triangular-Mastoid shaped opening, which leads into a rough short canal, cells. j terminating in the mastoid cells. These are analogous to the cells of the ethmoid, sphenoid, and occipital bones. They are lined by fibro-mucous membrane, and their use is to afford a posterior sonorous apartment for the vibra¬ tions produced in the tympanal cavity. Near this triangular opening is a small bony process named the pyramidal, in which is a canal for the fleshy part of the stapedius, while the tendon issues from its orifice. Near the base of the pyramidal process is the hole by which the nerve of the tympanum (chorda tympani) passes through the glenoid fissure. The labyrinth consists of the vestibule, three semicircu-Labyrinth, lar canals, and the cochlea. By removing the stapes and stapedial membrane the Vestibule, oval aperture is opened, and communicates with the vesti¬ bule. This cavity, which is irregular in shape, about the size of a grain of barley, is bounded without by the tym¬ panum, within by the internal auditory canal, before by the cochlea, behind by the semicircular canals, and above and below by the solid bone of the pyramid. It is lined by a membrane common to the whole labyrinth. Besides the oval aperture by which it is separated from the tympa¬ num, it has, above, the two anterior openings (ampullulce) of the superior vertical and horizontal canals ; behind, the two openings (ampullulce) proper to the posterior verti¬ cal and horizontal canals, and the common opening of the ANATOMY. Special two vertical canals; and before and below, the orifice of the Anatomy, external scala cochlea. There is still another aperture, which leads into a canal Aqueduct discovered by Cotugno, named the aqueduct of the ves- tibule ami" tibulc- This, which, though distinct in some subjects, is aperture, almost imperceptible in others, is near the common orifice of the vertical canals; and from it the aqueduct proceeds first upwards, where it is narrow, then backwards and downwards, widening, and terminates in the fissure on the posterior surface of the pyramidal portion. Semicircu- The semicircular canals, situate behind the vestibule, lar canals. are three in number, two vertical and one horizontal. Of the former, one is superior, inclosing by its curvature the substance of the pyramid, and forming a convexity in the adult, very distinct in the foetus ; while the other, which is posterior but inferior, is placed with its plane correspond¬ ing to that of the posterior surface of the pyramid. The third is placed horizontally between the other two, form¬ ing a curvature with the convexity towards the base of the pyramid. (Plate XXXIII. fig. 8, 9, and 10.) Though denominated semicircular, these canals are larger than semicircular, and may be compared to hollow cylinders, incurvated so as to form large circular segments. Each canal has an enlarged extremity named ampullula ; and as these two vertical canals have one in common, there are five ampulluloe. They are lined by the common la¬ byrinthine membrane, and contain a pellucid fluid. Cochlea. The cochlea, which forms the third part of the labyrinth, is a conical canal turned spirally within itself, so that its base is at the lower part of the vestibule, and its apex at the anterior side of the pyramid, with the orifices for the auditory nerve inclosed in the centre of its turns, while the convexity is directed towards the lower margin of the pyramid. The cochlear canal is divided longitudinally by a thin sharp-edged plate, half bony half membranous, into two independent cavities, the superior of which communi¬ cates with the vestibule, while the inferior is bounded by the membrane of the round aperture. These cavities are distinguished as the vestibular and tympanal {scala vestibuli and scala tympani) respectively. At the top they termi¬ nate in a common cavity named the funnel {infundibulum). Both are lined by a delicate membrane, in which are con¬ tained the ramified filaments of the eighth or auditory nerve. fPlate XXXIII. fig. 10.) ;Aqueduct In the tympanal scala, near the round hole, is a minute of the aperture leading to a narrow canal, which gradually en- cochlea. larges as it ascends, till it terminates by a slit on the pos¬ terior surface of the pyramidal portion, as formerly men¬ tioned. This is the aqueduct of the cochlea, first describ¬ ed, like that of the vestibule, by Cotugno. Blood-ves- These different cavities are supplied with blood chiefly sels ot the from minute branches of the auditory, a vessel generally derived from the basilar trunk or the vertebral arteries. From the meningeal artery also minute branches enter the auditory canal, and anastomose with those of the auditory artery; and the internal carotid sends to the membrane of the tympanal cavity a branch, the capillary ramifica¬ tions of which anastomose with those derived from the pharyngeal, transmitted by the walls of the Eustachian tube. uditory The eighth or the proper auditory nerve enters the coch- erve- lea by several minute apertures in the internal meatus, and is divided into two fasciculi, of which the posterior and largest is expanded in the form of soft pulpy brush-like filaments, like a hair-pencil, in a pellucid fluid, in the coch¬ lea ; while the smallest, which is anterior, is distributed partly to the bottom of the hemispherical cavity of the vestibule, partly to the beginning of the spiral lamina. (Fig. 10.) The tympanal cavity is chiefly for the purpose of con- Special veying and augmenting the intensity of sonorous vibra- Anatomy, tions, while the shape of the auricle is supposed to collect them. But of the mechanism of its operation we know nothing satisfactory. The essential part of the organ of hearing is the labyrinth. SECT. IV.—THE ORGAN OF TASTE. It is impossible to define the exact limits of the sense of taste. More or less diffused over the cavity of the mouth, it is particularly confined to the tongue and palate. The former, nevertheless, is remarkable for being a mus¬ cular organ, which combines with the faculty of taste the power of prehension and transmission of the alimen¬ tary articles both during and after mastication, and is further an essential agent in the faculty of articulation. It is requisite, therefore, to give a short account of the mouth, the palate, and the tongue. a. The mouth is the cavity formed by the lips before, the The pharynx and isthmus faucium beMvad., the palatine vault mouth- above, the intramaxillary membrane and muscles below, and on the sides by the cheeks. Its horizontal direction may be regarded as one among other proofs of the neces¬ sity of the erect biped attitude. The mouth is lined by a mucous membrane, soft, spongy, red, and vascular. It may be traced from the inner or alveolar surface of the lips to the inner surface of the cheeks on each side over the gums, where it is continuous with that of the alveolar folliculi, over the inner surface of each maxillary ramus, and the attached muscles and glands below, until it is identified with that of the tongue, and above over the palatine vault back to the uvula. In these several points, though its organization is the same, its mechanical arrangement varies considerably as the parts are fixed or movable. Thus, on the palatine vault and at the gums it is tense, and adheres pretty firmly to the fibrous layers forming the periosteum of these parts. In the angular space between the lips and gums, however, in that between the inner surface of the alveolar arch, and all over the lower part of the mouth, where it is connect¬ ed to the inferior surface of the tongue, it is extensive, loose, moves easily over an abundant layer of filamentous tissue, and is generally disposed in irregular folds. Ad¬ hering to the internal spine of the lower jaw, a fold or du- plicature containing condensedfilamentous tissue is reflect¬ ed, to be attached to the median line of the tongue, and forms the frenum of that organ. In all points it abounds with muciparous follicles. It also presents on each side of the tongue the orifices of the sublingual glands. The mouth has two outlets, an anterior or facial formed Outlets of by the lips (labia), and a posterior or pharyngeal formed by the velum palatinum and its appendages. The lips are musculo-membranous folds, attached all The lips, round to the superior and inferior jaw-bones, above and below the alveolar arches, and parted by a transverse opening or fissure into upper and lower, with right and left commissures or angles (canthi). In the Negro race they are particularly bulky and flaccid, with their free margins (prolabia) much everted; but in the Asio-Euro- pean they are thinner, and more constricted. Each lip consists externally of skin continuous with that of the face, internally of mucous membrane continu¬ ous with that of the mouth, with interposed filamentous tissue and muscles, well supplied by blood-vessels and nerves. The point of union between the skin and oral mucous membrane is marked by a rounded edge, covered by a thin, vermilion-red, soft and delicate pellicle, extending between ANATOMY. 48 Special each canihus. This, which is sometimes named the lips Anatomy, proper (labiola), is the prolabium. The blood-vessels dis- '^~v~s^/tributed to this part of the lips have an erectile arrange¬ ment. The marginal region of the lips between the skin and mucous membrane is occupied by the orbicular muscle. Above are the labial ends of the common levators {levator labii superioris alceque nasi), the proper levators {levator labii superioris), the small zygomatics {zygomaticus minor), and the naso-labial {nasalis labii superioris). Below are the two depressors of the lower lip. At the angles are placed the buccinators, the depressors of the angles, the canine muscle {levator anguli oris), and the large zygo¬ matics. The lips are supplied with blood from the branches of the external carotid. The external maxillary sends a large branch over the angle of the inferior jaw, upwards and forwards to the labial commissures on each side. This vessel, which is generally named the labial, sends of! two, a superior and inferior labial, which are subdivided into numerous minute branches, anastomosing freely with each other, and with the submental and inferior dental branches. They open freely into the capillary veins, con¬ stituting a species of erectile tissue. The lips derive their nerves partly from the superior maxillary, partly from the anterior or mental division of the inferior maxillary, with anastomotic communications from the 8th or facial nerve. Soft palate, b. The posterior or pharyngeal outlet of the mouth {isth¬ mus faucium) is formed by the movable or soft palate {velum palatinum), a membranous fold attached to the posterior margin of the palatine quadrilateral bones, and hanging with its free margin downwards. This curtain, which has two surfaces, an anterior or oral and a posterior or pharygneal, is shaped like a double arch, meeting on the mesial plane, where it terminates in an elongated conical prominence, sup¬ posed to resemble a grape suspended by its stalk, and de¬ nominated therefore uvula {arucpuXri), but which, with the lateral arches,bears a closer resemblance to the descending cusp of a Gothic window. From this central process the arch rises on each side; and when it passes to the outer edge of the palate-bone on each side, it is supported by two musculo-membranous vertical columns, united at the top, but separating and forming an intermediate cavity, in which the tonsil on each side {amygdala) is contained. The palatine curtain consists of two folds of mucous membrane, with interposed filamentous tissue and muscu¬ lar fibres. The anterior mucous membrane is of the same character with that of the mouth, with which it is con¬ tinuous. The posterior, which is continuous with the nasal mucous membrane, partakes of the charactersiiof that tissue, and is redder and more vascular. These two meet in the lower margin of the velum, and pass into each other. Both are well supplied with mucous follicles, but the anterior or oral division most copiously. These mucous membranes rest on filamentous tissue; and beneath this we find, in the middle, the levator or azy¬ gos uvulce, and on the sides the levator of the soft palate {peristaphylinus internus), which are expanded in the ve¬ lum. The anterior pillar consists of mucous membrane enveloping the fibres of the constrictor isthmi faucium; the posterior incloses those of the pharyngo-staphylinus ; and both expanding into the velum, augment its thickness and regulate its motions. Between the internal peristaphylini, which are imme¬ diately below the pituitary or posterior mucous membrane of the velum and the anterior, is an aponeurotic web, connected with the circumjlexi, which, fixed to the margin of the palatine vault, tends to consolidate the velum. The free margin of the velum forms the upper boundary of the posterior or pharyngeal opening of the mouth, Special while the upper surface of the base of the tongue forms Anatomy, the lower boundary. The size of this opening, which is'v^~v^N^ usually named the isthmus of the throat {isthmus faucium), varies according to the state of the velum and its uvula. In the act of deglutition the velum and uvula are raised by the peristaphylinus internus and azygos uvulce, and the whole curtain is constricted by the constrictor isthmi fau¬ cium and pharyngo-staphylinus. In the act of vomiting it is forcibly drawn up against the posterior nasal openings by these muscles ; but notwithstanding this, matters from the stomach are occasionally projected through the nostrils. In singing on false notes the uvula is progressively ele¬ vated, as the voice ascends. In the space between the anterior and posterior pillars are contained the tonsils {tonsillce, amygdalae), bounded above by the commissure of the pillars ; below by the la¬ teral part of the base of the tongue, where they are con¬ tinuous with the muciparous glands of that organ ; before by part of the constrictor isthmi faucium ; and behind by the pharyngo-staphylinus. The shape varies in different individuals, though their pendulous attachment gives them the oblong spheroidal or almond-like shape. They consist of several lobules, grayish, soft, and of structure similar to that of the muciparous glands of the tongue. The lobules present minute cavities, isolated or mutually communi¬ cating, in the recess of which are minute pores, the ori¬ fices of the excretory ducts, and from which a watery but viscid liquor may be expressed. In short, each tonsil may be regarded as an assemblage of muciparous glands, destined to secrete fluid for lubricating the throat during the process of deglutition, when it is most abundant. The chops {bucccc) or lateral walls of the mouth con¬ sist externally of skin, internally of mucous membrane and of an intermediate layer of muscles imbedded in abundant filamentous and adipose tissue. The cutaneous covering is in general thin, soft, and pe¬ culiarly smooth, with a minutely distributed and abun¬ dant capillary system, which approaches in its characters to the erectile. Beneath the cutaneous covering is the zygomaticus ma¬ jor, the only muscle proper to the cheek, resting on a thick layer of fat; below this is the buccinator, perforated by the parotid duct; and to the filamentous tissue inside, the buccal mucous membrane, furnished with numerous muciparous follicles, adheres. The orifice of the parotid duet is seen opposite the second molar tooth of the supe¬ rior jaw. c. The tongue is a longitudinal muscular organ, invested The by a mucous membrane provided with numerous papillae, tongue, attached behind to the hyoid bone, below to the mu¬ cous membrane of the mouth, and free above and before. It is shaped like a flattened cone, and is distinguished into a base and tip {apex), an upper and a lower surface, and two sides. The base is somewhat thick and broad, but becomes thin and narrow near the hyoid bone. From about 1 inch anterior to this, however, to near from the tip, the thick¬ ness and breadth are nearly uniform. The tip {apex) is flat and rounded or paraboloid in ordinary circumstances, but may be made by muscular action to taper to an angu¬ lar point. The upper surface, which is free, presents the lingual mucous membrane divided into right and left halves by a superficial furrow. On this, near its posterior end, is a depression, variable in size, named the foramen caecum, in which are contained the orifices of muciparous follicles. From this on each side proceeds an oblique line diverging forward, and forming with that of the opposite side an acute angle, with the angular point behind. These an- ANA'; Special gular lines, which are variable in shape and disposition, Anatomy, depend on the elevation resulting from the mucous glands s^''~v"'Sta>,at the base of the organ. The rest of the surface pre¬ sents the minute conical eminences named papillae, which belong to the mucous membrane. The lateral margins, which are smooth and void of papillae, form the transition from the upper free papillated surface to the lower, which is chiefly attached by folds of the oral membrane to the lower region of the mouth. The tongue consists of various muscles, connected by filamentous tissue, some adipose tissue, and invested by mucous membrane. Muscles. The muscles are of two orders, those common to the tongue and contiguous parts, and those proper to the tongue. The common or extrinsic muscles are, the stylo¬ glossi, between the styloid process and margins of the tongue; the hyoglossi, between the branches of the hyoid bone and the margins of the tongue; and the genioglossi, from the upper internal mental tuberosities to the lower part of the organ. The proper or intrinsic muscle (lin- gualis) consists of two parallel layers of muscular fibres running along the lower surface of the organ, and a mass of fleshy fibres irregularly arranged and mutually crossing in all directions, and intermixed with a considerable quan¬ tity of soft but elastic oleo-adipose matter. Of the lingual mucous membrane the most important circumstances are, the leathery thickness and distinctness of its corion and epidermis on the superior surface of the organ, and the papillary eminences with which it is marked. Lingual These papillae may be distinguished into three orders ; papillae, the irregular or granular at the base, the tubercular or rounded about the middle third, and the conical or point¬ ed at the apex. The granular which vary in number from 10 to 15 or 16, are of a spheroidal or ovoidal shape, and are arrang¬ ed on each side of the median furrow, obliquely behind the sides of the angle already mentioned. These bodies are evidently muciparous follicles; and it is in general easy to distinguish the orifice of the excretory duct by the eye or a moderate lens. They seem to receive fila¬ ments from the glosso-pharyngeal nerves, which enter the tongue immediately beneath these granular glands. The tubercular papillae, which are much more nume¬ rous, have rounded truncated summits, and occasionally pedunculated stalks. They are irregularly distributed towards the middle, margins, and apex of the tongue, promiscuously with the conical; and their nature is un¬ known. The conical or acuminated papillae, though occupying the two anterior thirds of the lingual surface, are never¬ theless most numerous towards its apex, where they are also smallest, and somewhat inclined forward. These papillae are asserted by the older anatomists to be the terminations of nervous twigs; and Cloquet allows them to be the expansion of the filaments of the lingual nerve. This, however, is an evident relic of the fanciful represen¬ tations of the older anatomists, and is not supported by inspection. I have examined the structure of the lingual papillae in many instances, and in none have I seen any ground for the assertion that they consist of nervous fila¬ ments. They do not even receive a larger proportion than other parts of the lingual membrane. The papillae consist chiefly of numerous minute blood-vessels, rather tortuous, and communicating directly with veins envelop¬ ed in fine filamentous tissue; and from this they derive their property of erection, while their mucous surface se¬ cretes mucus copiously. These papillae are further the seat of the white fur with which the tongue is liable to VOL. in. ’ O M Y. 4. be coated in affections of the stomach. The yellow fur Special seems to be produced from the mucous surface generally. Anatomy. The tongue is supplied with blood by the lingual ar- tenes, branches of the external carotids, and by the pala-Arteries* tine and tonsillary of the external maxillary. The blood is returned by the superficial vein, the ranine, the lingual, and submental. The nerves of the tongue are derived from three differ-Nerves, ent sources; the inferior maxillary, or third branch of the fifth pair; the glosso-pharyngeal ; and the hypoglossal. From the first it receives the lingual nerve, which, after sending filaments to the sublingual gland, the styloglossus, genioglossus, and proper muscle of the tongue, is distri¬ buted chiefly to the upper surface, sides, and apex of the organ. This is believed to be the proper gustatory nerve. From the second it receives a lingual branch, which, pass¬ ing between the styloglossus and hyoglossus, gives fila¬ ments to these, the proper muscle, and the posterior part of the genioglossus, and to the granular papillae. By means of this nerve the motions of the tongue and pharynx are made to associate. The third, which is distributed chiefly to the muscles attached to the hyoid bone, sends filaments also to the hyoglossus, styloglossus, and chiefly to the genioglossus. The hypoglossal is believed chiefly to preside over the motions of the tongue, and probably those destined for articulation. The tongue is one of the best examples in the human Uses, body, of the felicity with which a single organ may be adapted to a great variety of useful purposes. Endowed with the common sensation of tact, diffused over the bodv at large, its mucous investment is so organized that it re*- cognises readily the peculiar impressions communicated by sapid bodies. To render it more serviceable in this respect, its muscles make it an organ of prehension, and elongate, contract, inflect, incurvate, or extend it, so as to apply objects placed on its tip to the palate or any part of the mouth. By the same means it becomes an important agent in the prehension of food, and in deglutition, by transmitting the masticated food to the pharynx. Lastly, it is a most essential and necessary organ of speech, and, by the nice motions which it undergoes, enables the human race to pronounce literal sounds and articulate consonants, which without its aid would be unutterable. Of this the letters 1 and r are examples. d. Connected with the organs of taste are the salivary Salivary glands, of which there are three pairs, one on each side ofSlantls. the mesial plane; the parotid, submaxillary, and sublingual. The parotid, so named from its situation before the ear, Parotid, is the largest of all the salivary glands. It consists of two parts, the parotid proper, a large oblong mass placed in the deep angular cavity formed by the maxillary ramus and the mastoid process; and the socia parotidis, a large flat irregularly oval mass extending beneath the skin of the face. Partaking of the general characters of glandu¬ lar structure, it is supplied with blood from the external carotid, by the temporal and transverse facial; its veins open into the external jugular; and it receives numerous nervous filaments from the facial and the ascending branches of the cervical plexus. It has an excretory duct, named also the duct of Steno (ductus Stenonianus), which, quitting the surface of the gland a little above the middle of the upper margin of the masseter, proceeds horizontally over the tendinous part of that muscle, and, sinking into the filamentous adipose tissue of the cheek, perforates the buccinator, and termi¬ nates in the mouth at the level of the second superior molar tooth. The submaxillary or intramaxillary is smaller than the Sub-max. parotid. Oblong in shape, it is placed on the internal pit illary.- G 50 ANATOMY. Special of the lower jaw, bounded by the internal pterygoid and Anatomy, mylo-hyoid above, the lingual nerve, the stylo-glossus and hyo-glossus, and the external maxillary artery behind, and below by the latissimus colli and integuments. Blood it derives from the lingual and external maxillary arteries, and nerves from the lingual and the myloid branch of the inferior dental. Its excretory duct, named, from its dis¬ coverer, the duct of Wharton, terminates on the side of the frenum, in a narrow tuberculated orifice. The sub- The sublingual gland is the smallest of the three. Pa- lingual rallel to that of the opposite side, it is separated from it gland. by the base of the two genio-glossi, and rests on the rnylo- hyoideus, which separates it from the intramaxillary. Oc¬ casionally, however, these two glands communicate by a slip from the intramaxillary below the muscle. It is sup¬ plied with blood by the sublingual, ranine, and submental arteries; and its nerves proceed from the lingual and hy¬ poglossal. Its excretory ducts are manifold, and terminate either in several orifices on the sides of the frenum, or unite in a single tube, opening in the same region. The use of these glands is to separate from the blood a watery but somewhat saline and sapid fluid, which has the twofold office of preserving the gustatory membrane in its necessary moisture, and of mixing with the food during mastication. The saliva consists chiefly of water, holding in solution hydrochlorate of soda, sulpho-cyanic acid, and a minute portion of animal matter intermediate between albumen and osmazome. The presence of sulpho-cyanic acid, an active poison, is remarkable ; nor is the purpose of such an agent known. From the saline matters in this fluid the tartar of the teeth is deposited; and occasionally minute concretions are formed in the glands or their ducts. That appearing in the ducts of the sublingual forms one variety of the affection named ranula. CHAP. III. THE ORGANS OF VOICE. Voice is of two kinds, according as it consists in the mere voluntary utterance of sound, or what is named, in refer¬ ence to the animal world, cry, or in the utterance of certain peculiar modifications of this, denominated therefore arti¬ culate voice, or simply speech. Inarticulate voice is com¬ mon to all the Mammalia and Birds. By the posses¬ sion of articulate speech, however, man (/^sgo^) is parti¬ cularly distinguished from the animal world in general. These two forms of voice have two distinct organs. For inarticulate voice the larynx is placed at the superior ex¬ tremity of the windpipe; and for that of speech, to the larynx are superadded the articulating powers of the teeth, lips, and tongue. The The larynx is a tubular organ, consisting of cartilages larynx. invested by membranes, connected by ligaments, and moved by muscles. Thyroid The cartilages are five in number, the thyroid, cricoid, cartilage. tw0 arytenoid, and the epiglottis. The thyroid cartilage, which forms the anterior and lateral region, consists of two lateral halves united on the mesial plane, where they form an acute salient angle, dis¬ tinct beneath the integuments, and forming what is named thepomum Adami. The anterior surface is slightly concave, covered by the thyro-hyoideus, with an oblique line, to which the muscle now mentioned, the sterno-thyroideus, and infe¬ rior constrictor, are attached, and a posterior space covered by the two latter muscles. The posterior surface of the thyroid has in the middle a re-entrant angle, to which are attached the ligaments of the glottis and the thyro-arytamoi- dei; on the sides two plane surfaces, corresponding above to the cellular tissue of the thyro-arytcenoidei, and below to the lateral crico-arytcenoidei, and some fibres of the Special crico-thyroidei attached to this part. Anatomy. Each lateral half is quadrilateral and quadrangular. To'^>^v~s^/ the upper margin, which is obliquely sinuated like an f the thyro-hyoid membrane is attached. To the lower, which though shorter is also sinuated, the crico-thyroid membrane and the crico-thyroidei are attached. The posterior margins, which are oblique and give at¬ tachment to several fibres of the stylo-pharyngei and pa- lato-pharyngei, terminate above in an elevated pointed process incurvated inwards and forwards, connected by a ligament to the hyoid bone, and below in a similar process, shorter however and triangular in shape, and articulated by its tip with the lateral process of the cricoid cartilage. The cricoid or annular cartilage (xg/xog, annulus), which Cricoid occupies the lower part of the larynx, is a complete ring cartilage, of cartilage, narrow before, and broad and elevated be¬ hind, where chiefly it constitutes the laryngeal cavity. Convex in the middle, where it is subcutaneous, it widens laterally where the crico-thyroidei are attached ; and far¬ ther back, where it is covered by the thyroid cartilage, it presents the lateral process covered by synovial mem¬ brane for articulation with the triangular process of the thyroid. Its posterior region is broad and quadrilateral, with a ridge on the median line covered by the pharyngeal membrane only, and two depressions on each side, to which the posterior crico-arytcenoidei are attached. The inner surface, which is concave, narrow before and broad behind, is covered by the laryngeal mucous membrane. The superior margin presents before a large notch, to which the crico-thyroid membrane is fixed, laterally the insertion of the lateral crico-arytcenoidei, and behind two convex surfaces, oblique in direction, covered by synovial membrane for articulation with the arytenoid cartilages, and between which this margin is covered by the aryte¬ noid muscle. The lower margin, less irregular, descend¬ ing before, sinuated on the sides and notched behind, is united by a fibro-mucous membrane to the first ring of the windpipe. The arytenoid cartilages are two small bodies, triangu-Arytenoid lar and pyramidal in shape, placed at the posterior part cartilages, of the larynx, in the upper margin of the cricoid cartilage. In each arytenoid cartilage may be recognised a concave anterior surface for the arytenoid gland, a concave posterior surface for the arytenoid muscle, an internal surface covered by laryngeal mucous membrane, a base concave and oval, covered by synovial membrane for articulation with the cri¬ coid, and a thin, convex summit, supporting a small carti¬ lage (cornicula laryngis), invested by mucous membrane. These bodies, which are named the tubercles of Santo- The tu- rini (capitula arytcenoidum) by whom they were discover- bercles of ed, are conical in shape, with a concave base for articulat- Santorini, ing with the summit of each arytenoid cartilage, and a pointed apex incurvated inwards and backwards. To their surface, with part of the arytenoid, the thyro-arytenoid ligament is fixed, and forms the beginning of the glottis. These bodies partake of the general characters of car¬ tilage, and are invested by perichondrium. The thyroid and cricoid have a great tendency to ossification; and it is rare to find them unossified in advanced life. The epiglottis is a thin slip of fibro-cartilage, of a para- The epi- boloid shape, covered by mucous membrane, attached at glottis, its base by cellular tissue to the inner surface of the hyoid bone and the upper margin of the thyroid carti¬ lage, and by duplicatures of mucous membrane to the summits of the arytenoid cartilages. In this duplicature, The cunei- on each side, is suspended a minute wedge-like cartilagi- form carti- nous tubercle, with the base upward, named the cuneiform. ^aScs' These cartilages are articulated so as to admit of mo- ANATOMY. 51 Special tion at the points already indicated. The articu at o Anatomy. are secured by ligamentous capsules; but the most im- ^^^nortant ligament is the thyro-arytenoid, which passes from the base of each arytenoid cartilage to the re-entrant angle of the thyroid, where the fibres are mutually mixed with that of the opposite side. The thyroid moves on the cricoid, which may be regarded as the base of the or¬ gan ; and the two arytenoid move on the upper margin of the cricoid. The epiglottis is depressed oyer the laryngeal opening by the motion of the tongue in deglutition. The agents of motion in the larynx are of two kinds; 1^, those which move the whole organ in relation to the neighbouring parts; and, 2dly, those which move the com¬ ponent parts of the larynx in relation to each other. To the former class belong the sterno-thyroid, thyro-hyoid, and inferior constrictor muscles, with those attached to the hyoid bone, the elevation and depression of which the larynx follows. The second comprehends the crico¬ thyroid, the posterior crico-arytenoid, the lateral crico¬ arytenoid, the thyro-arytenoid, and the arytenoid. The connections and relations of these muscles it is super¬ fluous to detail more minutely than may be understood from the description already given of the cartilages. It is sufficient to say, that while the crico-thyroid causes the thyroid cartilage to perform a swinging motion on the cri¬ coid, the posterior crico-arytenoid draws the arytenoid cartilages back, the thyro-arytenoid draws them forwards, the lateral crico-arytenoid separates them from each other, and the arytenoid, sometimes distinguished into trans¬ verse and oblique arytenoid muscles, approximates these cartilages in different degrees, according to the act in which they are used. The several parts now mentioned are invested on the inside by mucous membrane, continuous above with that of the pharynx and tongue, and below with that of the trachea. Proceeding from the former boundary, it may be traced over the epiglottis and its gland, on the mesial plane and the thyro-arytcenoidei, and on the sides from the inner surface of the thyroid cartilage before to the outer margin and base of the arytenoid cartilages behind. At this part it rises to form two folds with rounded margins, extend¬ ing from before backwards, and forming on the outsides a cavity with the arytenoid cartilage. These folds, though occasionally named the superior ligaments of the glottis, are truly mucous membrane doubled, with interposed filamentous tissue. They form an intermediate triangular space, with the base before and the apex behind. The inner surface of this membrane, directed to that of the op¬ posite side, is concave, and forms a sort of pouch called the ventricles of the larynx (sacculi laryngis). The mem¬ brane here covers the thyro-arytenoid ligaments, over which it is tensely stretched, so as to form inferior folds, much tenser and firmer than the superior ones. These lower folds, which form a triangular interval with the base behind and the apex before, are the proper ligaments of the larynx, or vocal chords (chordoe vocales); and the in¬ termediate fissure is named the glottis, or rim a glottidis. Though this opening is triangular in the dead body, its shape varies much in the living. By the joint action of the posterior crico-arytcenoidei and the arytcenoidei trans- versi, the thyro-arytenoid ligaments maybe rendered tense, the arytenoid cartilages approximated, and the fissure of the glottis become a mere slit. Though it is impossible to adopt all the views of Do- dart regarding the powers of the thyro-arytenoid ligaments, it is certain that their tension and relaxation, with the mutual approximation of the arytenoid cartilages, are the essential agents of voice. Without the air passing through the glottis there is no voice. The glottis is also the organ by which the quantity of air admitted into the trachea is Special regulated. By means of its muscles it may be shut, andA^oiny* the breath retained, so as to fix the chest during any great effort. By contracting it, also, during coughing or forcible expiration, the air is forcibly expelled from the lungs, and necessarily carries at the same time foreign bodies. At the base of the epiglottis, in the angle between it and the thyroid, the laryngeal membrane presents several orifices, which may be traced to a cluster of follicles im¬ bedded in the submucous tissue at this part. This clus¬ ter has been named the epiglottic gland. A similar glandular body, in the anterior depression of each arytenoid cartilage, is named the arytenoid glands. Of the body named thyroid gland, situate on the sides of the upper end of the trachea, and generally referred to the appendages of the larynx, nothing is known. With the larynx it has certainly no relation. The blood-vessels of tbe larynx are the superior thy¬ roid or laryngeal, the first branch of the external carotid, and the inferior laryngeal branch of the inferior thyroid, the second branch of the subclavian artery. The nerves are derived from the pneumogastric or ner- vus vagus, and may be referred to three divisions; the internal laryngeal, distributed to the proper muscles of the larynx; the external laryngeal, distributed to the thyro-pha- ryngeus, the sterno-thyroid, hyothyroid, and crico-thyroid; and the recurrent, distributed to the laryngeal membrane, the thyro-arytenoid, and posterior crico-thyroid muscles. The division of these nerves, or of the pneumogastric, from which they proceed, is followed by palsy of the muscles, and inability to open the glottis at will, or retain it open ; and the result is dyspnoea, terminating in asphyxia CHAP. IV.—THE NERVOUS SYSTEM. The nervous system includes two general divisions, a central and a distributed. The first is collected in a single and indivisible mass, contained in the cavities of the cranium and vertebral column, and may be designated by the general appellation of brain {cerebrum). The second consists of long chords connected with some part of the central portion and with each other, and distri¬ buted in every direction through the body in the mode of ramification. These are distinguished by the name of nervous chords or nerves (nervi). SECT. I. THE BRAIN AND ITS MEMBRANES. § 1. the brain. Plate XXX. The brain may be considered as a continuous organ, con¬ sisting of three divisions;—the convoluted, the laminated, and the smooth or funicular portions. Of these divisions, which are framed according to the peculiar external con¬ figuration of each, the first part corresponds to what is called the brain proper {cerebrum); the second to the small brain {cerebellum) ; and the third to the oblong body contained in the vertebral column, and known under the name of spinal chord. The convoluted portion presents two surfaces, an outer or convoluted, and an inner or figurate. The laminated portion in like manner presents two surfaces, an outer or laminated, and an inner or central. The third has only one exterior surface. The shape of the first two divisions is like that of the cranial cavity in which they are contained, oblong sphe¬ roidal or ovoidal, with the small extremity of the ovoid be¬ fore, and the large one behind. The human brain is larger and heavier in proportion than that of any other animal. The three parts, the brain, cerebellum, and spinal chord, after being washed and 52 ANATOMY. Special emptied of blood, weigh in the adult from two pounds Anatomy, five ounces to three pounds three ounces, and at an ave- '~'*’~v~N“y,rage about three pounds; and of this the brain alone weighs two pounds. The statement of Haller, that the brain weighs five pounds, is incredible, unless it be under¬ stood of Troy weight, in which case even it seems exag¬ gerated, since of more than 200 brains weighed by Soem¬ mering, not one amounted to four pounds. The statement, that the brain of Cromwell weighed six pounds and one fourth, seems equally incredible. The specific gravity of the adult brain is to water as 1031 to 1000. This, how¬ ever, varies with age. The cerebellum weighs about five or six ounces, and is therefore about the seventh part only of the weight of the brain. General The brain (cerebrum) is divided above and before into d>-ion of tw0 lateral halves, named hemispheres (hemispfucria), the brain. rjg|it and jept) separated by a deep furrow, in which the vertical, crescentic, or dichotomous portion (falx) of the hard membrane is received. Each hemisphere is bounded by a superior or convex, an inner or plane, and an inferior convex and concave surface. The lower surface of each hemisphere, also, anatomists distinguish into three lobes, an anterior, posterior, and middle. The cerebellum is also divided into two hemispheres, separated by a middle furrow of less depth, receiving, as that of the brain, a crescentic production, smaller in size, from the hard membrane. Convolut- The exterior surface of the convoluted division is form- s^r*ace ed into eminences longitudinal and rounded, but directed braird vari°us ways> named convolutions or circumvolutions (gyri, Soemmering, Wenzel), and separated from each other by deep hollows (sulci). To see this surface, which is termed the convoluted, the vascular membrane termed pia mater (meninx tenuis) must be removed. The convoluted surface of each hemisphere may be divided into five regions : 1. The commutual or dichoto¬ mous ; 2. the lateral-superior or convex; 3. the antero¬ inferior or frontal; 4. the medio-inferior or spheno-tem- poral; and 5. the posterior or cerebellic region. 1. The commutual, plane, of a shape nearly semicircular, forms the mesial boundary of each hemisphere, and cor¬ responds to the falciform or dichotomous portion of the hard membrane (yr\\iy\ 6%Kr\oa, meninx dura), by which it is separated from the similar surface of the opposite he¬ misphere. Before and behind it extends from the supe¬ rior to the inferior surface of the brain; but a consider¬ able portion of its middle is terminated by the upper sur¬ face of the middle band (mesolobe, corpus callosum), which lies between the two hemispheres. It is contained be¬ tween the semicircular and the rectilinear margins. 2. The convex region occupies the anterior, upper, lateral, and posterior parts of the hemisphere, from their anterior to their posterior extremity, and from the semi¬ circular margin to a line which extends between these extremities along the lateral borders of the organ. 3. The antero-inferior ox frontal rests on the horizontal part of the frontal and ethmoid bones, commencing before with a curved outline, bounded behind by the curvilinear hollow named the fissure of Sylvius, and at its inner or mesial margin by the great fissure which separates the hemispheres. This inner margin presents one convolution, consisting of a longitudinal eminence, extending in the adult brain about inch from the posterior towards the anterior end of the notch. The outer furrow contains the cerebral portion of the first pair or olfacient nerves. (1,1.) 4. The medio-inferior or spheno-temporal is situate im¬ mediately behind this region, from which it is separated by the curvilinear hollow (fossa Sylvii). In the ordi¬ nary descriptions this forms the middle lobe; while the posterior part, corresponding to the cerebellum, though dis- Special tinguished by no evident limit, is with equal impropriety Anatomy, named \he posterior lobe. The whole region, from the cur-''J^~v~v“// vilinear hollow to the posterior tip of the hemisphere, may, however, be subdivided into two, the medio-inferior and postero-inferior regions of the convoluted surface, ac¬ cording as they correspond to different containing parts. 5. The posterior cerebellic region of the convoluted sur¬ face, which is plane, corresponds to the horizontal or ce¬ rebellic part of the hard membrane. The convoluted surface is formed of cerebral matter, of a gray or dirty wax colour, the surface of which is smooth and polished where it has not been rent by the removal of the membranes and their attachments. In the fur¬ rows are many minute orifices, into which the soft mem¬ brane (XeTry meninx tenuis, pia mater) transmits filamentous bodies, containing minute blood-vessels. Neither the eminences nor the hollows are uniform in number or distribution ; and in no two brains is it possible to trace any similarity in their figure, presence, or direc¬ tion, in the upper, lateral, and posterior part of the con¬ voluted surface, unless where it approaches the central or figurate surface, where a number of important objects are presented. The convoluted surface communicates with another interior surface at two parts; ls£, on the middle plane, under the posterior end of the middle band or mesolobe (corpus callosum) ; 2ri, on each side of the middle plane, at the outer margin of the fluted masses termed limbs of the brain (crura cerebri), between these limbs and the posterior end of the optic chamber or couch (thalamus opticus). This surface of the organ may be termed the central or figurate. The exterior surface of the cerebellum consists of thin Laminated portions of cerebral substance named plates (lamince), or surface of leaves (folia), placed contiguously, either parallel or con- ^ cere‘ centric, and separated by furrows of various depth. Thisbe um* surface, which may be named the laminar ox foliated sur¬ face of the small brain, communicates also with the figu¬ rate surface,—ls£, above on the middle plane, between the semilunar notch behind, and the white cerebral plate termed Vieussenian valve before; 2d, at its inferior sur¬ face, between the almonds or spinal lobules above, and the upper end (medulla oblongata) of the spinal chord below. The outline of each hemispherical surface of the cerebel¬ lum describes three fourths of a circle; and as the seg¬ ments mutually meet towards the mesial plane, the mode of union varies according to the figure of the objects to which they are adapted. 1st, The hemispherical border, ap¬ proaching the anterior part of the organ, is suddenly in¬ terrupted where the cerebellic peduncles (crura cerebelli) are connected with the protuberance ; and, pursuing a retrograde direction on each side towards the mesial plane, forms a re-entrant curvature or notch—the semilunar—Semilunar corresponding to the lower pair of the bigeminous bodies. llotch- 2d, The hemispherical borders, approaching the posterior part of the cerebellum, proceed, near the mesial plane, by an acute circular turn, almost straight backwards, and form, at the posterior edge of the organ, a deep rect¬ angular notch, H, not unlike the figure of the ancient Purse-like lyre, named the perpendicular fissure of Malacarne, or notch. the purse-like fissure of Reil, and containing the cerebellic vertical portion of the hard membrane (falx cerebelli). Between these two boundaries the cerebellic plates, of which the hemispheres consist, are united in the middle by an interlacement, named suture (raphe), of the cere¬ bellum. A large hollow between the hemispheres, ex¬ tending backwards from the semilunar to the purse-like fissure, is the small valley (vallecula) of Haller. ANATOMY. Special Each hemispherical surface consists of five lobes; 1. Anatomy. t]ie anterior-upper or quadrilateral; 2. the posterior- upper; 3. the posterior-lower; 4. the slender, rarely ex- obes;1C ceeding three lines in breadth ; 5. the two-bellied or biventral; and 6. the central lobe. The first two belong to the upper or flat hemispherical surface ; the next three to the lower or convex hemispherical surface; and the sixth, common to the two hemispheres, is situate on the mesial plane of the upper surface, between the anterior end of the middle line (raphe) and the middle or apex of the semilunar fissure. /’he ton- The biventral lobe is pointed, and its margin concave; sihs. and between this margin and the parts of which the valley consists is placed a group of plates, convex and rounded, named the tonsil or tonsils (tonsillce; amygdala; the spinal lobule of Gordon). The flock. In the angular hollow between the biventral lobe and the peduncle (crus) of the small brain, is the flock, a mi¬ nute body, of irregular shape. Each flock consists of six or seven plates (laminae), starting directly from the begin¬ ning of the peduncle, and with the concave margins di¬ rected towards the protuberance. Phepyra- The valley is distinguished into three bodies, (he pyra- nid, uvu- mid, uvula, and nodulus. The first is a group of 20 parallel a, and plates, with a triangular apex, bounded behind by the mdiile. purse-shaped notch, and before by another cluster of plates called the uvula. The uvula, which is anterior, consists of twelve laminated leaves, is six lines long and four broad, and is smaller than the pyramid, and conical, with its base turned to that body. Lastly, anterior to the uvula, and separated from it by a furrow, is the laminar tubercle (tuberculo laminoso) or nodule, consisting of about ten thin transverse plates, the smallest in the row. . 'cntral The second surface of the brain, in situation interior or lurlace. central, may be named the jigurate or symmetrical. In¬ stead of presenting the uniform eminences and hollows which distinguish the convoluted surface, it is moulded into definite shapes, which correspond with each other, as they are situate on opposite sides of the middle plane,— or the parts of which, when situate on this plane, are ex¬ actly symmetrical. The surface formed by these figured objects bounds what are termed the ventricles or cavities of the brain. They cannot justly be termed cavities any more than the hollows between the convolutions, but ought to be viewed as continuations of the exterior or convoluted surface. The central or figurate surface of the brain presents the following objects. The central band, beam, or meso- lobe, a mass of white cerebral matter, uniting both hemi¬ spheres on the mesial plane, with the twainband or vault below ; the hippocampus major on each side; the anterior pyriform eminence or striated body on each side; the posterior pyriform eminence or optic chamber on each side; the semicircular band on each side; the ergot on each side; the conarium on the mesial plane; the bige- minous eminences on the mesial plane; the valve on the mesial plane; and its pillars on each side, entral Ihe commutual or dichotomous region of the convo- iml ; cor-luted surface is terminated below by the upper surface of u^c.1 o- a white band uniting the two hemispheres. This, which vyas named by the ancient anatomists the smooth or po¬ lished body (aufia. nWoubn, corpus laeve), to distinguish it from surfaces formed by a cutting instrument, appears in the form of white fibrous matter, passing transversely be¬ tween the hemispheres, and marked by three longitudinal lines, one on the mesial plane, and one on each side. This is the middle or central band (mesolobe of Chaussier). Near its middle is a bundle of gray lines, which may be traced to the central portion of the hippocampus major. The posterior extremity of this body is rounded, and Special communicates with the chamber named third or middle Anatomy, ventricle. This surface is continued forward, and forms the vault or cieling (fornix, Die Zwillingsbinde, the twain- band, Reil). The names of callous body and vault are used, as if they were denominations of different bodies. If they are still retained, it ought to be stated that they are names applied to opposite surfaces of the same object. The relations of the posterior end of the middle band The trian- are as follow. The handle of a scalpel inserted beneath gular it is found to be in the middle ventricle, with the vaultvault- above, the conarium or pineal body, and four eminences of the upper surface of the protuberance (corpora bige- mina) below, and a part of each optic chamber on each side. The vault or inferior surface of the band has the shape of an isosceles triangle, with the base behind. Be¬ fore it is incurvated downward as it becomes narrow; and the space between the band and it is occupied by a thin double plate of cerebral matter, separating the two ven¬ tricles, and named the diaphanous partition (septum luci- dum). (s, s, s.) The fornix terminates before, in two bodies named anterior pillars. (Fig. 3, f, f.) The posterior end of the middle band penetrates into The hippo- the substance of the hemispheres; but the gray chords campus already noticed, pursuing their lateral course, are imme-ma.ior- diately enveloped in white plates derived from the sides of the vault, and assuming a cylindrical appearance, form, opposite the cerebral limbs, a body with a free Superior rounded surface, which bends in a curvilinear direction lateral laterally and downwards, and is the great hippocampus orco™muni- cylindroid process. (Chaussier.) In observing this cur-catlon' vilinear course, it rests on and corresponds, but without adhesion, to the upper margin of the cerebral limb as it issues from the optic chamber; and the surfaces of both parts, though kept in apposition by vascular'membrane, are free and unadherent. It forms the great cerebral fis¬ sure of Bichat. The hippocampus, therefore, consists of two parts. The first, which is the gray indented band (le corps godronnee, Vicq-d’Azyr), is an inner or central portion, as thick as a large crow-quill, gray in colour, indented at the free edge, adhering to the cerebral substance by its opposite margin, and connected with the upper surface of the cen¬ tral band. The outer or second part, which is a broad thin plate of white cerebral matter folded over the gray indented band, as a map is rolled over a cylinder of wood, known under the name of the tape or fringe of the hippo¬ campus, is connected with the lower surface of the same central band, or the vault (fornix) of the brain. At the inferior region the communication is effected Inferior by the curvilinear hollow. (Fig. 1, s, s.) This presents, ] st, lateral cerebral substance, penetrated by numerous holes of vari-con?rmmi* ous size, named the white perforated substance (lamina p>er-catlon- forata) ; 2dly, the unconvoluted space ; Mly, the long cere¬ bral band termed the optic tract; and, Uhly, the limb of the brain. This body, with that of the opposite side, is covered by a portion of the convoluted surface, the in¬ ner and prominent surface of the medio-inferior or sphe- no-temporal region. The convoluted surface, which covers the anterior end and outer margin of the cerebral limb, when everted, presents the thin white body named the tape or fringe (tcenia) of the hippocampus; and if the portion of con¬ voluted brain next the curvilinear hollow be raised and everted in the same manner, the anterior end of this ob¬ ject, termed the foot (pes hippocampi), comes into view. The fringe of the hippocampus forms, in the natural position of the organ, the outer and lower border of the opening; while the limb of the brain, and the outer 54 ANATOMY. ed emi- Semicircu- lar band. Optic chamlier Special and lower surface of the optic chamber, form its inner Anatomy, border. When the central surface is exposed by removing the central band and the vault and cieling of the ventricles, two pyriform eminences, an anterior and posterior, come into view. The anterior is ash-coloured or gray, inclin¬ ing to wood-brown, with the round convex extremity be¬ fore, and the small end tapering backwards and outwards, so as to inclose the round end of the posterior eminence. The surface is smooth and convex, consisting of a thin co¬ vering of gray cerebral matter. The interior consists of an admixture of white and gray, so as to form alternate streaks,—a circumstance from which these eminences on each side have been named the striated bodies {corpora striata). At their anterior mesial extremity are two round¬ ed vertical bodies of white cerebral matter, descending from the anterior end of the vault. These are the ante¬ rior pillars, which are thus interposed between the inte¬ rior front of the striated bodies. The posterior and internal margin of the striated bo¬ dies is bounded by a gray, hard eminence, about a line broad, stretching with a sinuous or winding direction from its mesial and anterior to its external lateral and posterior margin. This is the semicircular fillet or band {tainia semicircularis, centrum semicirculare geminum). Always firmer than the neighbouring parts, it appears to be the external margin of a gray-coloured stratum or wall of cerebral matter between the anterior and posterior py¬ riform bodies. Connected before and on the outside to the striated body by means of the double semicircular chord {centrum semicirculare geminum, Vieussens), each optic eminence presents four free surfaces—the upper, the inner, the pos¬ terior, and the lower. The upper is gently rounded, convex, and white in colour; its limits are not easily de¬ fined. The outer margin is bounded by the circular band, which even passes anterior to it, so as to form its bound¬ ary in that direction also. Behind, it is less distinctly limited, unless by the appearance of a considerable pro¬ minence, named the posterior tubercle of the optic couch. The inner margin of the upper surface is distinctly mark- gland and e(il)y a small, sharp, gray line, which, beginning insensibly pedunc es. at tke anterior part of the body, becomes more distinct as it extends backwards, and ultimately bends towards the median plane. There it unites with a similar elevated line of the opposite optic eminence; and to the point of union is attached a small conical body with a minute point, of a gray colour, and of a shape like that of the pine-apple. This is the pineal gland {glandula pinealis, conarium); and the minute linear eminences which form the inner edge of the upper optic surface have been named peduncles of the pineal gland. The inner surface of the optic couch or chamber pre¬ sents the small portion of soft cerebral matter {commissura mollis) which unites it to the similar surface of the oppo¬ site body; and the intermediate space between the inner surfaces of these bodies on each side constitutes the third or middle ventricle {ventriculus tertius). Its posterior edge, however, is terminated by the cerebral limb of that side; and the lower edge meets that of the opposite one, and is connected to it by a portion of brain which forms the lower part of the middle ventricle, and corresponds on the outside to the bridge of Tarin {pons Tarini). Geniculate The posterior surface of the optic chamber is convex tubercles, and continuous with the unconvoluted space. Its most con¬ vex part presents two oblong roundish eminences, sepa¬ rated by a linear depression, which may be traced down¬ wards with an outward curvature, and forwards about five or six lines, in a broad white band, crossing two fluted masses mutually converging behind at an angle. These Pineal Soft com¬ missure and third ventricle. eminences are the geniculate bodies {corpus geniculatum Special externum et internum), the outer the largest of the two Anatomy, (fig. 1, g, g); the white bands are the optic tracts or ori-^^^^ gins of the optic nerve, issuing from the geniculate tu¬ bercles (o, t); and the fluted converging masses are the limbs of the brain {crura cerebri). On the inner or mesial side of the geniculate bodies, Bigemi. and separated only by a linear furrow, are the bigemi- nous emi, nous eminences, four orbicular elevations, two above and11601'63, two below; two on each side of the mesial plane, with an intermediate cruciform furrow. By the ancients, who ex¬ amined chiefly brute animals, the superior and larger pair were named nates (y'hovroi), the inferior testes {dibu/Mi). These eminences occupy the upper surface of the protu¬ berance, and partly that of the limbs of the brain; and while the eminences are situate between the posterior ends of the optic chambers above, the limbs appear to issue from the centre of these chambers below, and the linear furrow marks the point of junction. These bigeminal eminences, however, though occupy-Cerebral ing the superior surface of the protuberance, adhere not valve, everywhere to its substance. (Fig. 3.) The mesial furrow is formed on the upper surface of a thin plate of white cere¬ bral matter, which extends from the level of the pineal peduncles above, to the upper margin of the cerebellum below, like a veil, and is named the cerebral valve {valvula Vieussenii). The lower surface of this is free for about two or three lines broad; and, though applied to a similar surface on the mesial line of the upper region of the protu¬ berance, does not adhere, but forms a canal with the third ventricle above and the fourth below, named the aque¬ duct of Sylvius {iter a tertio ad quartum ventriculum) (i). While the outer halves, therefore, of the eminences ad¬ here to the matter of the protuberance, the inner are at¬ tached to that of the valve, (n, t.) The lower or cerebellic margin of the valve is free, and Pillars of overhangs as it were the fourth or cerebellic ventricle, the valve. On each side, however, is a longitudinal rounded body of white matter, which passes from the lower pair of bigemi- nous eminences {testes) to the cerebellum. These are named the pillars of the valve {columnce valvulce Vieus¬ senii, processus a cerebello ad testes). The fourth or pathe¬ tic nerve {trochlearis) rises partly from the valve, partly from its lateral pillars, and is seen issuing on the sides of the protuberance not larger than a thread. The lower surface of the optic chambers presents with¬ in the convoluted space the limbs of the brain {crura cerebri), two fluted semicylindrical masses, converging backwards, and inclosing by their junction a triangular space, with the apex behind—the intercrural hollow. The inner margin of the limbs presents the origin of the third or oculo-muscular nerves {ocido-motorii) ; about half an inch anterior on the intercrural hollow are the lenticular or pisiform bodies {tubera, v. corpora candicantia), two he¬ mispherical tubercles of white matter; and immediately anterior is the hypophysis or pituitary gland, a broad quad¬ rilateral reddish-gray prominence, with the anterior mar¬ gin rounded, the posterior concave, inclosed before and on the sides by the converging optic tracts and commissure. (p-) . . . . The limbs are obliquely crossed at their outer anterior end by the broad part of the optic tracts as they descend from the geniculate bodies. Their posterior convergent extremities are lost in the substance of the annular pro¬ tuberance {pons Varolii, nodus cerebri), a convex rounded white body, with transverse fasciculi separated by linear furrows, (n.) Connected before with the crura or limbs, from which it is separated by transverse sinuous furrows, it is connected on the sides with the cerebellum by short semicylindrical stalks or peduncles {crura cerebelli), and ANATOMY. 55 lead of yramidal adies. Special behind with the beginning of the spinal chord (medulla Anatomy, oblongata). It is marked on the middle by a longitudinal furrow, in which is placed the basilar artery, the united trunk of the vertebrals. Its convexity corresponds to the concavity of the basilar groove of the occipital bone, on which it rests. This eminence may be regarded as the general central point of the cerebral nervous system, with which all the other parts are connected,—with the cere¬ bral hemispheres by the crura cerebri, with the cerebellic hemispheres by the crura cerebelli, with the upper in¬ ternal part of the optic chambers by the bigeminous emi¬ nences, and with the spinal chord by the medulla oblon¬ gata. From its anterior lateral margin the tergeminal or fifth nerve arises ; from the posterior furrow the abducent or sixth nerve ; and from the upper anterior margin of the cerebellic peduncle the eighth or lateral facial. Continuous with and behind the protuberance is the be- ie chord. ginning or bulb of the spinal chord, a part distinguished on the ground of an obsolete hypothesis by the name of me- didla oblongata. Thick and prominent, its surface is mould¬ ed into six oblong-ovoidal eminences, three on each side of the mesial plane ; the pyriform or pyramidal eminences before, the restiform bodies behind, and the olivary emi¬ nences on each side. The pyriform eminences (corpora pyramidalia) are two oblong-oval bodies, broad above, tapering below, sepa¬ rated by a mesial line, and bounded laterally by a furrow separating them from the olivary bodies, occupying the anterior-inferior part of the bulb of the chord, and rest¬ ing on the lower third of the basilar groove. The mesial line terminates above in the foramen caecum of the poste¬ rior furrow of the protuberance, (p.) The olivary (corpora ovata), placed on the outside of the pyramidal bodies, occupying partly the front, partly the side of the bulb, give it a lateral and transverse pro¬ jection. In the intermediate furrow are the initial fila¬ ments of the hypoglossal or middle lingual nerve ; and in the external furrow and sides those of the glosso-pharyn- geal and pneurnogastric nerves, (o, o.) estiform The posterior-upper part of the medulla oblongata con- . s an(1 sists of two longitudinal cylindrical bodies, stretching between the cerebellic peduncles above and the spinal chord below. These are the chordal processes of Ridley, the restiform or rope-like processes of Morgagni, the py¬ ramidal bodies of Haller, Malacarne, and Red, and the posterior pyramidal bodies of Ruysch, Prochaska, and Soemmering. Above, where they are connected with the cerebellic peduncles, they are separated by a triangular space with the apex downward, but below by a deep fur¬ row, the calamus scriptorius of the ancients, at the bottom of which, when separated, may be observed white chords proceeding from the process of one side, plaited with those of the other. These decussating fibres, which are confined entirely to the mesial margin of the restiform processes, are believed to establish a crossing connection between the right and left sides of the peduncles and the protuberance. The intermediate cavity is named the fourth ventricle. From the inner surface of the restiform process issue several of the initial filaments of the seventh or auditory nerve. The spinal chord or funicular brain is a cylindrical livary odies. eir oove. lie spinal lord. body occupying the interior of the vertebral canal, from the margin of the occipital hole to the first lumbar verte¬ bra; large and round on the cervical region, broad on the dorsal, and terminating in a brush-like expansion, deno¬ minated the cauda equina. On its dorsal surface may be seen a slightly depressed line continued from the middle furrow of the restiform bodies, but becoming faint and indistinct in the region of the back. I he central or figurate surface is smooth, polished, and possesses a degree of closeness of texture which pre¬ vents it from being readily abraded. These qualities are ascribed by Reil to a thin pellicle, which he terms epithe- lia. Though there is no proof of the existence of the covering, the term may be used to designate the smooth surface of the organ. Special Anatomy. Of the central surface not only does every division mu¬ tually communicate, but the central surface of the con¬ voluted communicates with that of the laminated part of the organ. The lateral divisions, named ventricles, com¬ municate directly with each other below the vault, the surface of which lies over the thalami; both communicate with the third ventricle, which by the Sylvian aqueduct communicates with the fourth; and the posterior part of the lateral ventricle communicates with the digital cavity and inferior recess. The central surface is covered by a vascular membrane (plexus choroides), continued from the pia mater of the convoluted surface. Between the two surfaces now described is placed the proper matter of the brain, white and brown, which in dif¬ ferent regions of the organ is differently arranged. The convoluted surface consists of a stratum of gray Structure, cerebral matter, arranged in the granular form. When indurated by immersion in alcohol or dilute nitric acid, it breaks with a small conchoidal fracture, occasionally un¬ even, and with an uneven granular surface, void of lustre* and without fibrous arrangement. The only part of the convoluted surface presenting the latter appearance is the unciform band uniting the anterior and posterior lobes. (Fig. 5, v.) Within the convoluted surface is contained a large quan¬ tity of white matter, surrounding the figurate surface and its divisions. The section of this, usually named the oval centre of Vieussenius (centrum ovale), shows merely the extent which this occupies in the upper part of the brain, but communicates no information on the intimate struc¬ ture of the organ. In intimate organization the brain may be distinguish¬ ed into four parts; ls£, the brain, containing the striated nucleus; 2d, the cerebellum, containing the moriform body; 3c?, the head or bulb of the chord, containing the moriform body; and, kth, the annular protuberance as a central point of the whole. The white fibrous matter of the central band, passing into the hemispheres on each side, diverges like the rods of a fan or the rays of a luminous body, and forms an ar¬ rangement denominated by Reil the radiating crown, and which may be regarded as the exterior investment of the striated nucleus, which constitutes the internal substance of the striated bodies and optic chambers. (Fig. 5, c.) The arrangement of white and gray matter in this part is so peculiar, that within the limits of this sketch it is im¬ possible to convey a distinct idea of it. It may be stat¬ ed in general that the fibrous matter of the limbs ex¬ tends from the protuberance through the substance of the thalamus and part of the striated body; and while in this manner it maintains a connection between the protuberance and the brain above, by means of the ce¬ rebellic peduncles on the sides, and the head of the chord below, it communicates with the cerebellum and spinal chord behind and below. The moriform bodies (corpora dentata, corpora ciliata, corpora rhomboidea), which consist of white matter inclosed in a brown capsule, and the cerebellic and olivary eminences, are analogous to the striated nucleus of the brain ; and the three may be regarded as the respective centres of each. The annular protuberance, consisting internally of transverse fibres closely interwoven with longitudinal ones, is the general or common centre of the three. 56 A N A 1 Special The substance of the funicular or vertebral portion con- Anatomy. sists almost entirely of white fibrous matter, extending longitudinally from the cranial to the sacral extremity, but bending off laterally at the origins of the spinal nerves in the form of arches. Blood-ves- The brain is supplied with blood by the internal ea¬ sels. rotid arteries and the two vertebral arteries, derived from the subclavian. The former, entering the cra¬ nium by the carotic canals, sends a posterior commu¬ nicating branch, inosculating with the principal division of the basilar, and an anterior communicating, which joins the vessel of the opposite side. By these communi¬ cations, the branches of the basilar artery behind, and the carotids before, form an arterial hexagon round the sella Turcica, from which arise two anterior vessels (anteriores cerebri), distributed to the central band, and two lateral {mediae) or Sylvian arteries, distributed to the perforated spot, the Sylvian fissure and striated nucleus. The verte¬ bral, entering by the occipital hole, send branches to the head of the spinal chord, and uniting to form the basilar, supply the protuberance and cerebellum ; then divaricating into posterior cerebral, finally inosculate with the internal carotid to form the arterial hexagon as mentioned. The blood is returned by triangular canals named sinuses, of which there are the superior longitudinal, the inferior longitudinal, the cerebellic {torcular Herophili), the lateral, the circular, the superior petrous, the inferior petrous, and the cavernous. The four latter pairs are small sinuses opening into the lateral, where it emerges from the cranium by the temporo-occipital fissure {foramen lace- rum in base cranii posterius). § 2. THE CEREBRAL INVESTMENTS OR MEMBRANES. The brain is said to be surrounded by three membra¬ nous envelopes, the hard membrane {meninx dura, dura mater), the web-like membrane {tunica arachnoidea), and the soft or thin membrane {meninx tenuis, pia mater). To this arrangement, which has been adopted by almost all writers, there is perhaps no great objection. But it simplifies the subject, without misrepresenting, to refer them to two only ; one of which, the hard membrane {meninx dura, ffxXjjgjj, dura mater), is common to the brain with the inner surface of the scull; the other, the thin membrane {meninx tenuis, priviyi* Xsxrrj, pia ma¬ ter), is proper to the brain only. They may be distin¬ guished, therefore, by the terms common membrane of the brain and proper membrane of the brain. The arachnoid, again, is a pellucid web common to the cerebral mem¬ branes. The dura The first of these, the common or hard cerebral mem- maier. brane {meninx dura, dura mater), presents two surfaces, an outer or cranial and an inner or cerebral. The outer surface is irregular, filamentous, and vascular, and the substance of which it consists is distinctly fibrous. The fibres, however, do not follow any uniform direction, but are interwoven irregularly. Maceration causes this mem¬ brane to swell and become separated into fibrous threads. It is liberally supplied with blood-vessels, by which it is connected to the inner surface of the scull. No nerves or absorbents have been discovered in it. This outer or cra¬ nial surface of the dura mater is of the nature of perios¬ teum. Its vessels may be traced into the inner table; it contributes to the formation of the cranial bones in the foetus, and their nutrition during life. The inner or cerebral surface of this membrane is smooth, polished, and shining; and, when examined in water, it appears to be formed by a very thin, transpa¬ rent membrane, through which the cranial or outer sur¬ face and the fibrous structure of the hard membrane may ' O M Y. be recognised. This pellucid inner membrane,, generally Special termed the inner lamina, is the exterior division of the arachnoid membrane. The dura mater is an extensive membrane, lining Vertebral not only the interior surface of the scull, but, in a modi-sheath, fied form, that of the whole vertebral column. The inner surface of each vertebra has a proper periosteum conti¬ nuous with the periosteum of the outer surface; and from this issues a quantity of filamentous tissue, which penetrates directly a membranous canal, evidently of fibrous structure {theca vertebralis), tough and firm, but more delicate than the cranial dura mater. The dura mater in its course forms sundry prolongations; for in¬ stance, the large crescentic one named Xhefalx, the hori¬ zontal one termed tentorium, and the small crescentic one named jfa/x minor or cerebelli. The thin, soft, or immediate and proper cerebral mem-The pia brane {pia mater, meninx tenuis) presents in like manner mater, two surfaces, a smooth or cranial, which is exterior, and a filamentous or cerebral, which is interior and central. The outer or smooth surface of the thin membrane {pia mater) has a glistening appearance, and is formed by a very thin transparent membrane, exactly similar to that which forms the cerebral surface of the dura mater. This surface, named in the ordinary works the web-like membrane {tunica arachnoidea), is believed to be a sepa¬ rate membrane from the pia mater ; but that which forms the inner or cerebral surface of the dura mater has a claim equally strong to this distinction. The inner or cerebral surface of the proper membrane is filamentous, flocculent, and sends out many angular fila¬ mentous processes, which, by numerous minute arteries and veins, communicate with the convoluted surface of the brain. These processes {tomenta) correspond to the fur¬ rows of the convoluted surface in which they are lodged. In detaching the membrane from this part of the brain, numerous vessels are drawn out of its substance ; and when the membrane is injected these vessels may be seen dis¬ tinctly filled, and communicating with the gray matter of the convoluted surface. The veins of this membrane may be traced to the sinuses. Neither nerves nor absorbents have yet been recognised in it. Bichat considers it to contain much cellular tissue, which, however, is denied by Gordon, who could not recognise it. The difference, how¬ ever, consists merely in name. The pia mater, indeed, possesses no cellular tissue like the subcutaneous, the submucous, or the subserous. If, however, a portion of the arachnoid be peeled from it by careful management of the forceps and blowpipe, there is found a quantity of loose filamentous matter uniting this tissue to the fine web of the former. The existence of this tissue between the pia mater and arachnoid is further demonstrated by the phenomena of serous infiltration. The pia mater, or proper membrane of the brain, consists DistnLu- of two parts, an outer, covering the convoluted surface of tion and the brain, and an inner or central, entering the cavities£ura formed by the inner, central, or figurate surface, and spread over this surface in the form of what has been termed the vascular or choroid web {plexus choroides; tela choroidea). The continuity of the pia mater or exterior division of the proper cerebral membrane, with the choroid plexus or interior division, may be demonstrated in the following manner First, The pia mater may be traced behind and below the posterior extremity of the middle band {iia nXr.ouhtg, corpus callosum, der balken), where it is continu¬ ous with the transverse web called velum interpositum, and which may be regarded as the first part of the central division. Secondly, From the situation of the velum in¬ terpositum, it may be traced forwards on both sides of the ANATOMY. 57 Special mesial plane into the lateral ventricles, spread over the Anatomy, surface of the optic thalamus and striated eminence in the form of the vascular web called choroid plexus, the right half of which communicates with the left by means of a similar slip of vascular membrane lying beneath the vault ( fornix), and behind the anterior pillars of that body at the spot termed foramen Monroianum. Thirdly, It may be traced over the geniculate bodies and thalami into the pos¬ terior-inferior cornu, or sinuosity of the lateral ventricle, where it covers the great hippocampus. Fourthly, It may be traced at the angle between the cerebellum and medulla, ob¬ longata, or what is named the bottom of the fourth ven¬ tricle, where it forms a very minute choroid plexus, seldom noticed by anatomists, but not less distinct, and which may be traced up the fourth ventricle to be connected with the velum interpositum in the middle ventricle, and with the lateral portions of the hippocampus on each side. Each of the divisions of the choroid plexus now enumerated may be shown to be mutually connected, and to form parts of one general membrane, which again constitutes the inner or central division of the membrane of which \hepia mater forms the exterior. Each division of the choroid plexus, in like manner, is connected, by means of minute blood¬ vessels, to the portion of the figurate cerebral surface on which it rests; and it appears to sustain vessels as the jria mater does to the convoluted surface. In clear water the choroid plexus may be spread out, like the pia mater, in the shape of a thin semitransparent web, one surface of which is smooth, the other somewhat flocculent, and the substance of which is traversed by nu¬ merous minute vessels. The transparent web, which forms the basis of this membrane, is filamento-vascular; and its smooth free surface, a continuation of the arachnoid mem¬ brane, is smooth, polished, and thin, like silver paper. The arachnoid membrane is common to the dura mater, pia, mater, and choroid plexus. It covers the inner surface of the first membrane, to which it communicates its shin¬ ing polished appearance, though the want of subjacent filamentous tissue causes it to adhere so firmly, that it cannot be readily demonstrated. After covering the free surface of the pia mater, it follows the course of that membrane into the central surface of the brain, and covers the upper or unadherent surface of the several divisions of the choroid plexus. For the demonstration of this fact we must be permitted to refer to Dr Craigie’s Elements of General Anatomy (chap, xxiii. sect. 1), where the reader will find proofs, which the limits of this sketch do not allow us to adduce here. From these it results that the arachnoid membrane pos¬ sesses in arrangement and distribution a great resem¬ blance to the serous membranes. It differs, nevertheless, in its extreme tenuity, in the closeness with which it ad¬ heres to the collateral tissues, and in its slight disposition to albuminous exudation. It appears to contain in its structure less filamentous tissue than the pure serous membranes. The brain is developed from the branches of the internal carotid and vertebral arteries ramified through the vascu¬ lar membrane {pia mater). Formation commences in two orders of vessels mutually directed to each other,—those of the convoluted surface {pia mater), and those of the cen¬ tral {plexus choroides). The central substance of each part is first deposited; and from these points deposition and moulding proceed to the two circumferences of the organ. Ihe surfaces are therefore formed last; and the vessels gradually shrink as the process approaches to completion. SECT. II. the DISTRIBUTED CHORDS ; THE NERVES. 1 he nerves may be distinguished into classes according to the parts of the brain with which their cerebral ends VOL. hi. are connected. On this principle they may be arranged in the following order. The brain, The limbs, Protuberance or its parts, Head of the chord. Spinal chord, i Olfactory, 1st pair. I Optic, 2d pair. Oculo-muscular, 3d pair. 'Trochlear {nervuspatheticus), 4th pair. Trifacial, 5th pair, ■ Abducent, Auditory, _ Lateral-facial, ' Glosso-pharyngeal, Pneumogastric, Accessory, Hypoglossal, 1 Sub-occipital. 7 Cervical nerves. 12 Dorsal. 5 Lumbar. | Ophthalmic branch. '! Superior maxillary. (Inferior maxillary, fith pair. 7th pair (portio moUis). 8th pair (portio dura). 9th pair. 10th pair {nervus vagus). 11th pair. 12th pair. Special Anatomy. The spinal nerves are derived from anterior and poste¬ rior roots separated by the ligamentum denticulatum, a fibrous notched ligament, covered by arachnoid membrane. According to the researches of Charles Bell and Magendie, the anterior roots furnish motive filaments, and the poste¬ rior sensitive. The central connections of most of these nerves have been already mentioned; and their distribut¬ ed connections have been, and will continue to be, inci¬ dentally noticed under the heads of the several organs. It is requisite, however, to notice shortly the relations and general distribution of several nervous chords which per¬ form an important part in the functions of the animal body. These are the pneumogastric, the phrenic, and the great sympathetic or intercostal nerves. The pneumogastric or nervus vagus, the 8th pair of the Pneumo- old nomenclature, the 10th in correct enumeration of the gastric cerebral nerves, rising by various filaments from the fur-nerve- row between the olivary bodies and the restiform, and from the posterior upper surface of the latter, emerges from the cranium with the jugular vein by the temporo- occipital hole. Here, closely united by filamentous tissue to the hypoglossal, spinal, and glosso-pharyngeal, it de¬ scends before the rectus anticus and longus colli on the out¬ side of the carotid artery, though in the sheath with it, and before the subclavian artery on the right side, on the left before the carotid, enters the chest, where it enlarges in size considerably. (Plate XXXI. v, v.) In the chest it passes behind the bronchi in the posterior fold of the pleura, and is closely connected to the oesophagus in the shape of a thin cord. Both trunks, on reaching the car¬ diac end of this tube, pass with it through the diaphrag¬ matic aperture, and are distributed to the stomach. In this course the pneumogastric nerve is divided into five orders of filaments. 1. In the neck it gives branches to the pharynx, and, communicating with the glosso-pharyngeal, forms the pha¬ ryngeal plexus, and furnishes a superior laryngeal branch, an external laryngeal, and an internal laryngeal, the latter chiefly to the intrinsic muscles of the larynx. 2. In the chest it sends off branches, which, communi¬ cating with those of the superior cervical ganglion, are distributed to the heart. 3. In the chest also it gives off the inferior laryngeal or recurrent nerve (r), which on the right side winding round the subclavian, on the left the arch of the aorta, re¬ ascends in the lateral furrow between the windpipe and oesophagus, and giving off cardiac, pulmonary, oesophageal, thyroid, and tracheal filaments, is finally distributed to the intrinsic muscles of the laryngeal cartilages. These multi¬ plied connections tend to associate the motions of the glottis with the lungs, and to maintain a general consent between the pharynx, larynx, oesophagus, trachea, lungs, and heart. H 58 Special Anatomy. ANATOMY. The phre¬ nic nerve. The great sympathe¬ tic or splanchnic 4. The pneumogastric trunk forms with the filaments of the inferior cervical ganglion the anterior pulmonary plex¬ us, and alone it forms the posterior pulmonary plexus, which sends filaments to the lower part of the windpipe, the bronchi, the pulmonary artery and veins, and the oeso¬ phagus. 5. After passing the diaphragmatic aperture, the right pneumogastric trunk forms at the cardiac orifice of the stomach a plexus, from which filaments proceed to the pylorus, the gastro-hepatic artery, the right cceliac gang¬ lion, the duodenum, the pancreas, the gall-bladder, and the liver, where it communicates freely with the coeliac ganglions. The pneumogastric of the left side is distri¬ buted chiefly to the pylorus and its arteries, and commu¬ nicates freely with those of the right. The phrenic or diaphragmatic nerve, connected above with filaments of the pneumogastric, hypoglossal, second and third cervical nerves, and some branches of the bra¬ chial plexus, and occasionally with those of the great sym¬ pathetic, descends on the anterior and lateral part of the neck, between the rectus anticus and scalenus anticus, and enters the chest between the subclavian artery and vein. The right passes down on the surface of the right lung, beneath the pleura (f, which open into the left. The di- the°car(liacrection in which the blood flows on both sides is from the diambs. venous apertures into the auricles, thence to the ventricles, and thence to the respective arteries. The venous blood, on reaching the auricle, distends it, and impels its muscles to contraction ; and the cavity thus diminished expels the blood in the only direction in which it can proceed,—by the aurico-ventricular aperture into the ventricle. This chamber being distended, its muscular walls all round, especially at the base, contract and diminish its cavity, when the blood, extruded, quits the ventricle in the only direction in which it can, viz. by the aperture of the pul¬ monary artery. The blood from the pulmonary veins fol¬ lows the same course in the chambers of the left side. The blood of the ventricles is prevented from returning into the auricles partly by the tricuspid and mitral valves, but chiefly by the annular contraction of the auriculo-ven- tricular apertures, which are drawn from the margins to¬ wards the septum; while the latter is shortened, and the apex is made to approach the base. ihe distribution of the branches of the aorta may understood fiom the following tabular view. S o r C3 □ u tu •*-> X W Superior thyroid. Pharyngeal. Lingual. External maxillary. Occipital. Post-auricular. Temporal. .Internal maxillary. 15^ f Ophthalmic. £ '-g I Posterior communicating, •g £ 1 Anterior cerebral. ° [Middle cerebral. 'Vertebral. Inferior thyroid. Suprascapular. Transverse cervical. Ascending cervical. Deep cervical. Internal mammary. . Superior intercostal. § 2. THE ARTERIES AND VEINS. Connected with each ventricle is a large tube, in which the blood flows from the trunk to the branches. The pulmonary artery, the first of these, divaricates into a right and left branch, subdivided and distributed respec¬ tively to the right and left lung. The aorta, which is the second, is the large artery which distributes the blood after aeration in the lungs to the system at large. The aorta, rising from the left ventricle, after giving off the cardiac arteries, makes an antero-posterior incurva¬ tion with the convexity upwards, denominated the arch or curvature (arcus aortce). (Plate XXXI. a, a.) From the upper side of this arch arise three large vessels, the innominata or subclavio-carotid, the common trunk of the right subclavian and carotid arteries (i), the left carotid (i), and the left subclavian. The aortic trunk, after this curvature, proceeds downward on the left margin of the dorsal vertebrae, giving oesophageal, bronchial, and superior intercostal arteries, thymic, pericardial, and in¬ ferior intercostal arteries successively. From the level of this arch to the parabolic opening of the diaphragm at the tenth dorsal vertebra, it is distinguished by the name of thoracic aorta; and below this, to the fourth lumbar verte¬ bra, it is the abdominal aorta. At its transit through the parabolic aperture it sends off the diaphragmatic arteries. The vessels issuing from the abdominal aorta may be dis¬ tinguished into two orders, those which issue from its sides in pairs, and those which issue from its anterior surface sing¬ ly only. The former consists of the capsular, distributed to the renal capsules; the renal or emulgent, to the kidneys; the spermatic, to the testes; and the lumbar, to the lumbar muscles, and that region generally. The latter are three in number only, the cceliac, superior mesenteric, and inferior mesenteric. Opposite the fifth lumbar vertebra, or the fibro- cartilage uniting the fourth and fifth, the aorta terminates by divaricating into two large lateral trunks, the common or primary iliacs (iliacce communes'); while from its middle be¬ hind proceeds a small azygos artery, distinguished as the sacro-median, along the median line of the sacrum. In this course the aorta is placed in the posterior angle of the thoracic and abdominal serous membranes, and, inclosed by the anterior vertebral filamentous tissue, sends from its posterior surface numerous arteries to the vertebral column and spinal chord. vol. m. -o 3 irj < o. 2 CQ i bJD 1 O 1 £ ^5 Pi External thoracic. Infrascapular. Circumflex humeral. Deep humeral. Anastomotics, or Articulars. Radial i*ecurrent. Superficial volar. Dorso-radial of the thumb. Dorso-radial of the fore finger. Annular—deep arch. . f Ulnar recurrents. c3 1 Interosseal, p j Nutritious. L Volar or palmar—superficial arch. Ileo-lumbar. Sacral-lateral. Obturator. Gluteal. Ischiatic. Internal pudic. Umbilical. Vesical. Middle hemorrhoidal. Uterine. Vaginal. (Inguinal portion. f Epigastric. (Circumflex iliac. Deep f Circumflex femoral, femoral. (Perforating. Superior articular. Inferior articular. Internal inferior circumflex. External inferior circumflex. Anterior 1 ^ rr Deep tibial. / Dorsal of the foot-1 plantar T1 , . (Internal plantar. ) arch. tibhal°r i External plantar—superficial . Peroneal. a; Oh 3 c/i arch. i 66 A N A T Special In general the denominations of these arteries indicate Anatomy, the parts to which they are distributed. In the ultimate distribution of the arterial system, however, there is great variety; and it is often impossible to determine the exact origin, course, and distribution of the smaller terminations. The trunks alone are constant in position. In distribution, the following general rules are observed:—ls£, The arterial trunks send small lateral branches to the parts between which they run. 2dly, The majority of individual organs are supplied, not by one proper vessel, but either by one principal artery and two or more subordinate ones, or by several subordinate ones. 3dh/, A trunk, after giving off several lateral branches, may either terminate in one vessel, which is ultimately distributed to the organs to which it is destined; or it may divaricate into several, none of which may be considerable enough in size, or di¬ rect enough in course, to be regarded as the proper termi¬ nal vessel. Thus it is often difficult to determine whether the temporal artery or the internal maxillary is the con¬ tinuation of the external carotid, which of the palmo-digital arteries is the continuation of the radial, whether the an¬ terior or the posterior tibial artery is the continuation of the popliteal, and whether the dorsal of the foot is the termination of the former, bthly, In the terminal vessels, where inosculation is frequent, it is impossible to deter¬ mine whether an artery arises from one trunk or another. Thus in the arterial arches of the hand and foot, in which the digital vessels issue from the convexity of the arch, it is impossible to say whether these arteries arise from the radial or the ulnar in the one case, or the anterior or the posterior tibial in the other. The arteries are accompanied by veins, which in gene¬ ral correspond, for the purpose of conveying the residual blood, after distribution, to the right chambers of the heart, to be transmitted by the pulmonary artery to the lungs for renovation. The veins of the head, chest, and superior extremities, open into the superior cava ; those of the lower part of the trunk, the pelvis and pelvic ex¬ tremities, terminate in the inferior cava ; the veins of the stomach, intestinal canal, spleen, and pancreas, terminate in the portal vein; and the regredient hepatic veins are united in one vessel, which terminates in the upper end of the inferior cava. SECT. II. THE ORGANS OF AERATING CIRCULATION, OR RESPIRATION. The lungs are two soft, spongy, vascular bodies, con¬ tained in the cavity of the chest, one on each side, and imitating in shape the internal figure of that region. Each lung, resembling somewhat a cone, with one side truncated, and the base obliquely cut, is distinguished into a convex external surface, corresponding to the concave internal one of the thorax ; a flat inner or mesial surface, corresponding to the mediastinum ; a rounded obtuse apex, corresponding to that of the demithorax; and a concave base directed obliquely from the mesial plane to the hypochondres, cor¬ responding to the convex surface of the diaphragm. Each lung is distinguished into lobes (lobi) separated by fissures (fncisurce). The right, which is the largest, consists in general of three lobes, the superior, middle, and lower; the left of two only, an upper and lower. The mesial margin of the left is distinguished from that of the right by a sinuous notch, indicating the situation of the heart (fovea cardiacd). The intimate structure of these bodies, which has been the subject of much research, depends on the nature of the tubes which are distributed to them, and of which chiefly they consist. These are the bronchial or breath- tubes (bronchi), the continuations of the windpipe, and the branches of the pulmonary artery and veins. O M Y. The windpipe (trachea) is a cylindrical tube, about four Special or five inches long, extending from the cricoid cartilage, to Anatomy, which it is attached by a fibro-mucous membi ane behind the sternum, to the level of the third dorsal vertebra, or the fibro-cartilage between it and the second. (Plate XXXI. t.) It consists of from 17 to 18 or 20 cartilaginous rings (annuli), truncated behind, united by a fibrous membrane without, continuous, but particularly firm in the interannu- lar spaces, and along the whole posterior part of the canal. These fibres are white, firm, longitudinal, and closely set. Within is the mucous membrane, continued from the la¬ rynx to the bronchi, resting on filamentous tissue, in which arc embedded the mucous follicles. By many, muscular fibres have been represented to exist between the rings ; according to Soemmering transversely and longitudinally; and Reisseissen has recently maintained their reality at the posterior part of the tube. Their fibrous disposition is undeniable, but their muscular character may be doubted. The windpipe, covered before by the thyroid gland, and corresponding to the sigmoid pit of the sternum, is at¬ tached to the oesophagus behind by filamentous tissue. Opposite the third dorsal vertebra the trachea is bifur¬ cated into two tubes named air-tubes (bronchi), which are directed obliquely to each lung with a mutual intermediate angle of about 35°. The right is about one fourth larger and one fifth longer than the left. Both are cylindrical, but divaricate at their lower end, where they sink into the substanceof the lungs, into several smaller tubes(irorac/wa), which again ramify and subdivide into tubes still smaller, and successively. The interbronchial angle is occupied by lymphatic glands, which are also arranged round the tubes. The bronchi consist of cartilaginous rings, complete above, but parted into three annular segments between the middle and lower ends, united by whitish fibrous tissue, longitudinal externally, transverse within, and lined by mucous folliculated membrane. As they advance into the substance of the lungs, and are still more minutely divid¬ ed, the cartilages diminish in size and firmness, and their place is supplied by fibrous tissue of transverse circular fibres, which at length also disappear, and mucous mem¬ brane alone is left. These transverse annular fibres have been supposed by Haller, Soemmering, and recently Reisseissen, to be mus¬ cular. It is not improbable that they are so ; but no posi¬ tive proof of this fact has yet been adduced, and they ap¬ pear rather to belong to the elastic fibrous system. The larger bronchial tubes are accompanied each by an artery derived from the aorta or the subclavian, and fol¬ lowing their ramifications into the pulmonic substance. The blood conveyed by these vessels is returned either to the vena azygos or the superior cava. The pulmonic or final divisions of the bronchial tubes terminate in blind sacs covered by mucous membrane, and communicate with each other, forming an appearance of intersecting compartments, which have been distinguish¬ ed by the name of air-cells (cellulce aerece), or pulmonic vesicles (vesiculce pulmonis). They are represented as polygonal and irregular, and about one eighth or one tenth part of aline in diameter. (Haller and Soemmering.) On the whole, these air-cells appear to be merely the termi¬ nations of the bronchial tubes mutually communicating, lined by a very delicate mucous membrane. The pulmonary artery, ramified and subdivided to a great degree of minuteness, communicates most freely with a number of vessels, which may be traced into trunks terminating in the pulmonary veins. This capil¬ lary system, enveloped in filamentous tissue, is distributed beneath the mucous membrane of the terminal bronchial tubes or communicating cells. The exterior surface of this filamentous tissue is covered by the pleura. From ANATOMY. Special these facts it results that the lung consists of cartilaginous Anatomy. an(j fibrous tubes mutually intersecting, and the capillary communications of the pulmonary artery and veins, inve- loped in filamentous tissue, lined on one side by mucous membrane, covered on the other by transparent serous membranes. The air-cells, lined by mucous membrane, have no communication with those of the filamentous tissue, as some have absurdly imagined. Except this fila¬ mentous tissue, the lung has no proper substance ox paren¬ chyma ; and its structure is entirely filamento-vascular. In the capillary vessels of the pulmonary artery and veins, the venous or modena blood, exposed to the in¬ fluence of the inspired air through the thin bronchial membrane, parts with its dark, and gradually acquires a bright red tint. This may be styled the aerating or ar- terializing capillary system. The lung, however, receives other vessels, the bron- chials, by which its mucous aerating membrane and sub¬ mucous tissue are nourished. Entering with the bron¬ chial tubes between the folds of their pleura, these ves¬ sels are subdivided as they proceed, and at length form a minute network on the attached surface of the bronchial mucous membrane. The lung derives its nerves from the eighth pair chiefly, and a few filaments from the great sympathetic. The lung is well supplied with lymphatics, both superficial and deep. SECT. III.—THE ORGANS OF SECRETORY CIRCULATION, OR SECRETION. Of the organs of secretory circulation, several, as the lacrymal gland, the salivary glands, the liver, and pan¬ creas, have been already considered ; and others, for ex¬ ample the testes, will fall under subsequent heads. This, however, is the proper place to notice the organs of the urinary secretion, which consist of two glands, the kidneys, and two excretory ducts, the ureters, terminating in a common receptacle, the bladder. The kidneys (renes) are two glandular bodies situate in the posterior or lumbar part of the abdominal region, one on each side of the lumbar vertebras, behind the pe¬ ritoneum, and before the psoas muscle and part of the diaphragm, with the quadratus lumborum behind and la¬ terally, and enveloped in a thick layer of adipose tissue. The right kidney is below the liver, above the caecum, behind part of the duodenum, colon, and the right extre¬ mity of the pancreas. The left is bounded above by the spleen, by the transverse arch of the colon before, and it has the sigmoid flexure below. The right kidney is about two inches from the outer margin of the vena cava, and the left at about the same distance from the outer margin of the aorta. The situation of the right kidney is generally lower than that of the left, so that part of its lower extremity is in the iliac fossa, while the lower extremity of the left is quite above the margin of the ilium. Resembling in general shape the large French bean, named from it, each kidney may be described as an ob¬ long body, convex externally and at both ends, and with a sinuosity at its inner margin, named the renal fissure {fovea rents), in which the vessels and excretory duct are contained. Each kidney is between four and five inches long, and two broad; and the weight of each varies from three to four ounces. The anterior surface, correspond¬ ing but not attached to the outer surface of the peri¬ toneum, it convex, but becomes hollow at the inner mar¬ gin, where it terminates in the renal fissure. The pos¬ terior surface, which is less convex, is separated from the internal aponeurosis of the transverse abdominal muscle, 67 The kid¬ neys. the diaphragm, and the psoas magnus, by a thick layer Special of adipose tissue. Anatomy^ The kidney consists of glandular structure, invested by a firm membrane, somewhat fibrous in appearance. In the glandular structure the anatomist recognises the Structure, most distinct example of this form of tissue. It consists of two parts, a granular external, and a tubular internal. The former, which occupies the exterior of the kidney, is a homogeneous substance, of a yellow fawn colour, and con¬ sists of minute spherical or spheroidal granules {granula), aggregated together by filamentous tissue, and forming at their exterior calycoid or cup-like cavities, in which the round fundi of the tubular conoids are lodged. In these the capillary vessels of the kidney are ramified with great minuteness. The tubular part consists of very minute capillary tubes {tubuli uriniferi, tubuli Belliniani), varying in length, united by filamentous tissue, and arranged in parallel juxtaposition, so as to form conoids with globu¬ lar bases, which are lodged in the cup-like cavities of the granular portion, and rounded apices directed to the renal fissure. The number of these tubular cones varies from 10 or 12 to 18 or 20. Their apices form an equal num¬ ber of nipple-like processes {papillce), covered by a thin membrane almost transparent, in which are numerous minute holes, apertures of the tubes of which the cones are composed. These apertures, however, are much less numerous than the tubes, several of which are united in one common orifice. The renal papillae thus constituted project into a series of conical cavities, formed within of the papillary membrane, without of fibrous strata and fila¬ mentous tissue. These cavities, which from their shape are denominated funnels {infundibula, calyces), uniting into three or four larger ones, terminate in a considerable membranous sac named the basin {pelvis) of the kidney. These two parts of the kidney are distinguished not only in structure but in colour and consistence. While the granular part is fawn-coloured, and somewhat soft and flabby, the tubular is pink-red, fleshy and firm; and the boundary line is distinct. The tubular cones are separated from each other by partitions, which appear to be fila¬ mentous tissue. There is no doubt that the granular is the secreting part of the gland; and the tubes are merely conduits of the urine, which indeed may be expressed from their apertures. It is important, however, to determine the mode in which the two portions communicate. The as¬ sertion of Ferrein and Eysenhardt, that the tubes are blind canals, is inaccurate in this respect, that the terminal tubes evidently communicate with others in the interior of the cones, which again are immediately connected with the granular part. It further appears, that in the granu¬ lar part there are very minute white tortuous canals, which appear to communicate with the straight tubes of the cones. All beyond this is entirely conjectural. The kidney, therefore, cannot be said to possess paren¬ chyma or proper substance. The idle distinctions into cortical and medullary ought to be rejected as remnants of an exploded theory. The kidneys are supplied with blood from the aorta byBlooa-ves- the renal arteries. Issuing at right angles from the late-sels. ral regions of the abdominal aorta, below the superior me¬ senteries, these vessels pass directly into the fissure at its superior and anterior part, the left behind, the right occa¬ sionally before the renal vein, but crossing its direction. The calibre of these vessels is considerable, about three lines at least; and they have been estimated to convey the sixth part of the blood of the abdominal aorta. The left artery is about one inch long, the right is the whole breadth of the vertebral column longer. In the renal fissure each artery divaricates into three or four consider- 68 ANATOMY. Special able branches, which enter the kidney a little above the Anatomy, attachment of the basin (pelvis). These vessels are again subdivided into an anterior series before, and a posterior cluster behind the infundibula, which they accompany to the papilla. Dividing more minutely, they form anasto¬ motic arches, from the convexity of which proceed minute vessels, radiating into the granular substance of the gland. These vessels are distributed principally to the granular matter at its calycoid surfaces, in which the tubular cones are lodged. The veins are arranged exactly in the same manner, and connected with the renal trunk, much as the arterial branches are connected with it. The kidney is supplied with nerves, accompanying the arteries, derived from a plexus inclosing the renal trunk, and which is originally formed from filaments of the solar of the great sympathetic. The basin The pelvis consists externally of a prolongation of the or pelvis, renal investment, a proper middle membrane, white, opaque, and fibrous, and an inner lining, which, though thin and semitransparent, presents the character of mu¬ cous membrane. The upper extremity of each kidney is covered by the renal capsule, a substance of no peculiar structure, and the nature of which is unknown. The ure- The basin forms the common termination of the renal ters. funnels, and the commencement of the ureter. This is a membranous tube, of the diameter of a moderate-sized quill, passing between the renal basin, behind the perito¬ neum, to the posterior and inferior part of the bladder, in which the lower extremity opens. Each ureter is inclin¬ ed to the mesial plane below. The right ureter is on the outside, and neaidy parallel with the inferior cavity. Both cross the psoas at an acute angle, and below the common iliac arteries and veins. In the pelvis they cross the vas deferens in the male, and on reaching the bladder pass ob¬ liquely, from eight lines to an inch, through its coats, and open in the posterior margin of the lower fundus of that organ. These tubes consist of fibrous membrane, lined by mu¬ cous and covered by filamentous tissue. It contains no muscular fibres, notwithstanding the assertions of some. The ureters are supplied with blood derived from the renals, occasionally from the lumbars and spermatics, but more especially from the aorta by two ureteric arteries. The uri- The urinary bladder is a muscular membranous bag, nary blad- spherical above and cubo-spherical below, placed on the lower region of the pelvis, behind the pubal symphysis, and before the rectum in the male, and the uterus in the female. From the peculiarity of its figure and relations, it is distinguished into a superior/Mficfes, spheroidal, direct¬ ed to the abdominal cavity; an inferior fundus, cubo-sphe- roidal, between the ureters and urethral opening; a neck (cervix), pyriform at the latter point; an anterior surface, corresponding to the posterior of the pubal symphysis; a posterior, corresponding to the rectum in the male and the uterus in the female; and lateral regions, corresponding to the ilio-ischial inner surface, and those of the obturator inter mis and levator ani. In females generally the transverse extent of the blad¬ der is greater than in the male, and in females after child¬ bearing than in the virgin. In infancy its superior fundus is pointed and conical rather than globular,—a peculiarity derived from its fcetal shape, which is pointed, with the urachus, a ligamentous chord proceeding to the navel, at¬ tached. Structure. The bladder consists of a muscular coat, covered above, behind, and laterally by peritoneum, and lined by mucous membrane. The peritoneal covering is continued from the anterior surface of the rectum, and the lateral regions of the pelvis Sjiecial over the posterior and lateral and part of the superior sur-Anatomy, faces of the bladder, all of which are iree ; while the infe¬ rior yjmrfKs, the neck, and the anterior, are covered by fila¬ mentous tissue, connecting the organ to the neighbouring parts. This filamentous tissue is abundant, especially below. The muscular coat, always distinct, varies in thickness in different individuals. In females, so far as we have ob¬ served, it is rather thicker than in males. The fibres run in all directions, but are strong at the superior surface, where some anatomists have arbitrarily distinguished them by the name of detrusor urince. I here are no fleshy pillars, mentioned by some, in the healthy state. The neck is surrounded by a thick range of circular fibres, which has been denominated the sphincter of the bladder. The mucous membrane, without villi or epidermis, is ex¬ tended over the whole inner surface of the organ, and is continuous behind with that of the ureters, and before with that of the urethra. The space inclosed between these three orifices is named the vesical triaw fie (trigonus vesica)-, and a minute duplicature of the mucous membrane at the urethral orifice is denominated the vesica uvula. The bladder is supplied with blood chiefly from the posterior iliac or hypogastric trunk, by means of the com¬ mon pudic, the obturator, the ischiatic, and the hemor¬ rhoidal. Of these, one vesical artery proceeds from the hemorrhoidal; another often comes off directly from the hypogastric as an inferior vesical; and in some instances they issue from the umbilical. The vesical nerves are partly from the sympathetic, partly from the sacral. The capacity of the bladder varies in different indivi¬ duals. In the female it is generally more capacious than in the male. In the healthy state it may contain a pound of urine, without extreme distension ; and it is often ca¬ pable of containing two, three, or four pounds. Its situa¬ tion varies at different periods of life, and in different de¬ grees of distension. In the foetus and infant, when the pelvis is small, the bladder is contained in the abdomen. In the adult in the ordinary state it is within the limits of the pelvis; but when much distended, its superior fundus, rising above the pubis, is in the abdomen. During preg¬ nancy, also, it is thrust forwards and upwards by the gravid womb. Urine, the fluid secreted by the kidneys, is particularly distinguished by containing, with various saline substances, urea, an animal principle containing 46 per cent, of azote. As the saline ingredients also abound in principles con¬ taining this element, it may be inferred that the chief pur¬ pose of the kidneys is to remove from the system a con¬ siderable proportion of nitrogen, which would either be injurious by its presence, or disturb the due proportion of the other elements. The urethra, which terminates the urinary apparatus, is nevertheless common to it with the reproductive organs. The male urethra especially is more connected with the reproductive than the secretory organs. In the female, in whom alone this canal is proper to the latter, it is a short muco-membranous tube, terminating in a papillated ori¬ fice in the superior anterior wall of the vagina. PART III. ANATOMY OF THE ORGANS PERTAINING TO THE REPRO¬ DUCTIVE FUNCTIONS. These organs, by the possession of which the indivi¬ duals of the human race are distinguished into two sexes, male and female, consist in the former of impregnating, and in the latter of the impregnable organs. The former may be again distinguished into preparing and transmitting ANATOMY. Special organs ; and the latter into receiving and ootrophic organs, Anatomy. 0r those which nourish the product of generation. CHAP. I.—THE MALE OR IMPREGNATING ORGANS. The male organs consist of two glandular organs, named testicles with excretory ducts, for secreting the impreg¬ nating fluid, and an organ for transmitting it to those of the female. The testicles (testes) are two ovoidal bodies contained on each side of the mesial plane in a cutaneo-cellular sac named the scrotum, attached to the anterior inferior part of the pubal symphysis. I'he scro- The scrotum consists of skin with very thin corion, rest- um. jng 0n loose filamentous tissue, which forms on the mesial plane a thick wall, separating the right half of the scrotal bag from the left. On the median line is a superficial groove, named suture (raphe), at which the corion and filamentous tissue, elsewhere loose, are united into a solid and firm substance. Most of the old anatomists mention a muscular layer known by the name of dartos, and to which they ascribe the contraction of the scrotum on ex¬ posure to cold ; but the existence of this muscular layer is not supported by inspection. The scrotal skin is well supplied with arteries, and especially veins connected with those of the epigastric, external iliac, femoral, obtu¬ rator, and external pudic, the branches of which anasto¬ mose freely. The nerves are from the lumbar, obturator, and crural. The scrotal filamentous tissue incloses on each side a thin membranous sac of a pyriform shape, with the base below, and tapering to a neck above. Adherent on the outside to the filamentous substance, this membranous sac is free and smooth within, except at the neck, where it embraces a part distinguished by the name of spermatic 'he vagi- chord. This, which is the sheath-like or vaginal coat al coat, (tunica vaginalis), is distinguished into two parts, an in¬ ferior pyriform, forming a cavity for the testicle, and a su¬ perior cylindrical, covering the spermatic chord, and ad¬ hering to it. This membrane is said to be fibrous exter¬ nally ; but it appears to be merely condensed filamentous tissue. Within it is evidently a transparent serous mem¬ brane, both in qualities and distribution. It is continued from the adherent part of the chord downward, and over Ithe testicle. 'he albu- Within the cavity of the former are contained the tes- incous tides, both suspended by the spermatic chord, with the epididymis behind. Their substance is inclosed in a firm, opaque, white, fibrous investment, covered by a thin trans¬ parent membrane, reflected from the vaginal coat. The former is the tunica albuginea, or proper tissue of the gland ; the latter is the vaginal coat of the testicle (tunica vaginalis testis). 'he tes- The testicle consists of minute irregular-shaped gra- nules, of a white or gray-white colour, soft, closely com¬ pacted, and with numerous capillaries distributed through them. More minutely examined, these are found to be capillary tubes of extraordinary length, folded on them¬ selves, and contorted so as to occupy a small space, and when unfolded extending, according to some anatomists, 'he semi- 16 feet, according to others to 25 or even 100 ells. These iferous Jong tortuous tubes, which are named the seminiferous J es‘ (ductus seminiferi), are estimated at about 300 in num¬ ber. . Ihey communicate by one extremity with the blood¬ vessels and lymphatics of the testicle, and by the other, after several unite into one common duct, terminate in about 20 larger tubes, denominated egredient ducts (vasa efferentia), which, united in a cluster by means of fila¬ mentous tissue, and invested by part of the tunica albugi¬ nea form at the upper part of the gland a whitish cylin- dncal body, about six lines long and two broad, distin- Special guished by the name of the process of Highmore (corpus Anatomy. Highmori). flhese efferent vessels unite and form a single tube of gieat length, which, folded on itself by innumer- ^ie iy°’ able turns, connected by filamentous tissue, and invested ri*Si? by tunica albuginea, constitutes the epididymis, attached Thf emiT’ by its head to the testicle, and by an incurvated extremity didvmis. named tail, continuous with the common excretory duct (vas deferens). I he latter is a long fibro-cartilaginous tube, ascending The vas upwards from the tail of the epididymis, and making deferens or part of the spermatic chord, with which it enters theseminal abdomen at the inguinal aperture. At the inner margin excret017 of this it separates from the chord, and descends into a]ong the lower surface of the cavernous body, from 1 he spongy jts anterior extremity, where it constitutes the glam, to ,oc^’ the angular bifurcation of the cavernous body, where it is expanded into a substance denominated the bulb of the urethra. The spongy body is invested on the side and below by integuments only. Their Both these parts, but especially the cavernous body, structure. consist of numerous minute arteries, communicating di¬ rectly with elongated and dilatable veins, and constitute the best example of erectile arrangement in the body. The injection of these vessels constitutes the erection of the penis, and induces the contraction of the urethra necessary to expel the seminal Huid. The two extremities of the spongy body, the glam before and the bulb behind, form the limits of the erectile tissue round the urethra. The anterior extremity is covered by loose skin, which forms the foreskin (praeputium), and, in the shape of a thin semi- mucous corion, provided with epidermis, is continued over the glans, from which it passes insensibly into the mucous membrane of the urethra. With the penis several muscular organs are connected. The ischio-cavernosus and tramversus perincei on each side connect the cavernous body to the ischium; and the bulbo-cavernosus connects it to the bulb of the urethra. Mr Houston of Dublin has lately discovered a packet of muscular fibres situate between the pubal arch and the penis on each side, which, by compressing the dorsal vein, may, he imagines, contribute to erect the organ. The cavernous and spongy bodies are supplied with blood from the terminal end of the internal pudic artery, by means of two vessels, the cavernous and the dorsal. The bulb receives branches from the transverse perineal artery. The pros- The prostate gland is a body cordiform or flat conoidal late gland. in shape, with the base behind and the apex before, cor¬ responding to the vesical end of the urethra, situate behind the pubal symphysis before, and below the neck of the bladder, in the angle between it and the rectum, and be¬ tween the levator ani of each side. It is distinguished into three lobes,—two lateral, united on the mesial plane,—and a small cellulo-vascular slip in the angle between them, towards the base. In structure it is composed chiefly of minute arteries and veins rami¬ fied in a firm, fleshy, filamentous tissue, amidst which are placed follicles with minute ducts, which terminate in larger tubes, varying in number from seven to twelve, the apertures of which are on the sides and the surface of the urethra. These follicles secrete a viscid liquor, the use of which is unknown. From the fact, however, that, when the prostate gland is diseased or injured, the sexual ap¬ petite is languid or extinguished, it may be inferred that the prostate is essential to the generative functions in the male. It is analogous to the uterus in the female. Cowper’s With the prostate may be mentioned the accessory y.aiuis. glands of Cowper, two small bodies, oblong-round, placed on each side of the urethra, before the prostate. They appear to be mucous follicles on the large scale. The ure- The urethra is a membranous canal, extending from thra. tile neck of the bladder in the pelvis to the extremity of the glans, where it terminates on the surface by an aper¬ ture (orificium urethra), consisting of two lateral seg¬ ments. Its length and width vary in the erect and unerected state of the penis. In the latter it is about seven or eight inches long, and its calibre is about three lines, but admitting of distension beyond this. Accord¬ ing to the parts with which it is connected, it is distin¬ guished into four different portions; ls£, the prostatic, about one inch ; 2d, the membranous, from one to one inch and a half; 2>d, the bulbous, scarcely one inch; and, the spongy portion, occupying the anterior part of the Special canal, inclosed by the spongy body. Anatomy. The surface of the urethra is a mucous membrane sup- plied with follicles, and moulded into blind sacs named lacuna, which appear to contain mucous ducts. Its capacity varies in different parts. Wide at the middle of the prostate, it is contracted in the membranous part, which is indeed the narrowest of the canal; it enlarges again in the bulb; and from this it preserves the same diameter to immediately behind the glans, where it forms a dilatation distinguished by the name of the navicular (fossa navicularis). The apertures in this canal have been already mentioned to be, besides that of the bladder, one ejaculatory on each side of the veru-montanum, from seven to ten excretory apertures from the prostatic ducts, and one aperture from each accessory gland. The mu¬ cous membrane of the membranous and spongy portions presents longitudinal folds, which appear to be connected with the occasional distensions of the tube for the expul¬ sion of the urine. The urethra, straight in direction on the mesial plane, is incurvated within the pelvis from behind forwards, so that its concave incurvation incloses the pubal arch, while its convexity is turned to the perinaeum. The pen¬ dulous state of the penis, when unerected, causes it to ac¬ quire another incurvation without the pelvis, with the con¬ vexity directed upward. These curvatures are consider¬ ably exaggerated in engravings. The first round the arch of the pubis is much less angular than it is delineated. CHAP. II.—-THE FEMALE OR OOTROPIIIC ORGANS. The female generative organs consist of the ovaries, the uterine or Fallopian tubes, the womb, and the vagina. These organs are contained in the pelvis. From the time of Steno, anatomists have given the name The ova- of ovaries or eggbeds (ovaria) to two ovoidal bodies, about nes. the size of a pigeon’s egg, placed one on each side of the womb in the pelvis, in a duplicature of peritoneum termed the broad ligament (ligamentum latum) of the uterus. Con¬ vex and free on their anterior and posterior surfaces, and tapering towards each extremity, their lower margin is straight or slightly concave, with a vascular sinuosity. The external extremity is contiguous to a round solid chord (ligamentum teres), forming the anterior margin of the broad ligament, and proceeding from the womb to the internal orifice of the inguinal canal and the pubal extre¬ mity of the ligament of Poupart, and by which the uterus is retained in the pelvis. Each ovary weighs about one drachm and a half. Covered externally by peritoneum, stretched over a Ovarian fibrous membrane of some firmness, the ovaries consist of vesicles 01 a pulpy brownish-gray substance, very vascular, in which S61™3- are embedded minute bodies of vesicular appearance and oval shape, varying in number from 15 to 20. These bo¬ dies, which, from the time of De Graaf at least, have been regarded as ova or embryal atoms or germs (ova Graaji- ana, ovarii vesicula), consist of a thin membrane contain¬ ing a viscid, reddish, or yellow fluid. The ovary is supplied with blood from arteries analo¬ gous to the spermatic of the male. Previous to puberty the ovaries are smooth in surface and entire. After this period, both in females who have had children, and even in virgins, they are marked on the surface by minute depressions, which have been denomi¬ nated cicatrices, and which are believed to be the conse¬ quence of minute breaches of the ovarian tunics, occasion¬ ed by the escape of the vesicles from the surface of the ovary. There is no proof that these cicatrices are the invariable result of sexual intercourse. Small before pu¬ berty, at that period they acquire considerable size, and ANATOMY. Special retain them till the age of 45 or 48, after which they .natcmy. shrivel and shrink to a very small size. The Fallopian or uterine tubes are the excretory ducts of the ovaries. They are cylindrical tubes about four or five inches long, contained in the anterior fold of the su- vine, after sending branches to the vagina and neiehbo perior margin of the broad ligament, between the round ing parts, ascend along the margins of the organ and ligament and the ovary, and connected by their lower ex- ^ ^ —i... 71 the spermatic, partly from the hypogastric. The former, Special a ter passing between the folds of the broad ligaments, Anatomy. and giving branches to the tubes, enter the uterine stance by its lateral regions. The second, named the ute- long, broad at its drachms to 14 ounce. tremity with the superior angles of the womb. Their supe rior extremity, which is loose, is surrounded by a fringed or laciniated slip of peritoneum, in the centre of which is seen the upper or peritoneal aperture (orificium superius), larger than the calibre of the canal, which admits a hog’s bristle, but contracts at the lower or uterine extremity (orijicium uterinum), which is situate in the upper angle of the inner surface of the womb. Covered by serous membrane externally, lined by thin mucous membrane with follicular glands, the Fallopian tubes consist of fibrous tissue interposed between these two. Below, however, at their junction with the womb, they seem to partake of the structure of that body. |he womb. The womb (uterus, matrix) is a hollow organ with thick walls, shaped like a conoid, flattened before and behind, situate on the mesial plane in the pelvic cavity, between the bladder before and the rectum behind. Small before puberty, at that period it is about inches widest part, and weighs from 7 It is distinguished into the fundus, body (corpus), and neck (cervix); the first free, directed upwards; the second also free, between the bladder and rectum; and the third connected within and below to the vagina. At each side of the fundus is a corner or angular part, which communicates with the uterine ex¬ tremity of the Fallopian tube. The neck of the womb may be distinguished into the external or peritoneal, and the internal or mucous neck, which terminates in an ellip¬ tical opening, with rounded, thick, firm margins, not unlike the mouth of the tench, and named therefore os tincce, as well as os uteri. These lips become rough and irregu¬ lar in women after child-bearing, in consequence of the distension during parturition. The cavity of the womb is small compared with the volume of the organ, in consequence of the thickness of its containing walls. It is triangular in shape, with the base at the fundus, and the apex at the neck. The su¬ perior angles are small recesses, in which the uterine ex¬ tremity of the Fallopian tube of each side opens. The cavity is much contracted at the neck, forming a short cylindrical canal, the lower aperture of which is the os uteri, communicating with the vagina. Covered externally by peritoneum, the womb consists of a peculiar thick, firm, whitish substance, lined by mucous membrane. This intermediate matter, though neither red nor distinctly fibrous, has been very general¬ ly regarded as muscular. Its contractile powers during parturition it is impossible to doubt. But while it is dif¬ ficult to reconcile this phenomenon with the absence of muscular tissue, it must be allowed that it is much more easy to maintain than demonstrate the unequivocal ap¬ pearance of muscular fibres. On this topic the reader may consult a paper by Mr Charles Bell, in the 4th volume of the Medico-Chirurgical Transactions ; and an elaborate account of the different ranges of muscular fibres in the ute¬ rus, by Madame Boivin, an eminent Parisian accoucheuse, in her Memorial de l'Art des Accouchemens, Paris, 1824. Ihe uterine mucous membrane is thin, but reddish- gray, villous, and marked by numerous pores, the aper¬ tures of blood-vessels, most probably those which secrete the menstrual fluid. At the neck it is provided with muciparous glands, which are the seat of several of the forms of leucorrhoea. Ihe blood-vessels of the uterus are derived partly from •ucture. distributed to its fundus. The uterine veins correspond to the arteries in course and connections. In the walls of the organ they form large sinuses, very distinct after parturition. The uterine lymphatics are connected with those of the pelvis and hypogastric region. The nerves, which are numerous, proceed from the lower extremity of the great sympathetic, from the renal plexus, the spermatics, the last lumbar nerves, and the sacral. The womb is the proper ootrophic organ, to the inner surface of which the ovum is attached by a vascular body denominated the placenta or after-birth. The vagina is a membranous vascular tube, situate on The va. the mesial plane, behind the pubal arch and urethra, andgina- befine the rectum, and extending from the neck of the womb in the pelvic cavity to the external outlet {vulva), where it is continuous with the surface. Not exactly cylindrical, but flattened before and behind, its length is about four inches, its breadth one, but very distensible. It is generally distinguished into the upper vaginal recess {vagince fundus), inclosing the neck of the womb behind the os tincce, the lower vagina {vagina propria), and the vaginal opening {vulva). The vagina consists of mucous membrane surround¬ ed by filamentous tissue, a vascular network, and some muscular fibres. The mucous membrane, which is red below, gray above, and not unfrequently marbled, soft and spongy, is disposed in numerous large transverse and semicircular folds {rugce) on the anterior and poste¬ rior surfaces. In the recesses of these folds are numerous pores, evidently the source of the mucous viscid secretion which is so abundant on this membrane, during sexual excitation, at the period of parturition, and morbidly in gonorrhoea in the female. On the lateral regions it pre¬ sents pyramidal eminences (papillce). The mucous membrane is connected by filamentous tissue to another, which in the vicinity of the uterus is compact, firm, and elastic, and below, towards the ori¬ fice, is thinner, and contains a network of numerous com¬ municating vessels, in which the blood is occasionally ac¬ cumulated in the manner of erection. The lower extre¬ mity is inclosed laterally by some muscular fibres {con¬ strictor vulvce), which are believed to have the effect of contracting the vagina voluntarily, and by which, when continued, as they occasionally are, to the base of the labia magna, women, according to Soemmering, may move these parts. The vaginal membrane is provided with lympha¬ tics connected with those of the pelvis. The nerves, which are numerous, and some of which appear to termi¬ nate in the pyramidal eminences, are derived partly from the sacral, partly from the crural trunks. The vagina terminates in the vulva, an opening formed within by the clitoris before, the hymen behind, and the nymphce or labia parva on each side; externally by the mons veneris before, the frenum and navicular fossa be¬ hind, and the labia magna on each side. The clitoris is a small, oblong, conical process, consist¬ ing of erectile vessels, covered by mucous membrane, attached to the lower margin of the pubal symphysis. The hymen is a crescentic fold of mucous membrane, surround¬ ing the sides and posterior part of the vagina. The small lips or nymphce {labia parva) are two crescentic bodies, consisting chiefly of erectile vessels, contained within a duplicature of semimucous membrane. With these the inner surface of the labia is continuous; and they consist 72 ANATOMY. Special chiefly of filamentous tissue, placed between semimucous Anatomy, membrane and skin. Connected with the female ootrophic organs are the l he female or mammce. breast. The femaie 0f t]ie human species has only two breasts ; and their position on the anterior and superior part ot the thorax, on each side of the mesial plane, is a character its external surface to the inner of the chorion, and in- Special closing a watery fluid, variable in quantity, in which the Anatomy, foetus, suspended by the umbilical chord, floats. The umbilical chord (funis umbihcahs) consists of, ls£, The umbi. one vein and two arteries, inclosed in—2d, a soft, semifluid, heal chord, gelatinous substance, named from Wharton gelatina Whar- toniana; 3d, the urachus, a ligamentous chord proceed- the thorax, on each side ot the mesial plane, is a cnaracier , —, — ^ hhdder • and Uh the which, with those of .the h—e apparatus, indicates umbilical sheath (vagina umbilicalis). In the eaily period of uterine life, it also contains part of the intestinal canal, the vesicula umbilicalis either partly or wholly, and the omphalo-mesenteric vessels. Of these parts the umbilical veins and arteries, by their connection with the placenta, are the most important. The others our limits allow us The gland is of a flat, rounded figure, and consists of m^ely tomdjeate or orbicular, thick, cake-shaped The pi,, lobes of white pulpy substance, separated . from each 0filament0.,Leak;, attached tocent,P the inner surface of the womb, and a smooth membranous to which the umbilical chord is fixed. It consists of distinctly the erect biped attitude Of a hemispherical or conical shape, the female breast consists of a glandular organ, named the mammary, sur¬ rounded by adipose tissue, and covered by integuments. It is distinguished into the breast (mamma), the nipple (papilla, mammilla), and a coloured ring of skin (areola) other by filamentous tissue, and which may be resolved into granules or acini about the size of millet seeds, which again are composed of minute oblong vesicles disposed in a radiating manner. From the granules or acini proceed minute tubes named the lactiferous (ductus lactiferi, tubuli galactophori), which uniting into larger tubes, varying in number from 20 to 30, terminate in the centre of the mammary gland, behind the areola in conical dilated sacs (sinus), varying from one or two to three lines in diame¬ ter. These galactophorous ducts, which are larger than in any other gland, are formed of mucous membrane, which extends into the sinuosities, and is at the nipple identified with the skin. Several of the lactiferous tubes are said to originate from the adipose tissue of the breast; but this seems merely to indicate that they communicate with the vessels of this substance. The lactiferous tubes are indistinct before puberty, small in the virgin, and in general in the sterile, and during the intervals of preg¬ nancy, and large only at the close of that period, and du¬ ring the process of suckling. The nipple of the female breast is a flat, conical process, the shape of which is well known, consisting externally of skin, with thin delicate corion and epidermis, internally of mucous membrane, and an intermediate network of dilata¬ ble arteries and veins mutually and freely communicating. These parts are united by filamentous tissue, which varies in quantity at different periods. But from the vessels now mentioned the nipple derives its property of occasional erec¬ tion, especially under the influence of mental emotions. The breast derives its blood from the internal mamma¬ ries, the intercostals, and the thoracics or external mam¬ maries, the branches of which penetrate between the lo¬ bules of the gland. It has lymphatics, though not more abundantly than any other organ. The nerves are chiefly cutaneous. The mammary gland is separated from the pectoral muscle by a thick cushion of adipose substance, on which it rests; and it derives a gentle conical elevation from the subcutaneous adipose tissue. The mammary skin is re¬ markable for the delicacy and softness of the corion. CHAP. III. THE PRODUCT OF GENERATION. The ovum or impregnated germ, the result of the union of the sexes, consists of an embryo or new animal, inclosed in several membranes, and attached to the inner surface of the uterus by a vascular mass. The foetal Of the membranes, one, the decidua (epichorion), be- mem- longs to the uterine surface; the other two, the chorion branes. and amnion, belong to the feetus or embryo. The decidua consists of two parts, an external (decidua vera), and an internal (decidua reflexa) ; both modifications of albumi¬ nous secretion. The chorion, the outer covering of the foetus, is a thin transparent membrane, covered with vil- losities on both surfaces, but especially the external. The amnion is a thin transparent membrane, adhering feebly by one, lobular portions (cotyledones), separable from each other, and each of which receives a small artery derived from the uterine trunks, which are much enlarged during pregnancy. The average weight of the placenta is 1 pound 2 ounces. The placenta, according to Dr Hunter (Anatomical Description of the Human Gravid Uterus, edit, by Dr Baillie, Lond. 1794), consists of two portions ; a fcetal or umbilical, and a maternal or uterine part. The foetal part is composed entirely of ramifications of the umbilical arteries and umbilical vein. Ihese, divid¬ ing with extreme minuteness, are distributed to all parts of the placenta. The branches of the umbilical arteries finally terminate in the umbilical vein, and have no other termination: all thebranches of the umbilical vein arise from the umbilical arteries, and have no other commencement. The maternal part consists of a whitish-coloured sub¬ stance, which is spread over the outer surface of the pla¬ centa in the form of a membrane, and sends off innumer¬ able irregular processes, which pervade its substance as deep as its inner surface. These are everywhere so blended and entangled with the ramifications of the um¬ bilical system, that it is impossible to discover the nature of their union. They are interwoven in such a manner, however, as to leave innumerable small vacuities or cells between them, which communicate freely with each other through the whole mass. The maternal part is full of large and small arteries and veins, none ot which are de¬ rived from the vessels of the foetal part, but all from the arteries and veins of the uterus. All the arteries ai'e serpentine, and much convoluted; the larger, when in¬ jected, are almost of the size of crow-quills; and, after little or no ramification, they terminate abruptly in the cells already described. This is their only termination. The veins have frequent anastomoses, pass in a very slanting direction, and generally appear flattened; some of them are as large as a goose-quill, but many ot them very small; and all arise abruptly from the cells of the placenta. This is their only commencement. The umbilical arteries, which are branches of the hypo-Umbilical gastric, ascend beside the bladder and before the rectum, arteries, approach each other, pass over t\xc fundus of the bladder, and reach the navel with the urachus. There they alter their direction, and are wound round the umbilical vein, which proceeds from the placenta by the same aperture (the navel) by which the arteries escape. These arte¬ ries, which are almost equal in diameter to the hypogas¬ tric or posterior iliac, of which they appear to be the con¬ tinuation, diminish in size after birth, and appear then to be mere branches. Eventually they are obliterated and con¬ verted into solid chords, about inch from their origin. The umbilical vein, which is larger than both arteries Umbita taken together, is the common trunk of the veins of the veul- ANATOMY. Jecial placenta, from which it proceeds through the umbilical tomy. opening or navel, in the folds of the falciform ligament, to the umbilical fossa of the liver, where it divides into two branches, one large, proceeding to the venaportce and liver, another small, into the vena cava, known by the name of venous duct or canal {ductus venosus). The umbilical vein is distributed chiefly to the left lobe of the liver, comical The structure of the foetus differs in many respects liari- fr0ni that of the adult; and these differences depend on °f the t]ie gtage which the process of developement has attained. 9' As it is impossible to trace the history of this interesting process within the limits of this sketch, we shall merely specify the principal anatomical peculiarities by which the foetus is distinguished from the full-grown subject. A large vascular body, denominated the thymus gland, is found to occupy the anterior mediastinum. The kid¬ neys are covered by triangular filamento-vascular bodies, named renal capsules, larger than the glands themselves, and supplied with large blood-vessels. The liver is very large, especially its left lobe, and occupies not only the right hypochondriac and epigastric, but the left hypo¬ chondriac region. The lungs are compact and of a deep red colour, and sink in water; and the bronchial tubes are collapsed and void of air. In the heart the right and left auricle communicate freely by an oval aperture in the septum. The pulmonary*^ artery, rising from the right ventricle, divides, not into two, as in the adult, but into three branches; one on each side, going to each lung, small, and conveying little blood; and one in the middle, proceeding to the aorta, about 9 lines long, named the arterial canal {ductus vel canalis arteri¬ osus). The umbilical vein, proceeding to the liver, is distributed by about 15 or 20 branches to the left lobe of that organ. In the horizontal furrow it divides into two branches, one of which goes to the portal vein, the other, apparently the continuation of the trunk, opens into the vena cava, under the name of venous duct {ductus vel canalis venosus), forming with it an angle acute above, and provided with a valve. The kidneys consist of lobules as numerous as their tubular cones, which indeed these lobules are, separate from each other. The urinary bladder is not within the pelvis, but in the abdominal part of that cavity; and it terminates above in a point, to which a liga¬ mentous process {urachus), connecting it to the navel, is attached. In the male, the testicles are contained in the abdomen, often immediately behind the internal aperture. Lastly, till the seventh month the pupillary aperture is closed by a peculiar membrane. The engravings with which the foregoing article is illus¬ trated have been sufficiently explained by literal or numeral references, in the course of description. We have only to add, that fig. 1 and 2 of Plate XXX., from Soemmerring, a, e intended to show the important parts at the lower surface of the brain ; fig. 3, from the same, the relations of the middie band, vault, and septum; and the other two, from Reil, the internal arrangement of the nucleus. Plate XXXI., from Scarpa, shows the phrenic nerve, and the thoracic part of the pneumogastric and sympathetic, with the cardiac plexus and nerves. 1 late XXXII., from Cruikshank, gives a general view of the arrangement of the lymphatics. " In the foregoing account of the anatomy of the human body, many points have been treated in a manner too short and cursory, considering their importance ; and in the at¬ tempt to restrain it within due limits, the heads of several uiye been only indicated. It was the intention of the author to introduce all the new information in microscopical anatomy, which the researches since the year 1832 had furnished. This VOL. III. 73 lowever, particular circumstances render impracticable. For Special those who wish to study the subject more minutely, besides Anatomy, the works occasionally mentioned, we refer to the following1 general systems and treatises. ° 1. S. Th. Soemmerring De Corporis Humani Fabrica ; Latio donata, ab ipso auctore aucta et emendata. Tom i De Ossibus, Trajecti ad Moenum, 1794. Tom ii De Li- gamentis Ossium, 1794. Tom. iii. De Musculis, Tendini- bus, et Bursts Mucosis, 1796. Tom. iv. De Cerebro et Nereis 1798. Tom. v. De Angiologia, 1800. Tom. vi. De Splanch- nologia, 1801. This work, which is excellent so far as it goes, and is particularly distinguished for clear arrangement, and distinctness, precision, and accuracy of description, is in¬ complete. It wants the anatomical description of the eye, the ear, and the generative organs in the two sexes. The first two defects, however, are ably supplied by the author in his Abbildungen des Menschlichen Auges, fol. Frankfort 1801; and Abbildungen des Menschlichen Hoerorqanes. fob Frank. 1806. Of this work a new and greatly enlarged edition, in which the deficiencies above noticed are ably supplied, was pub¬ lished at Leipsic between 1841 and 1844. See historical sketch. 2. Traite AAnatomie Descriptive ; par Xav. Bichat, Me¬ dian du Grand Hospice d’Humanitie de Paris, Professeur d’Anatomie et de Physiologie. Tome i. a Paris, 1801; tome ii. et iii. 1802 ; tome iv. par M. F. R. Buisson, 1803 ; tome v. par Philib. Jos. Roux, Prof. d’Anatomie, 1803. The death of the author interrupted the publication of this work in the middle of the third volume, the first part of which only is by Bichat; while the sequel of that volume is compiled from the materials left at his death. This constitutes the most accu¬ rate descriptive system yet extant; and the strongest proof of its superiority is, that its descriptive portion has been very closely copied in the work of Colquet. 3. Cours dAnatomie Medicale, ou Siemens de VAnato¬ mie de VHomme, avec des Remarques Physiologiques et Pa- thologtques, et les Resultats de V Observation sur le Siege et la Nature des Maladies, dapres VOuverture des Corps ; par Antoine Portal, Prof, de Med. &c. &c. Paris, 1803, tomes cinq. A complete and accurate work. 4. Handbuch der Menschlichen Anatomie, von J. F. Meckel, Band i. ii. and iii. Halle und Berlin, 1815. This work was translated into French in 1825, by MM. Jourdan and Breschet. 5. Traite d!Anatomie Descriptive, redige d’apres Vordre adopte d la Faculte de Medicine de Paris ; par Hippol. Clo¬ quet, Docteur en Medicine, &c. This is a very good system of descriptive anatomy. In arrangement, M. Cloquet follows that of Bichat; and in description the first volume, and a great part of the second, are copied almost literally from the first, second, and part of the third of that author. It would have been quite as well had this been avowed; for it de¬ prives Bichat of much of his most unquestionable merit, and gives an unfavourable impression of the candour of M. Clo¬ quet. In the sequel of the second, on the vascular system, and the organs of. respiration and digestion, the author has availed himself of the materials of Soemmerring. 6. Elements of the Anatomy of the Human Body in its sound state, ivith occasional remarks on Physiology, Patho- logy, and Surgery, by Alexander Monro, M.D., &c. 2 vols. Edinburgh, 1825. On the subject of General Anatomy, on various details on the anatomical divisions and peculiarities of the Brain, on the minute structure of the Lungs, the Liver, the Kidneys, and other glands, we refer here in general, besides the works men¬ tioned in the close of the historical sketch, to the following treatises. 7. Elements of General and Pathological Anatomy, pre¬ senting a view of the present state of knowledge in these 74 ANATOMY. Coxnpara- branches of science, by David Craigie, M.D., F.R.S.E., Fel- tive lowofthe Royal College of Physicians, Edinburgh, and Hon- Anatomy. orary Consulting Physician to the Royal Infirmary. Second edition, enlarged, revised, and improved. Edinburgh and London, 1848. Philadelphia, 1851. 8vo, pp. 1072. 8. The Cyclopcedia of Anatomy and Physiology. Edited by Robert Bentley Todd, M.D., Professor of Physiology and of General and Morbid Anatomy in King’s College, London. London, vol. i., 1836; vol. ii., 1839; vol. iii., 1847; vol. iv., 1852; large 8vo. 9. Elements of Anatomy, by Jones Quain, M.D. Fifth edi¬ tion, edited by Richard Quain, F.R.S., and William Shar- pey, M.D., F.R.S., Professors of Anatomy and Physiology in University College, London. In two vols. London, 1848. 10. On the Structure of the Lungs. Pesearches on the Mi¬ nute Structure of the Lungs in Man and the Principal Mam- miferom Animals. By M. Le Dr Rossignol. Edinburgh Compara. Medical and Surgical Journal,jo\. Ixxn, p. 88. July 1849. 11. The Human Brain, by Samuel Solly, F.R.S. Lon- v don 1847, 8vo., pp. 628. . . - m ^ 12. Plates of the Brain in Explanation of the Physical Faculties of the Nervous System, by Joseph Swan. Lon¬ don, 1853. 4to. . . 7 tt/. 7 13. Archivfur Anatomic, Physiologic, und W issenschaft- liche Medicin. Herausgegeben von Dr Johannes Muller. Berlin, 1834-1853. On the subject of Chirurgical and Topographical Ana¬ tomy, it would be difficult to refer to a more useful work than the following, , , j 14. Surgical Anatomy, illustrated by lithograph coloured engravincs ; by Joseph Maclise, Surgeon. London, 1849— 1851. Second edition, 1853. (d. C.) COMPARATIVE ANATOMY. PART I. ANATOMY OF THE ORGANS OF RELATION. CHAP. I. COMPARATIVE OSTEOLOGY. Bones ge¬ nerally. Red-Blooded Animals only can be said to possess that assemblage of bones denominated skeleton; and as in these the most constant part is the vertebral column, it furnishes the general character of Vertebrated. The shells of the Mollusca and the Crustacea have been ge¬ nerally regarded as a species of internal skeleton; and in the circumstance of affording mechanical support and external protection, they indeed resemble the skeleton of the Vertebrata. But neither in mode of developement nor in chemical constitution can they be regarded as of the same nature. Hence it is only in the vertebrated classes that it is requisite to study the peculiarities of the skeleton. In general characters the bones of the Mammalia re¬ semble those of the human subject. Like them, they are white, firm, elastic, and incompressible. They consist also of compact and reticular or cancellated tissue. In the lower animals the latter kind of structure is in gene¬ ral coarser and looser than in man; and in the Cetacea especially the cavities are large. In the carnivorous ani¬ mals the compact structure is exceedingly dense, and gives the bone much greater weight than in other animals. In the Cetacea also the acoustic or lithoid portion of the temporal bone is of a marble hardness. The bones of the Mammalia may, like those of man, be distinguished, according to their mechanical form, into long, flat, and short bones. Though the first class in ge¬ neral possess a medullary canal, this cavity is imperfect or wholly wanting in the bones of the Cetacea and Am¬ phibia. The cavities denominated sinuses are much more com¬ pletely developed in several of the Mammalia than in the human skeleton. In the pig these cavities extend into the occipital bone ; in the elephant they not only give the frontal bone extraordinary protuberance, but they extend into the parietal, temporal, and even the occipital bones, and contribute much to augment the volume of the head. In the ox, deer, and sheep, they communicate with the cavity of the horns. The bones of Birds are in general whiter, firmer, and smoother than those of the Mammalia ; and they con¬ sist of a firm, compact substance, which is elastic and hard in the bones of the trunk, and extremely brittle in those of the extremities. With the exception also of some of the thin, flat bones, as the sternum, they consist of thin, compact walls, inclosing large capacious cavities, which contain not marrow, but air, and which communicate by one or more minute holes with the windpipe and lungs. While these cavities, which may be regarded as the most perfect and advanced form of sinuses, diminish consider¬ ably the weight of the whole skeleton, by the density and completely cylindrical shape, they rather augment the strength. In the chick, and at birth, the bones are ho¬ mogeneous and without cavities; afterwards they contain marrow; and eventually this disappears and gives place to air. The bones of the Reptiles are not remarkable in any respect, unless in being void in general of medullary ca¬ vity. The absence of this canal was originally observed by Caldesi, and afterwards by Cuvier, in the tortoise; by Troja in the bones of the frog and toad; and by Carus in those of the turtle. In the crocodile, however, and in several of the lizard family, they are large and distinct. The bones of Reptiles also are less firm than those of Birds and Mammals. The bones of Fishes are remarkable for great softness, flexibility, and elasticity. Those of the lamprey, shark, ray or skate, and sturgeon family, are soft, flexible, sec- tile, of a bluish white colour, translucent, and so elastic that a cutting instrument forced into them is speedily re- truded by the resilient nature of the bony matter, from these characters, the bones of these families have been regarded as cartilaginous, and the fishes themselves have been distinguished by this character. (Pisces cartila- ginei, pisces chondropterygii.) In the other fishes, the bones, though softer than those of Mammals, Birds, and Reptiles, present a greater degree of firmness and so¬ lidity, are whiter and more opaque, and are much less sectile, than those of the cartilaginous division. As in this respect, therefore, they approach the genuine bone of the Mammals, these are distinguished as fishes with osseous skeletons. (Pisces ossei.) The bones of both classes of fishes consist of a large quantity of gelatine, with a small proportion of phosphate ANATOMY. Compara¬ tive Vnatomy. 75 late i:xxiv. s "'hml, ls that not only of man, but of the ourane- live The colour of the bones of fishes, though in general outang, silky monkey {simia marikina\ patas (s vatas) Anatomy whitish gray, is observed to vary in certain genera. In maimon (simin maimon), macaca (simia ajmmolqus), the gar-pike (esox below), for instance, they are green, baboon (s. sphynx), magot (s. mum), mandrill (s maimon) and in the viviparous blenny (blenmus vtvtparm), the pongo (s.pmujo), niacauco (lemur catta), vamnvre ureat sand launce (ammodytes tobianus), and two species of and horse-shoe bat, colugo (galeopithecus) shrew hare labrus (the l. lapina and (eruginosa), they assume a green and rabbit, agouti, flying squirrel, mouse and field rat and colour after boiling. The causes of these varieties in camel and dromedary. The next most frequent number is 13, which is that of the mole, white bear, civet, the cat tribe (felis), the dog, wolf and fox, the didelpfiis tribe, the cavy, guinea pig and paca, the mouse tribe, excluding the two exceptions already mentioned, the long¬ tailed manis, the stag, the antelope genus, the o^at, sheep, and ox, and the dolphin and porpoise. The num¬ ber is 14 in the gibbon, coaita, and weeping monkey, in the colour are unknown. SECT. I.—OSTEOLOGY OF THE MAMMIFEROUS ANIMALS. The skeleton of the Mammalia bears a general resem¬ blance to that of the human subject, in the construction, shape, and disposition of its component pieces. Distin- rsal ftebrae. ,7 i . ~ r ^<„uaiLa, cuju weeping monxey, m the guishea, like that, into head, trunk, and extremities, we howling ape (simia beelzebul), the tarsius, the brown bear recognise the importance of the trunk, and especially of raccoon and coati, the weazel genus, the porcupine, ho£^, the snine, in the different classes of mammiferrms nnl. and giraffe. It is 15 in the lori, hedgehog and tenrec, in the badger, pangolin, and seal. The number is 16 in the glutton, hyena, ant-eater, American lamantin, and mega¬ therium. In the horse, quagga, and dugong, they are 18 ; in the rhinoceros 19 ; in the Indian elephant and tapir 20; and in the Unau or two-toed sloth 23, which, as al¬ ready stated, is the greatest number yet known. In the ape family the dorsal vertebrae resemble those of the human subject, but their spinous processes are long, and erect in the macaca and magot. In the bats, instead of spinous processes, which are wanting, there are the spine, in the different classes of mammiferous ani¬ mals. The spine consists of separate vertebrae, which are con¬ veniently distinguished, as in man, into cervical, dorsal or costal, lumbar, sacral, and coccygeal or caudal. The number of cervical vertebrae is the same in animals with the longest and shortest necks,—in the horse, camel, and giraffe, and in the mole and ant-eater. They are al¬ ways seven. The only exception is observed in the Ai or three-toed sloth (bradypus tridactyld), which has 9 cervical vertebrae (Cuvier); and an apparent exception is presented \ s ' ” rr— x ^ wiicuc wcumxig, mere an in the dolphin and porpoise, in which the first two are con- minute tubercles. The want of these, however, in sun- solidated into one; and in the cachalot or large-headed dry species, leaves the column comparatively smooth be- whale, in which the last six. sometimes the whole cpv£»n llinrl- Tn til^ TAmr\ov /nmorlviimx/Ja 1 whale, in which the last six, sometimes the whole seven, are united or ankylosed. The last six are also united in the ant-eater and manis (Cuvier). Even in this state, however, the traces of the original separation are distinct. In the ape the cervical vertebrae are distinguished from hind. In the proper quadrupeds these processes are larger, straighter, and stronger, as the head is weighty or sup¬ ported on a long neck, in order to give attachment to the strong yellow cervical ligament. This peculiarity is very -r- Hum distinct in the giraffe, camel, ox, rhinoceros, and elephant. those of man chiefly by the spinous processes being stronger In the dolphin they are straight, and smaller than those of and not bifid, and in their bodies being projected more the loins. over each other before, so as to support the head more The lumbar vertebrae vary in number still more, per-I'umbar perfectly. In the Zoophaga the transverse processes of haps, than the cervical and dorsal; and this variety may oc- vertel>r£e. the cervical vertebrae are flattened from behind backwards, casionally be traced to the greater or less distinctness with and those of the atlas are very large, both for supporting which the sacral and coccygeal are distinguished. The the head and giving attachment to the strong muscles smallest number is 2, which is that of the two-toed ant- eater, ornithorhyncus, and American lamantin; and the greatest 9, which is that of the lori. The most frequent number is 7, which is that of the greater part of the monkeys, the macauco, the great bat (noctula), the hedge¬ hog, shrew, raccoon ; the tiger, panther, puma, and cat, in the feline genus; the wolf and fox in the dog; the hare and rabbit; the whole murine genus except the hamster; and in the camel and dromedary. The next number in frequency is 6, which is that of the horse-shoe bat, the colugo (galeo- employed in defence, attacking prey, or bearing it off. For the same purpose the spinous process of the axis is very prominent, while the others are short and directed towards the head. In the mole and shrew the cervical vertebrae, which are void of spinous processes, are simple osseous rings, which move easily on each other, probably to facilitate the frequent motions requisite in these ani¬ mals in burrowing. In the hog the cervical transverse processes are compressed and broad before, so as to ap- a # 7 1 7 ^ I/Aac iiwi oc-oiiuc Uctt, 111C UUiLlgU KUIAICO- pear double. In the elephant the cervical vertebrae have pithecus), the white and brown bear, the coati, the weasel snort Single spinous nrocesses. and thp hndips nrmppti'no- o-cmne klio r„l- .1 ] short single spinous processes, and the bodies projecting over each other as in the ape. In the Ruminants the length of the spinous processes diminishes as the neck is elongated. Thus they are almost wanting in the camel and giraffe, in which the arched neck is much retro-flected; genus, the civet, the lion, among the feline, and the dog among the canine genus, the didelphis and cavy genera, the hamster, the stag, antelope, goat, sheep, ox, horse, and quagga. The gibbon, coaita, Ai, Echidna or Ornithorhyn¬ cus hystrix of English zoologists, six-banded armadillo, i ... . uvu .71 A-iiigxiDu puuiugious, ,siA.-ua,iiueu aimauiiio, and the same peculiarity is recognised in those of the and dugong, have only 3 lumbar vertebrae; the ourang- 10tn’ ,, . , , , . outangj pongo, and howling ape, 4; the vampyre bat 4; the I-rom these facts it results that the length of the neck hyena, armadillo, Unau, and tapir, 4; the jocko, tarsier, C,c n6n S n°^ 0It1 * 10 nurnker’ hot on the longitudinal extent, and common bat, 5; the badger and glutton, the porcupine, ° Tjf C?lvicf vertebrae. beaver, pangolin, long-tailed manis, hog, giraffe, gazelle, j i e f.01^ ’ ^ 'oracic, or costal vertebrae are distinguish- chamois, and seal, all 5 ; and the agouti and flying squir¬ ed by forming the central fixed basis of the ribs; and rel have 8. ^ n?im^)er depends on that of the latter class of bones, In theQuADRUMANA and Zoophaga generally the outer •C ^ if very variable. I he number of costal vertebrae side of each posterior articular process presents an apex nes 10m , which is that of the Chinese monkey, com- turned backward, so that the anterior articular process of mon a , arnia i o, helmet-headed dolphin (delphinus glo- the next vertebra is locked between two eminences, which iceps), am angetic dolphin, to 23, which is that of the confine its movement much. Though this apex is found 76 ANATOMY. Compara¬ tive Anatomy. in the Rodentia, it is there shorter; and the arrangement is wanting in the other tribes. The size of the transverse processes indicates the strength of the loins,—a fact which is evinced especially in the instance of the horse, porpoise, &c. Sacral ver- The number of sacral vertebrae is still more various, tebrae. even jn the species of the same genus. Thus, while in several of the ape genus, in the lori, in the vampyre bat, the colugo (galeopithecus), the coati, and two of the didelphis, there is one sacral vertebra only, most of the apes have sacra consisting of 2, 3, 4, 5, or 6 pieces ; the majority of other animals have 3 sacral vertebrae; the hedgehog, porcupine, guinea pig, paca, hare, tiger, several of the murine genus, the ant-eater, rhinoceros, camel, dro¬ medary, chamois, goat, sheep, and ox, have 4; the ele¬ phant has 5; the Ai 6; the Uhau 7; and in the mole, white bear, and quagga, they also amount to 7. The fre¬ quency of the three sacral vertebrae in the lower animals shows that Galen, who ascribes only 3 to the human sub¬ ject, must have derived this inference from the former. These vertebrae are in the mammalia narrower than in man, and their direction forms with the spine, instead of receding backwards, a straight line ; an arrangement evi¬ dently connected with the horizontal position of the for¬ mer. The shape of the sacrum in the lower mammals is that of an elongated triangle ; and it is further remarkable, that in those species which occasionally assume the erect attitude on the hind leg, as apes, bears, and sloths, the width of the sacrum is proportionally greater. The sa¬ cral spines, which are short in man and the ape, become longer in the Zooph ag a, and form a continuous ridge in the rhinoceros, most ruminants, and especially in the mole. In the vampyre bat the sacrum forms a long compressed cone, the extremity of which is united to the ischial tu¬ berosities, without sustaining a coccyx. The seal has two sacral bones ; but the Cetacea, e. g. the dolphin and por¬ poise, are void both of sacrum and coccyx. The coccygeal bones constitute the tail of the lower animals, and in many instances they are extremely nume¬ rous. The smallest number is 3, which is that of the magot (simia, sylvanus, pithecus, et inuus) or Barbary ape ; and the greatest yet known is that of the ant-eater, in which they amount to 40, and the long-tailed manis, in which they amount to 45. Next to these may be placed that of the coai'ta 32, the baboon 31, the phalanger {di¬ delphis orientalis) 30, the marmoset {didelphis marina) 29, the pangolin 28, the silky monkey {simia rosalia) and black rat 26, the weeping monkey and howling ape 25 ; the panther, mouse, dormouse, and elephant, 24; the lion, beaver, water-rat, Norway rat, and field-rat, 23 ; the flying- cat, puma, cat, dog, marmot, and rhinoceros, 22; the otter, 21; the Chinese monkey, raccoon, civet, hare, and rabbit, 20; the tiger and wolf, 19; the macauco, glutton, marten, fat dormouse, dromedary, giraffe, and quagga, 18; the tarsier, shrew, camel, and horse, 17 ; and other genera and species, without any determinate order, descending so low as to 9, 8, 7, 6, and 4. The quilled duckbill {echidna, ornithorhyncus hystrix) has only 12 caudal vertebrae, while the common one {ornithorhyncus paradoxus) has at least 20. The gibbon and vampyre bat are the only mammifer- ous animals, excepting the Cetacea, in which there are no coccygeal bones. It sometimes happens that a monkey or opossum loses a portion of its tail, when the truncated end is converted into a knotty excrescence, sometimes carious, always different from the taper point of the last coccygeal vertebra; and in this case it is difficult to de¬ termine the exact species. In the Cetacea, in which the absence of pelvis affords no mark to distinguish the lower vertebrae into lumbar, sacral, and coccygeal, those below the dorsal may be re¬ el. Lc Lamantin 16 24 Dugong 18 28 Dolphin 13 47 Tursio .13 38 D. Globiceps 11 37 D. Griseus 12 42 D. Gangeticus 11 28 Coccygeal or caudal vertebrae. garded as lumbo-coccygeal; and their number is estimated Compara. by deducting that of the cervical and costal from the total hve number. The following table, which shows the number of the costal, the lumbo-coccygeal, and the total number of vertebrae, indicates that their number varies much in various genera of this family. t. d. l.c. t. 46 Porpoise 13 40 60 46 Narwal 12 35 54 67 Hyperoodon 9 29 45 58 Cachalot or White 56 Whale 14-15 39 60 61 Greenland Whale... 15 37 59 46 Rorquhal 14 31 52 In general, however, if we reckon the first 2, 3, or 5 ver¬ tebrae after the costal as lumbar, it may be said that the caudal vertebrae of the Cetacea vary from 22 or 25, which are the numbers respectively in the lamantin and dugong, to 34, 38, and 42, at which they may be estimated in the dolphin. We shall see that, in the dugong at least, we are guided in this estimate by the rudimental bones of the pelvis. The coccygeal or caudal vertebrae of the Mammalia may be distinguished into two kinds; those which con¬ tain a canal in continuity with that of the vertebral co¬ lumn and sacrum, and those in which the pieces are solid. The first, which are next the sacrum, have articular, transverse, and spinous processes, distinct in proportion as the animals move their tails. The latter are generally prismatic in shape, diminish in size towards the extre¬ mity, and have only slight tubercles for muscular attach¬ ments. Animals with prehensile tails, as the American ape {sapajous), have above, at the base of the body of each vertebra, two small tubercles, between which pass the tendons of the flexor muscles. By means of this mechanism these animals can twine the tail round the branch of a tree with sufficient force to support the weight of the body. The Mammalia with long mobile tails have often two or three small supernumerary bones placed on the lower surface of the junctions of several of the coccygeal ver- tebrae, from the 3d or 4th to the 7th or 8th. These sesamoid bones give attachment to muscles. In the beaver, which employs its tail as a trowel, the transverse processes are remarkable for size, while the lower spinous processes are larger than the upper ones,—an arrangement which enables it to depress the tail forcibly when it beats the ground. The shape of the chest in the Mammalia varies in The chest general as the clavicles are present or wanting. In ani¬ mals provided with clavicles, as the Quadrumana, bats, the squirrel, beaver, mole, ant-eater, hedgehog, and sloth, the shape of the chest approaches to the human, or is conoidal, and flattened before and behind. In those void of clavicles it is compressed laterally, from the smaller in¬ curvation of the ribs ; and the sternum makes a remark- The ster- able prominence, so that the transverse or intercostal dia-nuni- meter is less proportionally, and the sterno-vertebral is greater proportionally, than in man and the claviculated animals. In the long-legged animals, as the giraffe and those of the stag kind, this prominence of the sternum is sufficient to give it a keel-like appearance {thorax carina- tus). In the carnivorous animals the chest presents its greatest longitudinal extent. The number and shape of the ribs varies in the differ- The ril ent tribes. In number, indeed, the ribs always correspond with that of the costal vertebrae. Thus, in the Quadruma¬ na, Zoophaga, Rodentia, Edentata,and Ruminantia, they vary from 12 to 15 pair, with only three exceptions, the glutton, hyena, and ant-eater. In the Chinese monkey, common bat, and armadillo, they are a pair less than in A N A 1 Conijiara- man. While tlie quillet! duckbill (echidna, ornithorhyncus Ibve hystrix) has only 15 ribs, the common duckbill (ornithor- Anatomy. ]tyUCUS paradoxus) has 17; the horse and quagga have 18, the rhinoceros 19, the elephant and tapir 20, and in the U7iau or two-toed sloth they amount to 23, which is the greatest known number. On the whole, the most prevalent number is 13. In the carnivorous animals they are narrow and dense in structure. In the herbivorous they are large, broad, and thick. In the armadillo the two first ribs are large compared with the others. In the two-toed ant-eater, which has 16 pairs, the}' are so broad that they are imbricated over each other like the plates of a corslet, and render the parietes of this animal’s chest exceedingly solid. In the two species of duckbill (orni¬ thorhyncus paradoxus and hystrix ; echidna of Cuvier), the true ribs, in number 6, consist of two portions—a long or vertebral joined to the spine, and a short or sternal at¬ tached to the sternum. These portions are united by cartilage, so as to resemble the ribs of birds. The 9 or 10 false ribs terminate before in broad, flat, oval plates of bone, which are mutually connected by elastic ligaments. The sternum, which is broad in the ourang and pongo, is narrow in the other species of ape, and consists of seven or eight pieces. In the vampyre and all the bat family it is narrow, but presents before or below rather a promi¬ nent azygous ridge or keel (carina), and an anterior ex¬ tremity, broad on the sides, like a T, for receiving the clavicles. In the mole the clavicular extremity of the sternum is continued before the ribs, and is flat on the sides for receiving the two short clavicles. In the hog the sternum is broad behind and narrow before. In the rhinoceros, horse, and elephant, it is prolonged before and flat on the sides. In the Cetacea it is broad and thin, especially before. Cranium. Though the Quadrumana have 8 cranial bones, the sphenoid often consists of two portions, one forming the orbitar wings and the anterior clinoid processes, the other the temporal or large wings, the posterior clinoid processes, and the basilar fossa. The two parietal bones are early united into one in the Chiroptera and the other Zoo- phaga, in which, however, the frontal remains biparted by a middle suture. The temporal tympanum is separat¬ ed from the rest of the bone by a suture, which is seldom obliterated in the feline, canine, and viverra genera. The temporal tympanum is also separate in the Rodentia, and the frontal ununited. The parietal is united in some, as the hare, the porcupine, cahia, marmot, rat, and squirrel; se¬ parate in the mouse, fat dormouse, and rabbit. The frontal and parietal bones of the elephant are early united with the other cranial bones, and form a vault without trace of suture. In the hog, tapir, and hippopotamus, the two parietal bones form one piece, while the frontal bone is biparted ; and though in the rhinoceros both are biparted, the frontal is early united into one portion. The sphe¬ noid bone of the animals of this tribe long consists of two pieces, one forming the orbitar wing; the other the tem¬ poral wings, which, it is to be further observed, are the smallest, in opposition to their proportional dimensions in man. In the Ruminants and Solidungula the frontal remains long parted by its middle suture; but the two parietals are represented by a single bony vault. The tympanum is always distinct from the temporal bone. In the seal and walrus the parietal and the frontal con¬ sist of two pieces. The lamantin has only one bony arch, representing the two parietal and the squamous part of the temporal bones, while the temporal tympanum is de¬ tached from the rest of the bone. In the other Cetacea the parietal bones are at an early period united to the oc¬ cipital and temporal bones, so that the five form one solid poition. The auditory or pyramidal bone is always de- " O M Y. 77 tached from the temporal, and adheres to the cranium bv Compara- soft parts only. The sphenoid is not only long separate, tive but consists of several portions. Anatomy. 1 hough, among the Quadrumana, the cranium of the ourang-outang approaches that of man in shape, it differs nevei theless in the connections of the constituent bones. J he temporal wing of the sphenoid bone is very narrow, does not reach the parietal, and touches the frontal only by its upper extremity, so that the temporal bone is part¬ ly articulated with the frontal. The temporal suture is not imbricated, but serrated. The same mode of connec¬ tion is observed in the mandrill, macaca (s. cynocephalus), magot, and guenon (Cercopithecus), or tailed monkey tribe. In the American monkey the temporal win<* of the sphenoid touches neither the frontal nor the panetal bones ; but the temporal bone is articulated directly with the malar by its flat portion. In the American monkeys the frontal bone does not touch the temporal wing of the sphenoid, and the parietal is articulated to the malar. In the howling ape (simia heelzebul) the connections are as in man. The connections of the cranial bones are in the Zoo- Connee- phaga the same as in man. In the Rodentia the sphenoid t‘olls- is joined to the frontal and temporal, without touching the parietal; and the orbitar and temporal fossce are very small. In the armadillo, pangolin, and sloth, the connections are as in the Rodentia ; but in the ant-eater the parietal bone, continued below the cranium, is united to the sphe¬ noid at the posterior part of the orbito-temporal fossa:. In the elephant, though the cranial bones are at an early period consolidated into one, the auditory is always distinct from the temporal bone. In the hog, tapir, rhi¬ noceros, and hippopotamus, the sphenoid is united to the - parietal bone, and its temporal wings occupy a small space only of the orbitar and temporal fossae. The orbi¬ tar wings, though larger, appear small externally. The auditory bone, though distinct, is, however, united by its base to the margin of the auditory canal of the temporal bone. The sphenoid of the ruminants is articulated, as in man, with all the cranial bones; but its orbitar wing, which is extensive, is principally concealed within the cerebral cavity, and covered by the orbital part of the frontal bone. In the Cetacea generally, all the sutures which remain after early life are squamous or imbricated. The outline of the frontal bone in the ourang-outang is more irregular than in man, and the orbitar arches are less surbased. In the American monkeys its outline is triangular, and terminates in a point towards the vertex. In the others of this family (Simia), this bone is almost elliptical, and the orbitar arches are nearly straight; and in the whole family these arches form, as in man, the an¬ terior border of the frontal bone, in consequence of the narrowness of the root of the nose. In the makis it be¬ gins to widen, and the eyes become oblique,—a circum¬ stance which gives their frontal bone a rhomboidal shape. The frontal bone in the Zoophaga, and in all the subse¬ quent Mammalia, except the Cetacea, forms an irre¬ gular prismatic or cylindrical surface with three faces—a superior, bounded before by the muzzle, behjnd by the cranial convexity and two lateral, descending into the or¬ bitar and temporal fossce on each side. The hedgehog, mole, shrew, ant-eater, some of the phocce, the morse or walrus, and the rhinoceros, have no proper orbitar arches; and the frontal bone, though broad behind, is contracted and nearly cylindrical between the orbits. In the hippo¬ potamus, the ruminants, and the onedmofed animals, it enlarges, and forms a vault over each orbit. Lastly, in the Cetacea it is narrow from before backward, resem¬ bling a fillet stretched across the cranium, but descends beneath the maxillary bones to form the floor of the orbit. 78 A N A T Com para- The parietal bones of the ourang-outang differ from tive those of man only in their temporal margin being nearly Anatomy. straight. Those of the ape are narrower, and become more oblique-angled as the cranium is flattened. In the Zoo- phaga and Edentata they are almost rectangular. The single parietal of the RodentiaIs nearly quadrilateral; but it is sometimes flat, sometimes rounded, sometimes sur¬ mounted by a crest. Of the single parietal bone of the ruminants, that of the stag, most of the antelope genus, the sheep and the goat, is broad, and sends on each side a narrow process into the temporal fossa before the occi¬ pital arch; in the camel it is narrower, and bears a lon¬ gitudinal crest; and in the ox and antilope bubalus it is placed behind the occipital crest, and resembles a fillet surrounding the back of the head transversely. In the Solidungula the single parietal is nearly quadrilateral, and placed before the occipital crest. The occi- The occipital bone in the lower mammalia is remark- pital bone, for fjVe characters. 1. The proper occipital surface, instead of being oblique or horizontal, and inferior or ba¬ silar, becomes vertical and posterior. 2. The plane of the occipital hole forms with that of the orbits an angle constantly diminishing, becomes parallel to the orbitar plane, and at length crosses it above the head. 3. The plane of the occipital condyles, instead of being transverse and horizontal, becomes oblique, and at length vertical. 4. The basilar or cuneiform process is not only hori¬ zontal, but forms with the occipital a right angle. And, 5. The mastoid process, which in man and the ape forms part of the temporal, belongs in the other mammalia to the occipital. In the polar bear, however, the mastoid process constitutes part of the temporal bone. From the 1st, 2d, and 3d characters, it results that the head of quadrupeds is not balanced on the spine, but is suspended by muscles, tendons, and ligaments, especially the strong cervical, which connects the occipital spine to the spinous processes of the cervical and dorsal vertebrae. This ligament, therefore, though feeble and indistinct in man, is strong, particularly in quadrupeds with heavy head or long neck, in order to counteract the disadvantage of the long lever. It is strongest in the elephant, and is almost wholly ossified in the mole—a condition requisite for the burrowing faculty exercised by that animal. The tern- The temporal bone is naturally distinguished in the poral bone. Mammalia into two parts ; a flat or proper temporal, cor¬ responding to the squamous part of the human temporal bone, and the pyramidal, acoustic, or auditory, correspond¬ ing to the pyramidal or lithoid portion of the human sub¬ ject. The first only, which is proper to the scull, claims attention here. In the ourang-outang and most of the genus simia it forms a trapezium with the longest side above, and the height of which varies with that of the scull. In the American apes it is smallest in this direc¬ tion. In the Zoophaga the proper temporal bone is as in the ape. Being narrow in the Rodentia behind, it is a little rounded in the short-muzzled Edentata, the Rumi- nantia, and Pachydermata. The ethmoid is, strictly speaking, the olfactory bone, and shall be mentioned under the organs of sense. The sphenoid, among other offices, may be regarded as the essential ophthalmic bone. The facial The facial bones of the lower Mammalia differ from bones. those of man ; first, in the number of separate pieces; and, secondly, in the form and proportional horizontal ex¬ tent. Intermax- The difference in number consists in each superior max¬ illary iuary being divided into a maxillary bone proper, and bones* an anterior or labial portion; which being interposed be¬ tween the proper maxillary, are commonly denominated the intermaxillary (ossa intermaxillaria). As it bears also the O M Y. superior incisors, it is named by Haller the incisive bone Compara. (os incisivum); but since it is found not only in the rumi- tive nants, which, excepting the camel, are void of incisors, but in the Edentata and Cetacea, this denomination is less applicable than the former. It ynuy be doubted whether these should be regarded as additional bones, as they are generally represented by zootomists ; for they are in truth merely the incisive or anterior portion of the superior maxillary bones. In other respects, the difference be¬ tween the human and the animal superior maxillary bone is, that in the former each bone is in one piece, in the latter it is in two. Even in the human foetus the trace of the separation may be recognised ; and we have seen it in the human scull some years after birth. Conversely, it is early obliterated in some quadrupeds. Thus, though distinct in the ourang-outang seen by Cuvier, it was not found by Tyson or Daubenton, and is wanting in one pre¬ served in the Hunterian museum. In a young specimen of the jocko also, noticed by Cuvier, no trace of the in¬ termaxillary suture was observed. It appears also to be wanting in the perforated bat, the horse-shoe bat, and the three-toed sloth. Mutually united on the mesial plane, the intermaxillary bones are united to the maxillary by sutures, which pass from the outer angles of the latter, near the incisive holes, towards the palate, where they intersect. In form and size it varies in the different orders and genera. Small in many of the Zoophaga and the walrus, it is large in the Rodentia, in the hippopotamus, porpoise, and cachalot, and prominent in the wombat. In the duckbill it consists of two unciform portions, united by a broad intermediate cartilage. The peculiarity of the animal face consists in the ho- Elongation rizontal elongation of the two jaw-bones. In the monkey of the face, tribe this elongation is trifling; and all that is remarked is, that the palate and maxillary bones are more elongated in proportion to their height, and that their anterior part, instead of being vertical, is more or less inclined forwards. The degree of this elongation, which differs in different genera, may be estimated by the acuteness of the facial angle. The narrowness of the interorbital space is another Interorbi- character of the animal countenance. In the guenon and tal region. American ape it is a mere septum ; but in the ourang- outang, magot, and howler, it is larger, by reason of the nasal fossce ascending to this height. From these the face of the Zoophaga is distinguished by the following circumstances. 1. The breadth of the ascending maxillary processes throws the orbits to the sides; 2. these orbitar surfaces form the anterior wall instead of the floor of the orbit; 3. the malar bone is united neither to the frontal nor to the sphenoid bone, and forms only the zygomatic arch and the lower margin of the orbit; 4. the orbit, clos¬ ed neither behind nor below, communicates freely with the temporal fossa ; and, 5. the palate bones are much elongated and form a considerable spacg of the internal wall, to which the ethmoid bone does not contribute. In the Rodentia the interorbital space is still larger, by rea¬ son of the size of the intermaxillary bones throwing the maxillary backwards and to the sides, where they form the inner orbitar wall, in which the palate bones occupy only a small space. The anterior wall is formed by a process of the maxillary, which contributes to form the zygomatic arch, while the malar is suspended in the middle between the process and that of the temporal bone. Very similar is the face of the elephant, except that the height of the alveoli from the tusks, thrusting the nose upwards, and shortening its bones, alters entirely the expression of the head of this animal. In the sloth, in which the face is short in proportion to ANATOMY. Orbits. Com para- the scull, the malax* bone attached to the maxillary only, tive is not united to the zygomatic process of the temporal. In Anatomy. ]ong_muzz]ecl Edentata,in which the face is conoidal, the maxillary bones extend to the orbits, and are separat¬ ed by a broad lacrymal bone, while a long palate bone forms the inner wall of these fossce. The zygomatic arch, which is interrupted in the ant-eater and pangolin, is com¬ pleted in the Cape ant-eater and the ai-madillo. In the tapir and rhinoceros the maxillary bone passes beneath the orbit; and the nasal bones form a sort of vault, which supports in the fii'st animal the trunk, and in the second the horn. In the Cetacea the maxillary and intermaxillary bones form a sort of flattened beak, distinguished into four paral¬ lel bands, of which the maxillary, which are external, alone bear teeth in three genei*a, provided with the latter organs. The nasal fossa is a vertical opening before the cranium, surrounded before and laterally by the intermaxillary bones. The maxillary ascend in the same manner, and cover that part of the frontal bone which forms the orbitar vault, but do not themselves contribute to the formation of this cavity. The nasal bones are two minute tubercles implanted on the frontal bone above the narrow aperture. The malar is in the shape of a style, suspended by cartilages beneath the orbit; and the latter cavity is completed be¬ hind by a process of the frontal, which joins the zygoma¬ tic of the temporal bone, and below which the orbitar and temporal /b.ss with the exception of the Ruminants, in which these bones are in early life consolidated into one named the cannon bone. In animals which walk on the tips of the toes, or which use them as organs of prehension, the metacarpal bones are lengthened to nearly double; and hence in all these animals the metacarpus is erroneously named the fore leg, and therefore it has been imagined, that in several 82 ANATOMY. Anatomy. Fore toes. Compare of our domestic animals the different parts of the lower ex- tive tremity are articulated in opposite directions to those of man. Thus the fore leg of the horse, deer, sheep, and dog are in truth the metacarpus of these animals; and what is vulgarly named the fore knee or cannon bone of the horse, is actually the carpus or wrist-joint. It is there¬ fore convex on the dorsal, and concave and inflected on the palmar aspect, exactly as the carpus of the human subject. In the three-toed sloth, the three bones of which the metacarpus consists are mutually consolidated at the base and with the rudiment of a fourth toe. In the Cetacea, the metacarpal bones, which are much flattened, are also mutually united. In the Mammalia generally, if we include imperfect or rudimental phalanges concealed in the skin, there are never fewer than 3, nor more than 5. The Unguiculated ani¬ mals generally have 5, perfect and imperfect- The cha¬ racter of the perfect fore toe or finger is to consist of 3 rows or phalanges, excepting the first of the radial side, which has only 2. In the Quad Humana this is separate, and opposable to the other toes, constituting a thumb, and giving this tribe of animals a prehensible organ en¬ titled to the epithet of hand. It is, however, shorter and less perfect in other respects than the genuine thumb of the human hand. In the codita (simia paniscus) it is con¬ verted into a rudimental bone, concealed under the skin. In the Zoophaga, which have no power of grasping mi¬ nute objects, the thumb or first toe is parallel to the others, and, though equal in length to these in the ursine family, it is shorter in the mustela, viverra, canine and feline ge¬ nera. In the latter, which have the power of erecting the claws, to prevent them from being blunted in walking, the shape of the middle and unguinal phalanx is remark¬ able. The former is triangular prismatic, with two late¬ ral and a plantar or palmar inferior surface. The third or unguinal phalanx is shaped like a hook, consisting of two parts. One, directed forwards, sharp and pointed, receives the nail or claw, in a long groove like a sheath. The second part of the hook, which is behind, rises verti¬ cally from the lower part by which it is articulated, and is produced into two processes, to which are attached the erecting muscles of the claw, which are flexors of the phalanx. Among the Rodentia there is a perfect but short thumb in the hare, beaver, and jerbois ; a two-phalanxbut conceal¬ ed one in the squirrel, mouse, and rat family, porcupine, paca, agouti; and a one-phalanx concealed one in the cavy, guinea-pig, marmot, &c. In the Edentata the number of fore toes varies much ; in the Tamanoir, and Tamandua or four-toed ant-eater, the thumb-toe is oblite¬ rated ; in the Ai or three-toed sloth, both that and the fifth toe are obliterated; and in the two-toed ant-eater, and Unau or two-toed sloth, these, with the second toe also, are obliterated. The elephant has 5 perfect toes, all concealed under the thick, callous hide of the foot. In hoofed animals with 4 toes, for instance the hog, tapir, and hippopotamus, the ihumb-toe is in the shape of a small rudimental bone. In the Ruminants the single metacarpal bone (Chesel- den’s figure of the Deer, Plate I.) is articulated with two digital phalanges, which constitute one of the distinguish¬ ing characters of this order—the cloven foot. In some genera, at the root of these twro perfect toes are two small bones, often covered with horn, which represent two other toes. The last or unguinal phalanx is always trilateral in shape. In the horse and the Solidungula generally, the two lateral toes are represented only by two bony styles, named the splint bones, situate on the two sides of the metacarpal or cannon bone. The three phalanges of The fore cannon bone. the single toe which constitutes the foot are distinguished Compara. as the pastern bone, which is the first phalanx ; the coro- the net, which is the middle or second; and the coffin bone, which is the third or unguinal phalanx, which has the shape of the hoof, rounded before, convex above, and flat below. To the back of the pastern joint are connected two sesamoid bones ; and to the coffin bone is attached another, named the shuttle bone. In the Cetacea, all the phalanges, which are flattened, and often cartilaginous, are united in the fin or paddle. .... The thigh-bone, which is single in all the classes, fol- Thigh- lows the type of that of the human frame in general figure bone, and parts. In the Mammalia it is, however, proportion¬ ally shorter, and its length diminishes as that of the me¬ tatarsus ausrnents. In the Ruminants and Solidungula, for instance, it is so short that it is concealed by muscles against the belly; and hence it is too often overlooked and confounded with the leg. In other respects the ge¬ neral characters are, that it is not arched ; that, excepting in the bear and some of the simia genus, e. g. the ourang- outang, it is shorter than the leg-bones; that its neck is very short, and more perpendicular to the axis of the diaphysis than in man; and that the great trochanter is raised above the head, which is directed inwards. In the simice it is quite cylindrical, and void of linea aspera. In the tapir the middle part is found flattened; and at the external margin there is a prominent crest, terminating in an unciform process. In the rhinoceros the great tro¬ chanter and the unciform process are so elongated as to unite almost, and form a hole between them and the dia¬ physis. The unciform process is observed also in the horse, beaver, and armadillo. The thigh-bone of the seal is so short, that the half of its length consists of the two articular extremities. Though the leg-bones of the Mammalia bear a general Leg-bones similitude to those of man, the tibia alone is constant; and the fibula, after becoming unusually slender, and chang¬ ing its position from the outside to the posterior part of the tibia, is converted into a mere appendage, and at length disappears entirely. Thus, though it is distinct, and occupies its usual position in the simice, in the Chirop- tera it is extremely slender; and since the femora are directed backward, the fibulce are turned towards each other. In several of the Edentata, for instance the pha- tagin, armadillo, and sloth, it is large, curved, and remote from the tibia. In the dog family and the Rodentia it is altogether behind the tibia. In the mole and murine genus it is consolidated to the lower third of the tibia, leaving an empty trilateral space above. In the rhinoceros, ele¬ phant, and hog, the fibula is flattened and united to the whole length of the tibia. In the ruminants it is repre¬ sented by a small bony appendage, placed on the outer margin of the astragalus, below the tibia, and forming the external or fibular ankle. Lastly, in the horse and Soli¬ dungula, thefibula is reduced to a styloid rudimentai pro¬ cess, which is firmly consolidated in the adult animal to the upper part of the tibia. Between the tarsus of man and that of the other Mam¬ malia the following are the principal differences. In the simice the fibular facette of the astragalus is I he tar- nearly vertical, and the tibial is very oblique; and the sus‘ calcaneum wants the tuberosity, except in the pongo. In the ordinary bat family the calcaneum is elongated into a styloid process, concealed in the substance of the mem¬ branous ubiform expansions; but in the roussette (jptero- pus) the tuberosity projects beneath the foot. In the Rodentia the calcaneum is produced consider¬ ably backwards, while the scaphoid, which consists of two parts, forms a tubercle on the sole. Among the Eden¬ tata the three-toed sloth is peculiar in having a tarsus, ANATOMY. 83 Compara- consisting of four bones only, tlie astragalus, calcaneum, and live two cuneiform bones, the first of which is articulated not Anatomy. on]y the tibia, fibula, and calcaneum, but with the large cuneiform bone, without any intermediate scaphoid bone. Its connection with the tibia is by means of a con¬ vex articular surface, which rolls on the external part of the tarsal end of the tibia. From this mode of articula¬ tion it results that the foot of the sloth admits neither of being elevated nor depressed, but simply of performing lateral motions of adduction and abduction, to which it owes the power of clasping the trunks of trees and climb¬ ing, but which renders progression difficult and laborious. The hog has a scaphoid with three ordinary cuneiform hones, and a rudimental great-toe bone beneath the first. In the tapir and rhinoceros there are only two cuneiform hones. All the animals already enumerated have the same number of metatarsal bones as of toes. In the Ruminants the cuboid and scaphoid bones are united, unless in the camel, in which they are distinct. At the outer margin of the pulley of the astragalus is a bone which represents the lower head of the fibula, and which is farther articulated to the upper surface of the os calcis. In this side also there are only two cuneiform bones, which are united in the giraffe. The two meta¬ tarsal bones are always united, as in the metacarpus, into Third can-one, which forms a posterior cannon bone. The Soli- non bone, dungula resemble the camel in this, that the scaphoid is distinct from the cuboid bone, and that there are two cuneiform bones, while the peroneal rudiment and the corresponding articular surface of the calcaneum are want¬ ing. The metacarpal are also consolidated into a single piece, named the hinder cannon bone, each side of which is provided with a minute bony style. Hind toes. The toes of the Quadrumana and the Marsupialia are longer than those of man ; but the great toe is shorter than the others, and its metatarsal bone is susceptible of separation and opposition, as the thumb or thumb-toe of the hand. Hence Cuvier, in his first classification, dis¬ tinguished the latter by the name of Pedimana. The Aie-aie among the Rodentia appears to possess the same faculty. Among the Zoophaga the great toe remains always conjoined with and parallel to the ethers; and in the canine and feline genera it is obliterated. Among the Rodentia, that of the beaver is nearly equal to the other toes; those of the marmot, porcupine, and the murine genus, are shorter; in the paca it is almost obliterated; it is reduced to a single bone in the Cape gerboa; and the leporine genus have no trace of it. In the cavy, agouti, and guinea-pig, the great and small toes are each reduced to one bone. In the gerboa (mus jaculus) and alactaga {mus sagittd) the three middle metatarsal bones are united into a single one similar to the cannon bone of the Ruminants and Solidungula ; and while the two la¬ teral toes are distinct, though short, in the former animal, they are obliterated altogether in the latter. Among the Edentata, the ant-eater, orycteropus, pan¬ golin, and armadillo, have five toes, of which the great is the shortest in all. In the sloth the great and small toe are reduced to one small bone. The other metatarsal bones are united at their base. The toes have only twro phalanges, of which the unguinal are the largest. In the subsequent families the metatarsal bones de¬ serve particular attention. In the elephant and Pachyder- mata, their tarsal extremity has a flat surface, and the phalangeal consists of a convex tubercle, which presents below a prominent line in the middle of the bone. In the Solidungula this line is above and below both. In the Ruminants, in which the cannon bone consists of the two metatarsal bones, the line of union is represented by a deep line like the tract of a saw. The elephant has 5 perfect toes; the hog 4; the tapir and rhinoceros 3; the Compara- Ruminants have two perfect toes on one metatarsal bone, flve and two small ones attached behind its base. The So- vAn_atomT- lidungula have one perfect toe, and two imperfect, which are reduced to a single styloid bone. In these animals the body is supported in walking by the last or unguinal phalanx alone; and hence the term foot is not of the same import as in the human subject and animals simi¬ larly constructed. While indeed man supports his person in progression on the os calcis and the posterior or meta¬ tarsal phalanges, in the other mammiferous animals the former bone touches not the ground, but is always elevated above it a considerable height. All the zoophagous or unguiculated animals, excepting the plantigrade, support themselves chiefly on the unguinal and middle phalanges both of the fore and hind foot; and neither the posterior phalanges nor the calcaneum touch the ground, as is easi¬ ly demonstrated on observing the gait of the hedgehog, dog, fox, cat, or similar individuals of the same family. The animals distinguished by the name of Plantigrade are believed to support themselves on the entire foot. But though the foot is certainly spread on the ground more freely than in those already mentioned, by the bear, glutton, badger, and others, it appears that not the heel, but the metatarsus, is allowed to touch the ground in pro¬ gression. In the Ruminants and Solidungula, as already mentioned, the only part of the foot which is applied to the ground is the unguinal phalanx; and it is well known that the horse supports himself on the plantar surface of the coffin bone only. Lastly, in the Amphibious Mammals, while the extreme brevity of the humerus femur unfit them for progression on land without extreme awkwardness and difficulty, the expanded shape and oblique position of the metacarpal bones and phalanges, the length of the tibia and fibula, and the greater length of the first and last than the middle metatarsal phalanges, all concur to give these animals great facility in swimming. (Cuvier, Ossemens Fossiles, tome v. partie i. septieme partie.) In the Cetacea, again, while the total want of pelvic extremities renders motion on land quite impracticable, the fin-like disposition of the metacarpus and metacarpal phalanges, with the great strength of the lumbar, and the length of the coccygeal vertebrae, peculiarly qualify them for locomotion in the waters. sect. ii.—osteology of birds. Plate X.XXIV The number of vertebrae of which the different regions ^ 3 of the spine consist, is not less variable in Birds than in ^ the Mammalia. Some idea of these variations may be formed from the number exhibited in the following table by Cuvier. Species. Vultur. Vulture Falcofulvus. Eagle — haliaVtus. Bald buzzard — foiteo. Buzzard — nisus. Sparrow hawk — milvus. Kite Strix bubo. Eagle owl Strix ulula. Brown owl Muscicapa grisola. Fly-catcher Turdus merula. Blackbird Tanagra tatao. Tanagra Conus corone. Crow pica. Magpie glandarius. Jay Sturnus vulgaris. Starling Loxia coccothraustes. Grosbeak — pyrrhula. Bullfinch...... Vertebras Vertebrae Sacral Coccygeal Spine. of Neck, of Back. Vertebras- Vertebra1. 13 13 14 11 11 12 13 11 10 11 10 13 13 12 10 10 10 11 17 11 10 11 11 12 11 10 10 9 13 13 11 10 12 11 A N A T O 84 Compara¬ tive Anatomy. Fringilla domestica. Sparrow... cardnelis. Goldfinch... Parus major. Titmouse Alauda arvensis. Lark Motacilla rubecula. lled-breast Hirundo urbica. Swallow Species. Caprimulgus Europceus. Goat- | sucker j Trochilus pella. Colibri Upupa epops. Hoopoe Alcedo ispida. King’s fisher... Picus viridis. Woodpecker Ramphastos. Toucan Psittacus erithacus. Parrot Columba cenas. Stockdove Pavo cristatus. Peacock Phasianus colchicus. Pheasant Meleagris gallopavo. Turkey.., Crax nigra. Curassow bird. | Hocco J Struthio Came/us. Ostrich Casuariut. Cassowary... Phoenicopterus. Flamingo Ardea cincrea. Heron alba. Stork grits. Crane Platalea A'iaia. Spoonbill Recurvirostra. Avoset Charadrius pluvialis. Plover... Tringa vanellus. Lapwing Scolopax rusticola. Woodcock... arquata. Curlew Hcemutopus. Oyster-catcher... Rallus crex. Hail Fulica atra. Coot Parra. Jacana Pelicanus onocrotalus. Pelican... carbo. Cormorant... Sterna hirundo. Sea swallow... Earns. Gull Procellaria. Petrel Anas cygnus. Swan — anser. Goose — bernicla. Bernacle......... — boschas. Duck — tadorna. Sheldrake — nigra. Black diver Mergus merganser. Merganser Colymbus cristatus. Grebe... Vertebra; of Neck. 9 11 11 11 10 11 11 12 12 12 12 12 12 13 14 13 15 15 18 15 18 18 19 19 17 14 15 14 18 13 12 13 15 14 16 16 14 12 14 23 15 18 14 16 15 15 14 Vertebra; of Back. 8 11 7 7 7 9 7 9 8 8 7 8 9 8 9 8 7 9 8 8 8 11 10 10 8 11 9 8 10 Sacral Vertebra:. 10 11 11 10 10 11 11 9 10 8 10 12 11 13 12 15 10 10 20 19 12 10 11 12 14 10 10 10 13 10 15 13 7 12 14 14 10 11 14 14 14 15 11 14 13 13 Coccygeal Vertebra;. 8 7 7 9 7 8+ 7 8 5 5 Cervical vertebrae. Dorsal vertebrae. Neck. In this table the most remarkable circumstance is the great number of cervical vertebrae, which are much more numerous than in the Mammalia. They vary from 9, the number in the sparrow, to 23, which is that of the cervical vertebrae of the swan. The most common num¬ ber is 11, which is that of 10 genera. The next most fre¬ quent is 12, 13, and 14, which are equally the numbers of 9 genera. The next is 15, which is that of 8; 10 oc¬ curs in 6, 18 in 4, and 16 in 3. In the stork and crane they are 19. The next remarkable circumstance is, that the dorsal or costal vertebrae are greatly fewer than in the Mam¬ malia, never exceeding the number of 11, and being more frequently about 7 or 8. Thus, while they are 11 in the cassowary, swan, and sheldrake, 10 in the goose, bernacle, and grebe, and 9 in the sparrow, lark, humming-bird, parrot, crane, avoset, oyster-catcher, cormorant, and black- diver, they are 7 or 8 in all the other genera, and only 6 in the bullfinch. There are no lumbar vertebrae strictly so named, for those which extend from the chest to the tail are con¬ solidated into one piece with the iliac bones. The tail, which is short, consists of from 7 to 9 vertebrae. The part most variable in proportional length is the neck. It is so much longer as the feet are elevated, ex- M Y. cept in some of the swimmers, in which it is greatly Compara- longer, because they require to seek their food below the five surface of the waters on which they float. The bodies of the cervical vertebrae are articulated not by plane facettes, which would admit obscure motion only, but by portions of cylinders, which allow extensive mo¬ tion. The 3d, 4th, or 5th superior vertebrae allow of an¬ terior inflection only, and the others of posterior inflection. This gives the necks of birds an alternate serpentine in¬ flection ; and it is by rendering the two arches, of which this curvature consists, straight or convex, that the ani¬ mal elongates or shortens his neck. The articular pro¬ cesses of the superior vertebrae are directed upwards and downwards; those of the lower are turned anteriorly and posteriorly. Instead of transverse processes, the cervical vertebrae of birds are provided with a tubercle above, and the anterior extremity of which terminates in a narrow style, descend¬ ing parallel to the body of the vertebra. Only the most superior and inferior vertebrae have dis¬ tinct spinous processes, and these have anterior as well as posterior ones. The middle ones have before two crests, which form a half-canal, and behind a tubercle, often bifid, or, when they are elongated, two rough lines. The atlas, which is articulated with the occipital bone by a single facette, has the shape of a minute ring. As the neck of birds is movable, the back is fixed. The Back, spinous processes of these vertebrae are in mutual contact, and they are connected by strong ligaments. Most of these processes are generally consolidated into a single continuous crest, extending along the whole back. The extremities of the transverse processes terminate in two apices, one directed forwards, the other backwards; and occasionally they are consolidated into a continuous mass like the spinous. That this arrangement is requisite for the trunk to remain fixed during the violent motions which take place in flying, is rendered probable by the fact, that in birds which do not fly, as the ostrich and cassowary, the spinal column retains its mobility. The last dorsal vertebrae are often placed on the crest of the iliac bones, and they are then united, as the lumbar, on the large piece of the iliac bones, from which it re¬ sults that the number of vertebrae can often be estimated in no other mode than by that of the holes of the nerves which issue from the chord. The caudal vertebrae are most numerous in the species Caudal which move the tail with most energy; for instance, the vertebra:, magpie and swallow. They have spinous processes be¬ low as well as above, and very long transverse processes. The last of all, to which the pinions are attached, is long¬ est, and has the shape of a ploughshare or a compressed quoit. In the cassowary, which has no visible tail, the last bone is conical; in the peacock, on the contrary it has the shape of an oval plate, situate horizontally. It was early observed by the original zoologist and tra- Cranium, veller Pierre Belon, that the crania of birds were void of sutures; and that in a few only were these lines of dis¬ tinction into separate bones recognised. The explanation of this peculiarity is found in the history of the ossifica¬ tion of the head in young birds, which shows that the cranium consists at that period of separate bones, corre¬ sponding in number and situation to those of quadrupeds. Thus, there are two frontal bones, which are continued forwards to form the vault of the orbits ; two small parie¬ tal bones behind the frontal; a temporal bone on each side of the scull; a sphenoid united to the occipital, even in subjects in which the other sutures are distinct; or a spheno-occipital bone, which is early united with the tem¬ poral. These sutures, however, are distinctly seen only in > ANATOMY. Compara¬ tive Anatomy. 85 young birds and those recently hatched ; for the bones two external ones, which corresnnnH m „ are very early united, and in the adult bird the cranial arches of the Mammalia and whirh o h Zyg]0mJtlC sutures are invanably obliterated. Thus, in the domestic are articulated to the quadrangular bone which moves on fowl and turkey the scull is one piece ; and the only trace the temporal before the eir Th« * " • wmcft ™oves on of suture that remains is a linear depression in the mid- which have been already stated tn ° inter™edialf ones> die of the frontal bone, indicating the original formation rygoid processes,andwhkh are paralHare^lac^d benla'th m ^ l'alves- In rece,"tly bird, also, the the septum of the orbits, and ale articulated by the“ nos tenor extremities with a small bone, variable in shape but named omoid by Herissant, which is also articulated with the quadrilateral. From this arrangement results a singular species of broken lever, not dissimilar to the parallel joint of the piston and lever of the steam-eno-ine and the effect of which is, that whenever the lower5jaw is depressed by its proper muscles, it necessarily causes sphenoid is separated from the occipital bone by a trans¬ verse suture, extending from the one ear to the other. The occipital bone is at the same time a ring, consisting of four parts ; a superior, two lateral, and an inferior which is small. The sphenoid, which forms the greater part of the base of the cranium, is nearly trilateral, with a small anterior process, to which the palatine arches are If has no pterygoid processes, and does not the quadrilateral bo^ne^ p rform’a si ghrSUyTo8 itenor aperture of the nostr s. The lem- iioo ,„ ...u:„u e s "■ rotatory mo- Facial bones. articulated. ^ 7 touch the posterior aperture of the nostrils. The tem poral bone, though void of zygomatic process, has a pointed style, which contributes to form the posterior margin of the orbit. The frontal bone, after covering part of the cranium, is continued forwards in a broad, thin plate, which forms the vault of the orbits, while these ca¬ vities are separated by a thin vertical bony plate which descends at right angles from the frontal bone, and is con¬ nected behind with the sphenoid. The long eminences observed on the heads of the cassowary, curlew, pintado, and some species of hocco, are produced from this supra¬ orbital part of the frontal bone ; and their interior, which consists of loose diploe, communicates with that of the same bone. I he face in birds is rarely so firmly consolidated as the cranium. It is composed of two lacrymal bones, forming the anterior margins of the orbits, and united on the me¬ sial plane; two nasal bones anterior to the lacrymal; two bones corresponding to the superior maxillary, and form¬ ing the external lateral parts of the upper half of the bill; two inter-maxillary bones ; two anterior palate bones, cor¬ responding to those of the Mammalia ; two posterior pa¬ late bones corresponding to the pterygoid processes of the tion, m consequence of which, by means of the omoid bone, the upper jaw is at the same time elevated on the elastic plates; and as soon as the lower jaw is raised, the elasticity of these plates forces down the superior one. The upper jaw is immovable in a few instances only, and of these the calao or rhinoceros bird is one. The breast bone (sternum) is a trilateral, boat-shaped Sternum bone, concave internally, convex with a middle longi-or breast, tudinal crest externally, with the base of the trianglebone' above, and the apex, which is also incurvated backwards, below. The middle longitudinal crest, which is occa¬ sionally named the keel (carina), is shaped something like a spherical triangle, with the broadest side above, the base before, and the apex behind; and its prominence forms large spaces on each side for the attachment of the pectoral and other muscles used in flight. In the male wild swan (anas cygnus), in some species of curlew, in the crane, and in the guinea-fowl, this crest forms a cavi¬ ty for the reception of the windpipe. In the ostrich and cassowary, which do not fly, the sternum is void of crest, and is merely arched strongly. The ribs, which rarely exceed 10 pairs, may be distin-The ribs, guished into sterno-vertebral and vertebral. Though the , .. , . a 1 y ~ r—w.v, guioncu iulu ateuiu-vtirieurai ana verteorai. inouari the of nn°ld ; and v1?! kT JaWi a Parfboloid bone’ consisting latter are generally before, they are sometimes also be- of two ram* united before, where thev are covered hv the hind Tho nQv-i-QLroi : . i- I’he quad- lateral kone. of two rami united before, where they are covered by the horn of the lower half of the bill. Besides these, there is in the whole class an irregular-shaped bone, common to the cranium and lower jaw, and connecting these two together. This bone, which has been rather improperly named the 1 1 j , A r v sLcuiu-Lusua cartilages or tne iviammalia by umtino- square, quadrangular, or quadrilateral bone (os quadratum), the rib to the sternum. The ribs of birds, however are COIlSlStS of hnriv with r»nrvilin^Qr hz-Jl/Avnr i• . • • i v v . - . ? hind. The vertebral end terminates in two diverging pro¬ cesses, one of which is articulated with the vertebral body, the other with the transverse process. The sternal extre¬ mity consists of a bony process, which performs the part of the sterno-costal cartilages of the Mammalia by uniting laxillary nies. consists of a body with curvilinear hollow margins, termi nating in two elevated and rather pointed processes, one of which is connected with the cavity named tympanum, while the other, projecting into the orbit, affords attach¬ ment to several muscles. The anomalous character of this bone has perplexed several of the most distinguished zootomists; and while Geoffroy gives it the name of os Tympano-styloidewn, Spix considers it analogous to the annular process of the temporal bone, which in the human . ^ »» V, * J ClJl C further distinguished by presenting near their middle a flat long process, projecting from the rib backwards at an acute angle, and resting on the rib immediately below, so that each rib is supported not only on the vertebrae and sternum, or the vertebrae alone, but on the next rib below. These processes are obliterated in the lower ribs. The coxal bones constitute one piece wfith the sacrum Basin or and lumbar vertebrae. The ischial portion is united withPelvis- the sacrum, and the ischiatic notch is converted into a r A. • 1 .T All. XlU.llia.lI LUC 5 he'^LTXi.iM CarUS regfdS 11 Is, repr-Se uting I'0'6' The part which corresponds to the os piibis of the aiirt h b ?rsar eresembance'nshape is not consolidated before so af to form a ‘ one of its connections. .cvmrJvfrcic ™ _ and in one of its connections. Both maxillce are void of teeth; but the hard, horny matter of the bill covering the margins and extremities of each jaw, and constituting the mandibles (mandibula), is manifestly constructed to perform for Birds what teeth do for the Mammalia. But the most remarkable pe¬ culiarity of the facial bones of this class is, that the . ~ l/W 1W11U a symphysis, but proceeding directly backwards, terminates in a styloid process, variable in length and slenderness. The only exception to this mode of structure occurs in the ostrich, in which the pubal bones are united below. The infra-pubal or oval hole is present in the whole class not¬ withstanding. It is worthy of remark, however, that in unner Gw nflmDo T young birds this and the ischial aperture are still notches, ritv V ms=S, f m°reff °r m°tl0n' In.the maj°- in consequence of the deficient ossificatiofi of the parts, to the crant?m ! HlS 18 eSJte,d. by theJaw being united The direction of the pelvis in birds is nearly that of plates • but in tli ^ means 0 lm’ flexible, elastic, bony the spine, that is, obliquely backwards, and deviating but d sthmt mV Parrotlfamdy the upper jaw is entirely little from the horizontal line. The incp ^0nnecte by a proper articulation. The wings or thoracic extremities are connected to the divided intn A 6 atine. surface of the upper jaw is trunk by three bones, the collar-bone or clavicle, the sra-Collar- lancies, which diverge backwards. The pula, and the bifurcated bone. The collar-bones, which bone. 86 ANATOMY. Compara- are straight, strong, and cylindrical, are articulated by a tive large head with the anterior and lateral part of the ster- Anatomy. num> in which its motion is rather limited. It forms be Shoulder- blade. Furcula. fore and laterally two short processes, one anterior-infe¬ rior and internal, articulated with the bifurcated bone; the other posterior-superior and external, uniting with the scapula, and forming a cavity, in which the head of the humerus is lodged. The scapula is a long bone, flattened, but narrow, and slightly incurvated, with the convex side turned towards the spine, to which it is nearly parallel in position. The head or anterior extremity is thick and extensive, oblique from before backwards, and is articulated behind with the clavicle, before with the humerus. The free extremity is thin, flattened, and sharp. The whole bone is not dissi¬ milar in shape to a scimitar. Bifurcated Besides these, which Birds possess in common with the bone, or Mammalia, we find an azygous bone, situate on the mesial plane, denominated in ordinary language the .Mem/ thought, and, from its shape, the fork-like or bifurcated bone. It consists of two long, rounded, converging branches, united at an acute angle, and forming a broad process, flat in the vertical direction, and by which it is articulated to the anterior extremity of the crest or carinated part of the breast-bone. To the posterior or free extremities of the divergent branches are articulated the humeral ends of the collar-bones, which are thus enabled to sustain the violent motions of the humerus during flight. The branches of the bifurcated bone are separate in the os¬ trich, and each is united with the clavicle and scapula of the same side, so that the three bones form only one, much flattened, and with a hole towards the sternal ex¬ tremity. In the cassowary the bifurcated bone is re¬ duced to a mere rudimental process at the inner margin of the head of the clavicle. From these facts it results, that the bifurcated bone is particularly useful in the ener¬ getic and continued efforts of the wings in flight, and not only serves to keep the clavicles apart, but, by lengthen¬ ing the distance between the collar-bones and sternum, enables the animal to use a longer lever. It is freest, strongest, and most elastic in the birds which fly best. In birds which do not fly, and which use the wings mere¬ ly to sustain the equilibrium, as the ostrich and casso¬ wary, it is reduced to almost nothing, or it is in such a rudimental and imperfect form, that it cannot keep the collar-bones apart. The bones of the thoracic extremities, or those of the wings, correspond in general to those of the Mammalia. They consist of a single cylindrical humerus, articulated with the scapula and collar-bone above, two bones of the fore wing corresponding to the ulna and radius, two bones of the carpus, two of the metacarpus, consolidated by their extremities, one styloid bone as a thumb, a long finger con¬ sisting of two phalanges, and a short one consisting of one. The thumb supports the bastard pinions, the large finger and metacarpus the primaries, while the small one, which is covered by the skin, is destitute. In several of the web¬ footed divers, for instance the duck and penguin (alca im- pennis and spheniscus), these bones are flattened like thin plates. In the pelvic extremities the thigh-bone is provided with one trochanter only, is shorter than that of the leg, and is almost invariably straight; and is arched only in the cormorant, duck, and dobchick. In the ostrich its dia¬ meter is about four times that of the humerus. The tibia differs from that of the Mammalia chiefly at its lower extremity. While the fibula adheres to it like a slender appendage as far as the middle, the tarsal extremity ter¬ minates in two trochlear condyles, with an intermediate pulley-like groove. The tarsus and metatarsus are repre¬ sented by a single bone of considerable length, and the Compara. head or tibial end of which consists of a middle piomi- . nence and two lateral depressions, and which, therefore, moves in cardinal opposition, but does not admit of exten¬ sion beyond the straight line. Though variable in pro¬ portion to the length in different orders, this bone is very long in the order Grall.® (Grallatores). It termi¬ nates below in 3 pulley-shaped processes, to which are attached the bones of the 3 anterior toes, with an inter¬ nal margin for that of the great toe. In the ostiich there are 2 processes only, corresponding to the two toes. In the penguin tribe, however, the tarsus and metatarsus con¬ sist of 3 bones, separate from each other in the middle, but united at the tibial and digital extremities. To the tarso-metatarsal bone of the cock, and others of the Galli¬ naceous tribe, is attached the spur, a conical pointed ex¬ crescence of hard horny matter. Thoracic extremi¬ ties. Pelvic extremi¬ ties. SECT. III.—OSTEOLOGY OF THE REPTILES. The number of vertebrae, and all the other attributes of the spinal column, vary more in this class than in all the others. In the Cheloniad or Tortoise family there are 7 cer-Vertebra', vical, 8 dorsal, connected with the shell in an immovable piece, so as to have neither processes nor articular facettes; from 3 to 5 lumbar and sacral, consolidated in like manner ; and about 20 caudal or coccygeal. (Plate XXXIV. fig. 5.) In the Saurial or Lizard tribe, the number 7 predomi¬ nates in the cervical, being that of the crocodile and most lizards. In several, however, there are 8, as in two of the monitor genus, the American safeguard, the lizard of Fontainebleau, the dragon, the iguana, the anolis, and the gecko and seine; and in a few, as the Nilotic monitor, and an undetermined species of monitor, they amount to 9. In the chameleon there are only 5 cervical vertebrae. Here, however, a singular peculiarity is observed. Instead of the cervical vertebrae being, as in the Mammalia, distinguished by being unconnected with ribs, to those, from the third to the seventh inclusive, short ribs, un¬ connected with the sternum, are attached. The atlas and axis, therefore, alone are proper cervical vertebrae; but the general analogy is observed in the cervical ribs being exceedingly short and almost rudimental. The dorsal vary from 11, which is that of the crocodile and iguana, to 29 and 30, which are the numbers in the New Holland seine and Nilotic monitor. In the American safeguard, cordy- lus, stellio, crested basilisk, dragon, guana, and great ano¬ lis, they are 16 ; in the chameleon, black safeguard, and ameiva, 17 ; in the tupinambis, spotted gecko, and golden seine, 18; in the green lizard and spotted guana {poly- chrus) 19; in the Fontainebleau and gray lizard 20; 21 in the Levant seine and undetermined monitor; and 22 in the Java and New Holland monitor. The Batraciioid or Ranine reptiles are void of ribs, and it is impossible therefore to distinguish the first three orders of vertebrae from each other. In general, however, there are from the nape to the pelvis 8 vertebrae, all provid¬ ed with long transverse processes, and which are longest in the last. The sacrum is represented by a long flattened but pointed bone, without coccyx. In the Surinam toad (rana pipa) the last vertebra is consolidated with this bone ; and the transverse processes of the second and third vertebrae are so much larger than the others, that they resemble ru¬ dimental ribs. In the Salamander family there are from the head to the sacrum 14 vertebrae, all alike in shape ex¬ cept the first, which receives the occipital bone, and the last, which is articulated with the sacrum. These two are distinguished by wanting rudimental ribs, which are small elongated bones, movable, and articulated with the trans- ANATOMY. Compara¬ tive Anatomy. 87 ranium. verse processes, which are directed backwards. The arti- Still more manifest is this arrangement in the Ranine Compara. cular processes are large and imbricated, the posterior or Bathachoid and Serpentine or Ophidial Rentiles tile , resting on the anterior, so as to resist the motion of the In the former, as exemplified in the froir the occinital hone Anatomy. spine backwards. The sacrum consists of one vertebra which forms the posterior cranial vertebra consist* nffmw ^ only, but the coccyx or tail is composed of 27. pieces, and has two articular processes The middle era In the Serpentine tribe the vertebrae may be said to nial vertebra is represented by the parietal bones above attain the most extensive numerical developement. With and the posterior part of the sphenoid below while he the exception of the head and rudimental ribs, they con- tween it and the occipital or posterior is contained the’ stitute the whole skeleton. (Fig. 3.) From the head to the temporal as the organ of hearing. The third or anterior tail their shape is the same, and may be distinguished into cranial vertebra is represented by the anterior part of body, articular and transverse spinous processes. In some the sphenoid bone below and the two narrow frontal species, for instance the boa, the spinous processes of the bones above. The face, which mav be regarded as the back are so much separated as to allow mutual motion to a organ of the senses, is elongated anterior&to the head considerable extent. In others, conversely, for instance somewhat after the manner of the Cheeoniad familv • the rattlesnake, these processes are so long and broad as while an approximation to the Birds is indicated in the' to touch each other, while the oblique processes, which articulation of the lower jaw, which is connected to the foim their bases, are imbricated over each other. In con- head by the intervention of a quadrilateral bone. In the Serpentine family, the cranium of which is very similar in other respects, the most remarkable deviation is in the want of ethmoid bone. The lower jaw is con¬ nected to the cranium by an intermediate bone, corre¬ sponding to the quadrilateral, but of an oblong shape, and something like a collar-bone. The chest of the Reptile class varies much in the Chest, mode of formation. While true ribs are recognised in the Saurial family only, the Batrachoid reptiles have a sternum without ribs, the Serpentine ribs without ster¬ num, and the Cheloniad ribs united into the dorsal shell, and a sternum expanded into the abdominal one. In the Saurial family the ribs correspond in number Ribs, to that of the costal vertebrae already mentioned, that is, 12 in the crocodile and iguana, two of which are not con¬ nected to the sternum, 17 in the chameleon, 18 in the tupinambis, and 27 in the monitor. The Saurial rep¬ tiles, however, are peculiar in having from 1 to 6 ribs at- J ^ sequence of this arrangement the motion of the spine is limited behind, but more extensive on the ventral sur¬ face. The vertebral bodies, which move easily on each other, are provided with a sharp spine directed towards the tail, which somewhat limits motion in this direction. The first vertebra differs from those of the rest of the body in supporting short or rudimental ribs ; there are therefore no cervical vertebrae and no proper neck in the serpent family. The caudal vertebrae are distinguished by not supporting ribs, and by their spines both dorsal and ventral being double, and forming two rows of tubercles. The articulation of the bodies of these vertebrae is pecu¬ liar. On the anterior part of the body is a round hemi¬ spherical tubercle, while the posterior presents a corre¬ sponding cavity, so that each vertebra forms a cup and ball joint with the following one. The number of costal vertebrae varies from 32, which is that of the blind worm (Anguis fragilis), to 204 in the 1 1 7 7 . > \ J7 , 7 . ’ AAA Having 11UU1 A LU W I1US U [- ringed snake (Coluber natmx), 244 in the snake, and 252 in tached to the cervical vertebrae, and the opposite ends of the Boa constrictor, .and which 1 S TTO I'll ITS f" O O’FOG F tirll I /■•I'l o y*w r\4- ■w•»-» 4- /-x 4- i-v 4-1-v ^ rT,l_ _ 1*1 the Boa constrictor, and which is perhaps the greatest known number. Of intermediate numbers, the Amphisbcena has 54, the viper (Coluber berus) has 139, the rattlesnake 175, and the cobra di capello 192. The caudal vertebrae vary in number from 7, which is that of the Amphisbcena, to 112, which is that of the Coluber natrix. Of interme¬ diate numbers, the blind worm has 17, the rattlesnake 26, the boa 52, the viper 55, and the cobra 63; from which it appears that the number of the caudal is not in pro¬ portion to that of the costal vertebrae. Of the heads of the Cheloniads, the most remarkable characters are, that the facial line is horizontal, and quite continuous with the cranial line; that the orbits, though which are not connected to the sternum. These, which have been named cervical ribs, form a transition to the rudimental ribs of the Serpentine family, which are larger in the neck than elsewhere. The sternum of the crocodile consists of two parts,—an anterior or thoracic, which is osseous, supporting the two collar-bones,—and a posterior or abdominal, which is cartilaginous, and extends to the pubis, and furnishing to the abdominal parietes eight cylindrical cartilages. In the East India crocodile it appears that these lateral processes are converted into a single broad piece of cartilage on each side. (Fig. 4.) The ribs of the Cheloniad family are represented by Dorsal and waaaaaha A.AAV-, a a aca u A» i c uiuiL», uiuugu the dorsal shell, which consists of eight broad incurvatedsterno-ab- complete without, are continuous behind with the temporal plates, identified behind with the dorsal vertebiTe, and^0111^! fossae ; that the parietal and occipital bones are compressed terminating before in the margin of the shell, and which laterally, wlnle the latter ^terminates above in a sharp are doubtless genuine ribs. In the ordinary land-tortoise (Testudo Grceca) these are seen in the shape of elevated bony ridges, proceeding from the head of each rib in a trans¬ verse concave bend to the margin of the dorsal shell. On each side of these ridges the bone is depressed, and is united at its lowest point by a genuine suture with the ad- spine, projecting behind. The occipito-parietal and occi- pito-temporal sutures are distinct. The cranial cavity is small compared with the volume of the scull. These characters are not less remarkable in the Saurial or Lacertine Reptiles. The cranium of a crocodile mea- . IQ \ A r • 7. ^1, f'vsxwi, KJJ a. OULU1C Willi LllCctU" suring trom 13 to 14 leet is scarcely capacious enough to joining ones. These sutures, however, are not continuous admit- tl 1 thlimK • Ond ( 11V 71 n 11 %-v-* 4-a-x At 4-1-* u n „ i.* _ ? x1_ C* if 1 1 •- i t -at « .. admit the thumb; and Cuvier estimates the area of the cranial section, which is oblong, at about of that of the whole head. In these animals, indeed, the bones of the superior and inferior jaws are so much prolonged, and oc¬ cupy so large a proportion of the head, that small space with those of the sterno-abdominal shell, but meet it in the intermediate points. (Fig. 5.) The sterno-abdominal shell consists, in like manner, of several transverse pieces consolidated into one. The ordinary number is eight on each side of the mesial plane, and a ninth azygous, gene- • 1 -Pf 1' 1-1 * • ' • £ dAV-4V-' IaIIC liicold.! lyiclllt.} CtilLi cl Hill is c or the proper cranial cavity, which indeed is an rally placed in the centre of the shell. In a specimen, immediate continuation of the vertebral. In these ani- however, of the tabular tortoise (Testudo tabulata), in our ma s, a so, t ic anatomist can trace, much more distinctly possession, the number of the sterno-abdominal pieces is lan m t e more perfect, the resemblance between the 11, of which 8 are in pairs, united on the mesial line from crania )ones and the vertebral. In the Cheloniads, and before backwards, and 3 azygous at the posterior tip of the aurial especially, the occipital bone is very distinctly a shell. In young animals it is easy to recognise the unions cep in ic veitebra. 0f these constituent bones, which consist of sutures ex- 88 Compara- tive Anatomy- ANATOMY. Thoracic- extremi¬ ties. actly similar to those of the cranium in the Mammalia. So feeble is the union, that it often happens that the ab¬ dominal shell especially separates at the lines of junction, in the attempt to detach it from the dorsal. The Batrachoid Reptiles, though void of ribs, are provided with a sternum, which before is a cartilaginous process, terminating on a disc placed below the larynx, where it receives the collar-hones, and forms behind a broad plate placed below the abdomen, and giving attach¬ ment to the muscles. In the Salamander tribe, which are without sternum, the ribs consist of twelve pair of small rudimental processes, articulated with the vertebrae, but admitting of very limited motion. Lastly, in the Serpentine family, though there is no sternum, the upper vertebrae are provided with costal processes, quite rudimental. The great number of these costal rudiments, amounting in the rattlesnake to 175, in the cobra di capello to 192, in the coluber natrix to 204, and in the boa constrictor to 252, and the freedom of their anterior extremities, enable the animals of this tribe, which are destitute of locomotive members, thoracic or abdominal, to employ the spinal column and the ribs as organs of progressive motion. On this point the reader will find some interesting observations by Sir Everard Home {Phil. Trans. 1812, p. 163). In the region of the neck, where the ribs acquire peculiar length, they are employed in erecting that region, and producing the ex¬ pansive swelling peculiar to this tribe of animals. . It is an important link in the same series of facts, that in the animal absurdly named the flying lizard {draco volans), the five posterior ribs are recurvated and elongated to form the bony skeleton of the membranous sails by which the ani¬ mal supports itself in its desultory flight from tree to tree. It is in the Saurial family that the locomotive extre¬ mities of Reptiles ought first to be studied. In tkese we find an elongated scapula without spine, and one short flat bone, constituting the clavicle, united to the sternum. In the iguana and chameleon this bone is broad and nearly quadrilateral, while in the tupinambis it is large and oval¬ shaped, with its greatest length from before backwards, and with two unossified points. In the Ranine tribe, while the scapula consists of two articulated pieces, the upper towards the spine, each shoulder is provided with two collar-bones attached to the two extremities of the sternum, and the two anterior of which correspond to the bifurcated bone of birds. The sternum, collar-bone, and first part of the scapula, form one piece. In the salamander, in which the same conso- ! lidation is observed, the scapular portion is most distinct and directed to the spine, while of the clavicular portion | the part connected to the sternum stretches below the ; chest, but, without uniting with that of the opposite side, the right glides over the left,—an arrangement which fa- I cilitates the dilatation of the chest during inspiration. A nearer approach still to the bifurcated bone than is «een in the Ranine may be recognised in the Cheloni ad family. In these animals three bones are united to form the humeral cavity. The first is a flat, trilateral bone, situate below the abdominal and thoracic viscera, close to the abdominal shell, and which, notwithstanding its situa¬ tion, is evidently the scapula. The second is a bone about the same length, flat, and like the feather of an oar at one extremity, which is free, round in the middle, and flatten¬ ed in: the opposite direction at the other end, which is firmly united at a right angle to a long slender cylindrical bone! At the angle of union of these two bones is part of the glenoid cavity, which is complete in the small end of the scapula. The first of the two bones is the collar¬ bone proper; the second is the lateral branch of the bone, which forms the bifurcated, and which is occasionally united with its fellow. (Plate XXXIV. fig. 5.) The abdo- Compara. minal shell we have already stated to represent the ster- num or breast-bone. „ .. The humerus in the Saurial and Cheloniad family is arched and incurvated in a serpentine direction. It is articulated with a radius and ulna, which are succeeded by three rows of carpal bones, one row of four metacarpal bones and digital phalanges, varying in number in differ¬ ent qenera. In the skeleton of a fossil animal belonging to the Saurial tribe, originally delineated by Collim, and Fossil ske. afterwards by Cuvier, and named by him the Pterodac-^™*} tyle or Wingtoe {Pterodactylus, Ossemens Possiles, tome re.)tjje v.), the metacarpal bone and phalanges of the index are prolonged to about twenty times the ordinary length, for the purpose, apparently, of giving attachment to the mem¬ branous web by which the animal occasionally elevated it¬ self into the atmosphere. This animal, which, like the dra¬ gon {draco volans) of modern times, must have combined the contradictory characters of a flying reptile, may be re¬ garded as forming the link between the Reptiles and Birds, as the Ichthyosaurus does between Reptiles and FISH ES« In the pelvis of the Cheloniad family it is remarkable Pelvis, that the pubal and iliac bones appear to change places. Thus the ilium on each side is a narrow bone proceeding backwards to the sacral part of the spine, which is re¬ ceived between its posterior aperture; while theap¬ pears in the shape of a broad, trilateral, flat bone, uniting before with its fellow on the mesial plane, behind with the ilium, and below with a flat, thin, quadrilateral bone, cor¬ responding to the ischium, with which it forms the oval aperture. The inner of these three bones presents, as usual, the cotyloid cavity. It is further to be observed, that the two iliac bones, and consequently the whole pel¬ vis, are movable on the vertebral column. (Plate XXXIV. fig. 5.) In the Saurial Reptiles the pelvic bones are arranged Pelvic ex- and shaped nearly as in the Cheloniad. In the Ranine tremities. the iliac bones are much elongated, and the pubal and ischial are consolidated into one piece> the symphysis of which forms a rounded crest. The femur is short, thick, and incurvated sinuously, with the convexity before towards the tibial end, and the con¬ cavity towards the pelvic. Trochanters, though present in the Cheloniad, are wanting in the Saurial and Ra¬ nine Reptiles. In the leg we find both tibia Jibula distinct, and of nearly equal size, in the Cheloniad and Saurial family, but conjoined in the Ranine family. The tarsus consists of five bones, and sustains four or five metatarsal ones, on which are supported three rows of phalanges. The metatarsal bones, which vary in length, are longest in the crocodile and others of the Lacertine tribe. In the Ranine, again, the astragalus and calca- neum are the bones of greatest proportional length. The anatomical characters now enumerated are proper to the skeletons of Reptiles at present existing on the surface of the earth or in its waters ; and in these we find a gradual transition from the Saurial and Cheloniad, by means of the Serpentine, to the finny inhabitants of the ocean. Even the Batrachoid Reptiles, in the early period of their existence while tadpoles, we shall have occasion to see, approach to the Fishes ; and in one sin¬ gular genus, if not two, the Proteus anguinus and Siren Lacertina, the characters of the Reptile are combined with those of the Fish, in having at once lungs or internal respiratory cells, and gills or external ciliated branchiae. The transition thus indicated is still more strongly de¬ monstrated in the osteological characters of two Genera of animals now extinct, so far as is yet known,—the Ich¬ thyosaurus and the Plesiosaurus. ANATOMY. Compara- From the specimens of the Ichthyosaurus hitherto dis- tivc covered, it appears that the number of vertebra? varies from 80 to 90 or more; in one entire specimen they amounted Osteoiorri- t0 104, (Conybeare and De la Beche); that they are flat- cal pecuh- tened, with the transverse diameter greater than the longi- arities of tudinal, and the two articulating surfaces of the bodies the Ich- calycoid or cup-shaped as in Fishes. Though the annular thyosauruspart js distinct from the body, it is united to its sides. The spinous processes, which are long and prominent, form a continuous ridge above the spine, and are connected to each other by a process from the front of the one spine, which is inserted into a pit in the back of the other. In¬ stead of proper transverse process, a certain number of the vertebrae are provided with two tubercles on each side of the body, of which the superior, convex, is articu¬ lated to the tubercle of the rib, while the other, which is concave, receives the head. In the inferior part of the vertebral column, these two tubercles, after approximat¬ ing, are eventually identified into one. The ribs, which are numerous, and extend from the occiput to the pelvis, are slender and trilateral in shape, bifurcated above, and attached to the vertebrae by a head and tubercle. In the perfect specimen of Mr de la Beche they amount to 31, and of these 17 appear to be cervical or anterior false ribs, with single tubercles; thus affording another mark of resemblance to the Saurial family in osteological characters. The bones of the head, distinguished by the extraordi¬ nary size of the orbit, are similar to those of the Saurial Reptiles. The sternum, collar-bone, and scapula, though also similar to those of this family, bear a much closer re¬ semblance to the figure of these parts in the Echidna and Ornithorhyncus. The humerus is short, thick, and sinuat- ed; the bones of the fore arm flat, and probably constitut¬ ing part of the fore or thoracic fin. The Carpus consists of three rows, the first containing three bones, the other two, four each. These are followed by five or six rows of flattened, irregularly cuboidal bones, gradually diminishing in size and number to the tips, and which represent at once the metacarpus and phalanges of the fore paw, used appa¬ rently chiefly as a fin or paddle. The pelvic extremities appear to have been less strong and perfectly construct¬ ed than the thoracic. The femur is smaller and shorter than the humerus ; the tibia and fibula are flattened like the idna and radius ; the tarsus consists of two rows only, the first containing three, and the second five bones ; and this in like manner terminates in five ranges of flattened bones, gradually diminishing in size, and which represent the metatarsus and metatarsal phalanges of the hind paw or paddle. From the specimens hitherto discovered of the Plesiosau¬ rus, it appears that the total number of vertebrae amounts to 90, of which 35 appear to be cervical, while the other 55 are dorsal and caudal, the regions of which are propor¬ tionally short. The head of this animal also is small and compressed, nor has it the large orbit of the Ichthyosau¬ rus. Each rib consists of a vertebral and sternal portion, united at an obtuse angle, the former articulated by a single head to the transverse process, and the latter con¬ nected with its fellow by a transverse slip, so that the lower or abdominal ribs appear to have surrounded the abdomen with a complete cincture. The anterior part of the chest is occupied by two trilateral bones uniting in the middle, which, from t.hpir r,nnnp/->f-!nn uritR 89 num and the transverse bone the clavicles; and it is Compara- orthy of remark, that not only this bone, but the middle tive piece, closely resembles in figure and disposition those 0f Anatom-v- the Echidna and Ornithorhyncus. The pelvis consists of^^ three bones, a vertebra or superior, corresponding to the ilium narrow and slightly incurvated ; an anterior, ascend¬ ing forwards, and broad, separating the pubis; and a pos¬ terior, short, forming the ischium. The humerus and femur are longer than in the Ichthyosaurus. There is a very short radius and ulna, and tibia and fibula, articulated with five carpal and tarsal bones; and the rest of both paddles consists of successive rows of flattened but lon£ bones, contracted in the middle, and expanded at the ex¬ tremities, representing the metacarpal and metatarsal di¬ gital phalanges. (Home, Phil. Trans. 1816, 1818, 1819, 1820; De la Beche and Conybeare, Geological Transac¬ tions, vol. v. p. 559 ; and Cuvier, Ossemens Eossiles, vol. v. part ii.) SECT. and Ple¬ siosaurus. the middle, which, from their connection with the scapula, are believed to be the coracoid bones; and above these is a transverse piece, with a middle notch and lateral sinuated elevations, which is regarded as the sternum; while the scapula extends on each side like a buttress be¬ tween the two. It is not improbable, nevertheless, that the middle portions named coracoid bones are the ster- vol. m. IV. OSTEOLOGY OF THE FISHES. The Serpentine or Ophiad Reptiles present in their osteological characters an approximative transition to those of Fishes. While in the former order the skeleton is reduced to the spinal column, ribs, and head, in the latter class the spine and head only are left; and in some tribes the transition is still more distinctly marked by the presence of ribs. The vertebra of a fish is distinguished from that of any Vertebra;, other animal by the shape of its body. The cephalic and caudal, or anterior and posterior surfaces, are hollow cup¬ like cones, so that the union of each two vertebrae forms a double conical cavity, united by the base, containing a substance composed of concentric fibro-cartilaginous layers, with intermediate albuminous or gelatinous matter. By this cartilage the vertebral bodies are united; and on this the motions of the spine are effected. This motion, how¬ ever, is chiefly lateral; for the spinous processes are so long, and the articulation so complex, that antero-poste- rior inflection or extension is nearly impracticable. In the cartilaginous fishes, for instance the shark, stur¬ geon, and lamprey, the vertebral bodies form simple tubes, which, from the extreme elasticity of the constituent car- tilage, propel the contained fluid to a considerable dis¬ tance. Thus Sir E. Home saw the fluid projected to the height of four feet from the intervertebral cavities of the shark. {Phil. Trans. 1809.) In this order, also, the spine is infinitely more flexible, and its resilient power, when bent by the muscles, is almost incredible. On each side, also, the vertebrae are excavated, to form a canal for lodging the large blood-vessels. Ihe vertebrae of fishes are numerous, and not easily distinguished into classes. They may, however, be dis¬ tinguished into two, according as the spinous process is above only, or above and below at once. Those with the dorsal spine only are denominated dorsal or abdominal verte¬ bra, and have commonly at the sides transverse processes for the attachment of the ribs. Those with the dorsal and ventral spines are distinguished as the caudal verte¬ bra. Ihe last caudal vertebra is generally trilateral, flat¬ tened in the vertical direction; and its tip is marked with articular pits, which indicate the attachment of the small elongated bones which sustain the caudal fins. Ihe number of vertebrae varies. In the uranoscopus or star-gazer there are only 25, in the balista 17, and in the four-spined trunk-fish (ostracioii) only 13; while in the sturgeon the number is 84, in the eel 115, and in the shark 207. Though Fishes have no chest, and require none, since their respiratory organs are gills, all of them are not void of ribs. The ray, shark, syngnathus, tetraodon, diodon, cy~ M 90 ANATOMY. Compara- chpterus, Jlstularia, &c. have indeed no vestige of rib. tive But in the sturgeon, balista, eel, uranoscopus, pleuronectes. Anatomy. sea-wolf, and dory, they are in the shape of short rudi- mental processes ; in the trigla and loricaria their sides are horizontal; in the perch, carp, pike, and chetodon, they encompass nearly the whole upper region of the abdomi¬ nal cavity ; and, lastly, in the silver-fish (zeus vomer), the herring, rhomboidal salmon, &c. they are united to a sternum. In the little animal named sea-horse (syngna- thus hippocampus), several series of osseous tubercles of the skin, surrounding the body like belts, are supposed to represent false r'bs. The sternum is limited to a small number of Fishes. Besides those already mentioned, in the dory there is a series of minute flat bones disseminat¬ ed along the lower edge of the belly, which is supposed to represent a rudimental sternum. In size and number the ribs vary, though in the silurus, carp, and chetodon they are of largest proportional size ; in the herring they are as fine as hairs. The head. The head in the finny tribes is more an object of zoolo- Cramum. gical than anatomical description. The chief points to be remarked are, that the cranium forms but a small part of the head; that the orbits are separated by a septum, some¬ times membranous, occasionally, as in the wolf-fish, bony ; and that there is on each side a large movable bone, cor¬ responding to the quadrilateral of Birds, not square, however, but oblong, which supports not only the lower jaw and palatine arches, but the gill-cover. In the car¬ tilaginous fishes the sutures are early obliterated, and the cranium consists of an inseparable mass of cartilage. In the bony fishes the cranium is separable into numerous pieces, and in the perch they amount to 80. In the cra¬ nium of fishes the anatomist recognises more distinctly than in the superior orders the formation according to the vertebral type. Small in proportion to the whole head, the cranium appears like a direct continuation of the ver¬ tebral column. In the osseous division of the class es¬ pecially, the cranium may be distinguished into the occi¬ pital or posterior vertebra, the spheno-parietal or middle, and the frontal or facial vertebra. The cavity thus formed is very small; yet small as it is, it is not exactly filled by the brain, between which and the bones there is inter¬ posed a pellucid fluid, contained in fine cellular tissue. The cranium of the osseous fishes also is widest between the ears, because the organ of hearing is contained within its cavity with the brain. In the cartilaginous it is quite different. i.oa»ino- Though Fishes are destitute of extremities similar to live mem- those possessed by the other three classes of the Verte- bersorfins. BRATa, they are not, however, without locomotive mem¬ bers. The thoracic extremities are represented by tbe pectoral fins, and the pelvic by the ventral. In short, it may be said that the bones of the thoracic and abdomi¬ nal extremities are converted into osseous rays in the finny tribes. Pectoral In the Ray genus, in which the wing-like disposition of fins. the pectoral fins gives the body a rhomboidal shape, they consist of numerous radiating cartilaginous lines, all at¬ tached to a cartilage parallel to the spine, divisible into two or three others, and articulated above to another ad¬ herent to the spine. Below there is a strong transverse bar common to the cartilages of both fins, and separat¬ ing at once the sternum and clavicle. This transverse bar is also seen in the shark tribe; but their pectoral fins, which are much smaller, are not articulated with the spine. In the osseous fishes, and in many others usually re¬ ferred to the cartilaginous division, e. g. the balista, the pectoral fins are fixed to an osseous belt, which sur¬ rounds the body behind the gills, and which supports the posterior margin of their aperture. This belt consists of Compara. a single bone on each side, articulated to the posterior- tive superior angle of the cranium, and uniting below the^™ny breast with that of the opposite side. This bone, which peclora] may be regarded as a scapula, varies in shape and the^nS4 ano-le which it forms with its fellow in different species. In fishes flattened vertically, the angle of union is acute; in those which are depressed, the angle is so obtuse as to form nearly a straight line. In many fishes, especially those of the order Thoracici, e.g. pleuronectes, coitus, zeus, chetodon, perch, &c., in the small unicorn (Sa/fste), and others, the superior part forms a large spine,, which de¬ scends immediately behind the fin, and to which the ad¬ ductor muscles are attached. This spine, which is mov¬ able, has been improperly named a clavicle. The rays by which the membrane is supported are not directly articulated to this belt, but are connected by a row of minute flat bones, which may be compared to the carpus in the other three classes. When the fiist ray of the pectoral fin, however, is thorny, as in the harness-fish {loricaria), and some species of silurus, it is articulated di¬ rectly with an osseous belt; and it is remarkable that some fishes, as the silurus and stickle-back, have the power of retaining this spinous ray erected against the body as a means of defence. This is effected by a cylindrical tu¬ bercle, on which the spinous ray is articulated by a hoi-, low, bounded before and behind by an elevated process. When the spine is erected, the anterior process, entering a hole in the cylindrical tubercle, is locked in it by the spine revolving slightly on its axis, so that it cannot be inflected unless by the spine revolving in the opposite di¬ rection. The pectoral fins are so long that they answer the pur- Pterygoid pose of wings in several species of trigla, the trigla Ai-pectoral rundo, the flying gurnard {trigla volitans), the springinghns- gurnard {trigla evolans,) in the scorpmna volitans, the tropical flying fish {exoccetus volitans), and some others. Their situation also is liable to vary. In the exoccetus they are near the gills, but in tbe blennius and others they are remote. Lastly, they are totally wanting in a small number only, as the lamprey {petromyzon), the hag-fish {myxine, Lin.; gastrobranchus), the murcena, the eel genus, the sphagobranchus, &c. The abdominal or ventral fins, which correspond to the Abdominal pelvic extremities of the other classes, are so denominated or ventral because in the majority of fishes they are situate below hns- the belly, and nearer the anal outlet than the pectoral. By this circumstance a numerous order are distinguished by tbe name of Abdominal Fishes (Abdominales). In a small number of fishes, comprehending the gadus, blennius, hurtus, callionymus, trachinus, and uranosco¬ pus, the ventral fins are placed under the throat, below the aperture of the gills, and before the pectoral fins. This order is therefore distinguished by the name of Ju- GULARES. In the most numerous order of all, the ventral fins are situate behind and below the pectoral fins. These have therefore been denominated Thoracic Fishes (Phora- cici). The ventral fins consist of two parts—one formed of rays covered by a double membrane, apparent externally, and constituting the proper ventral fin ; the other internal, representing the coxal bones of the pelvis, always support¬ ing the pinna! rays, and often articulated with the bones of the trunk. It is never articulated, however, with the spine, nor does it form an osseous belt round the abdo¬ men. The bones of which it consists are generally flat¬ tened, varying in shape, and in mutual contact by the in¬ ternal margin. In the shark and ray genera only is there a single transverse bone, nearly cylindrical, to the extre- ANATOMY. i)l Compara- mities of which the fins are attached. The direction of dve the pelvic plane to the walls of the abdomen varies ac- Anatomy. cor(]ing to the shape of the body of the fish. In the flat vCntra?^ ^shes th0)' are directed obliquely, and their inner margin gns forms the keel of the belly. In fishes with a broad or cy¬ lindrical belly they form a plane more or less horizontal. In the Jugular and Thoracic Fishes, the pelvic bones are always articulated with the base of the belt which sustains the pectoral fins; and they vary much in shape and situation. In the trachinus, uranoscopus, coitus, sciama, chetodon, and perch, these two bones are united by their inner mar¬ gin. In the cuckoo-gurnard, in which they are united by the posterior tip only of their internal margin, they are broad, flat, and oval. In the sole and flounder genus (pleu- ronectes), in which the fins are attached to their anterior tip, they are united in a quadrangular pyramid, the apex of which is directed backwards and upwards, and the base forwards. In some of the stickle-backs these bones once, and perhaps intermediate between the two, this ab- Compara- breviation is carried perhaps to its greatest possible degree, tive in leaving the articular ends only of the four locomotive Anatom.v- extremities. Lastly this reduction is merely prepara- tory to that exhibited in the whole class of Fishes, in which the three longitudinal bones so conspicuous in the higher classes of animals are completely obliterated, and those representing the hand or forepaw and foot are arti¬ culated directly to the shoulder and pelvic bones. Besides the bones already mentioned as constituting the skeleton, there are observed in the osseous fishes minute bones, generally fork-like in shape, disseminated through all the muscular parts of the body. The purpose of these bones, which, as being totally insulated from the other parts of the skeleton, are denominated ossicula mus¬ culorum, is chiefly to afford points of support; and they are probably to be regarded as rudimental representatives of osseous parts, more completely developed in the higher animals. are altogether separate, and being long, receive in their middle a movable spine, which supplies the place of the ventral fin. In the dory (zeus faber, L.) they are flat and triangular, in mutual contact by their whole surface. In the silver-fish (zeus vomer) they are small and cylindrical. In the whole of the Abdominal order, on the contrary, the pelvic bones are equally unconnected with the bones of the shoulder and with the osseous belt of the pectoral fins, and are confined to the middle-inferior part of the belly, not far from the anus. In general these two bones are separate from each other, and are retained in their si¬ tuation by ligaments. In the carp, in which they are elongated, they touch only by their posterior third. In the herring, in which they are small and approximated, they are continuous with the minute bones of the sternum. In the pike they are broad and trilateral, approximated by their anterior tips, separate behind where the fin is at¬ tached. In the silurus, in which they are united, they form a round and often spinous shield before, while the fins are attached to the exterior-posterior margin. Last¬ ly, in the cuirassier or harness-fish (loricaria), the pelvic bones are united in one piece, the posterior notch of which forms the anal aperture, while the fins are attached to its external margin. The proper fin consists of a certain number of osseous rays, simple or bifid, supported by one or two rows of mi¬ nute bones placed between them and the pelvic bones. On these small bones the constituent rays move, diverging or converging like the rods of a fan, while the whole fin may be inflected or extended by the minute bones moving on the pelvic, so as to adduct or abduct the fin. In the cartilaginous fishes the structure is different. To the tip of each pelvic bone are articulated two principal cartilages, one external, forming a kind of toe with seven or eight joints; the other internal, supporting all the other rays of the fin, which often exceed thirty in number. Analogy or If we suppose these bones, like the minute ones of the nrincM ■ Pectora^ fin> to represent the tarsus of the other three i orgamsa-11 c^asses’ ^ must follow that, in the locomotive extremities, tion. humerus, with the ulna and radius, and the femur, with the tibia and fibula, are obliterated. It is not un¬ important to observe, that the general structure of the Vertebrata tends through various transitions to this ter¬ mination. In the Amphibia the long bones of the extre¬ mities are shortened by removing the diaphysis, and leaving their articulating ends only. In the Cetacea the pelvic extremities are removed altogether. In the Cheloniad and Saurial Reptiles the same long bones of the extre¬ mities are much abridged; and in the Ichthyoid Rep- iiles, now extinct, but sharing by their structure a form of animal existence partaking of the reptile and fish at It is further a curious circumstance, that the skeleton, Violation which is so symmetrical in all the other classes and orders, of the law begins to exhibit a deviation from this first in the skele-°* s.ymrne- ton of the finny tribes. In the Sole genus {Pleuronectes) tlT- this deviation is very conspicuous. Both eyes are placed on the same side of the mesial plane; and the side on which the eyes are placed is broader than the opposite one. The former is bounded by a convex margin, the lat¬ ter by a concave one. Jbe orbit towards the former is large, the other small and imperfect. Conversely, it is to be observed, that in the latter the maxillary and intermax¬ illary bones are larger than in the former. The sides of the inferior jaw are less discordant; and though in the Sole and Plaice those of the eyeless side are more straight and elongated than those of the other, in the Turbot (Pleu- ronectes maximus) they are nearly symmetrical. CHAP. II.—COMPARATIVE MYOLOGY. Though this is the proper place to consider the pecu¬ liarities of the muscular system of animals, the limits as¬ signed to this sketch will not allow us to enter into de¬ tails. We shall merely, therefore, take a cursory view of those points in which the myology of the lower animals differs from that of the human subject. In general, in the lower animals, especially the Mam¬ malia, Birds, and Reptiles, the muscles correspond in situation to those of the human subject; and whatever modifications they undergo consist in changes of figure, and in some few instances in changes in attachment. The former kind of changes may be in all cases pretty accu¬ rately estimated by the osteological characters of the class, order, or genus; for when the position, shape, or direc¬ tion of a bone is altered, in the same proportion nearly are the attached muscles altered in their attributes. Though in the lower animals, however, the zootomist Deficiency traces muscles in general quite analogous to those of the in number, human subject, in several instances this analogy ceases to be observed. In general the muscles of the lower animals are less numerous than those of the human subject; and this deficiency in number, though not much observed in the Quadrumana, is very remarkable in all the inferior orders of the Mammalia, and still more in the Birds and Reptiles. In general, also, these variations are most conspicuous in the locomotive extremities. Thus the small pectoral muscle, which is present in the Quadru¬ mana, is wanting in the Carnivora and the whole of the Ungulated Animals and the Reptiles. The short supinator is present in the Canine and Feline genera, but the long is wanting; and both are absent in the Chirop- TERA, RoDENTIA, PACHYDERMATA, RuMINANTIA, and 92 ANATOMY. Compara- SotiDUNGULA, and in the whole class of Birds. Both t^ve pronators {teres and quadratus) are present in the Qua- drum ana and Carnivora, but wanting in the Chirop- tera, Ruminants, and Solidungula. The Rabbit, and perhaps the Rodentia generally, have the 'pronator teres; but as the radius is not very movable, its influence is trifling. Myologicai In the mole the rhomboideus is inserted into the cervi- peculiari- cal ligament, which is ossified; and it therefore elevates ties «t the t]ie ilea(j an(i neck on the scapula with singular force. This is effected still more remarkably by the occipital part of the rhomboideus, the fibres of which being parallel to the spine, pass below the proper rhomboideus to be attached to the transverse ligament and the middle of the cranium. The strong, thick, quadrangular collar-bone has two muscles, a supraclavius and a subclavius. The large pectoral is very thick, and nearly as large as in birds. The common extensor of the fingers or fore toes is the only muscle which is common to man and all the quadru¬ peds. Of the proper extensors the horse has two on the side of the common extensor, but acting as an extensor of the fore pastern; another between the common exten¬ sor and the extensor of the pastern, and which seems merely an appendage to the former. The proper extensor of the index is wanting in the Rodentia, Ruminants, and Solidungula ; and while the two latter orders are destitute of the long and short extensors of the thumb, and the feline, canine, ursine, and leporine genera have the former, they are destitute of the latter. Lastly, the lower animals are wholly destitute of the short muscles of the hand, which in man produce flection, abduction, adduc¬ tion, and opposition. In the Chiroptera only is there one extensor, and flexors of the fore toes. Among the muscles of the pelvic extremities the glu- t(BUS maximus, or large muscle of the buttock in man, di¬ minishes much in the Quadrumana; and in the other orders is reduced to a very small size. The buttock in the Mammalia generally consists chiefly of the glutceus medius and minimus ; and while the glutceus maximus is in the horse in a great part aponeurotic, the g. medius is so large as to produce those forcible and sudden extensions of the hind leg which constitute the kick. In the leg the sartorius of the horse, the animal in which the muscles have been most studied, is large, and is distinguished by the name of the long adductor, in op¬ position to the gracilis, which constitutes the short ad¬ ductor. The muscle representing the biceps of man is in all quadrupeds a uniceps, and the single head is attached to the ischium only. In the horse and dog it has been denominated the vastus longus. The gastrocnemius externus et internus (gemellus), which constitute the calf of the human subject, diminish consi¬ derably in the lower animals ; and the solceus, which is placed below them, also becomes small, and is particu¬ larly slender in the Ruminants and Solidungula. Afusdes The following muscles are wanting in the whole class wanting 0f Birds. The diaphragm, the recti abdominis, and the in birds, pyramidales ; the muscles of the dorsal part of the spine, the splenius, the brachialis externus, or third head of the triceps ; the supinators of the fore arm or wing, as already mentioned, all those corresponding to the short muscles of the hand and fingers ; the quadratus lumborum, the psoas parvus, the psoas magnus, iliacus internus, obturator externus, and the extensor longus pollicis pedis. Two muscles, which occupy the situation of the prona¬ tors, act as flexors, showing the connection between the actions of inflection and pronation, and the occasional substitution of the latter for the former. In this class, also, the glutceus maximus is of a pyra¬ midal shape, while the true pyriformis is wanting. The glutceus minimus, which is attached to the anterior edge Compara. of the iliac bones, is the iliacus. In place of the pectineus t|ve there is a slender muscle, which extends to the knee, on^' over which its tendon passes, and gliding behind the leg, its tendon is bifurcated, one slip going back to be inserted into the posterior part of the metatarsus, the other to be united to the perforated flexor of the first and last toe. This muscle, which is named the accessory femoral flexor, is the one by which birds are enabled to clasp a perch during sleep. In Birds the great pectoral is a remarkable muscle in Muscles point of size. It consists indeed of three muscles, themed in large pectoral, the middle, and the small, which occupy the sides of the vertical crest of the sternum, and consti¬ tute what is named the breast of the animal; and which are chiefly employed in the energetic motion of the wings in flying. These muscles are sometimes so large that they weigh more than all the other muscles of the animal together. In birds which fly much they are dark coloured and firm; in those which fly little, as the domestic poul¬ try, they are white coloured, and in general soft. The same distinction is observed in the muscles of the two ex¬ tremities. In birds much on the wing these muscles are dark coloured and firm, while those of the legs are com¬ paratively lighter and more tender; and, conversely, in birds little on the wing and mostly on the legs, as the domestic poultry and many of the Grallce, the waders, swimmers, &c. the muscles of the wings are light coloured and tender, while those of the legs are dark coloured, firm, and strong. The flexor muscles of the leg and toes of Birds merit Mecba. notice. They consist of muscles corresponding to thenism ,of long flexors, which are divided into three masses. ThePeiching’ first consists of five portions, three of which may be re¬ garded as constituting a single common perforated flexor. It rises by two bellies, one attached to the external con¬ dyle of the femur, forming a perforated tendon, which receives one of those of the muscle corresponding to the peronceus; the other to the posterior surface of the fe¬ mur, forming the tendons of the index and small toe. This muscle is further connected by intermediate fibres with the accessory femoral flexor,—a muscle placed on the internal surface of the thigh, and sending its tendon over the knee; and as the tendons are inserted into the unguinal phalanges, when the accessory femoral bends the thigh the flexors of the toes inflect them also, and retain them in the inflected position. By means of this arrangement birds are enabled to clasp a perch or other small body when roosting, without continued muscular effort, and thereby to sleep on the perch. This mode of explanation, which was originally given by Borelli, has been controverted by Vicq d’Azyr; but apparently not on good grounds. Among the class of Reptiles, while the muscles of the Ophidial family are confined to those of the vertebrae and rudimental ribs, in the Cheloniad these are oblite¬ rated, and the muscles of the neck, head, and tail, and those of the locomotive extremities alone, are left. In the other two classes of reptiles the muscles are in gene¬ ral analogous to those of the Mammalia. There are not many instances of muscles which, though Cutaneous unknown in man, are found in the lower animals. Of1111180*6, these the most remarkable are the cutaneous muscle {pan- niculus carnosus), and the suspensory of the eye. The former was absurdly maintained to exist in the human subject, especially by Nicolaus Massa ; but it is manifest that the assertion was derived from the dissection of the lower animals only. It was not long after demonstrated by Charles Etienne, that no fleshy pannicle or cutaneous muscle exists, such as is found in the lower animals; and ■■■■■ ANATOMY. 'ompara- live .natomy. 93 that the only cutaneous muscles in man are the htis- and so on to the 13th, each contained in a ligamentous ComparJ simus colli, the epicramus or scalp-muscle, and those P-rnnve. wWh fm-ma o*. r™ v ispen- ry mus- ? of the e proper certain imals. Ail, 41 caudal Mscles. simus colli, the epicranius or scalp-muscle, and those which are attached to the face, and which by their mo¬ tion give expression to the countenance. The cutaneous muscle even is not found in the Quadrumana, nor does it exist in the pig. In various other animals, however, it is found in different degrees of distinctness. It is very well marked in the hedgehog and porcupine;—by its means they have the power of erecting their spines, and rolling themselves up;—and in the armadillo and the ant- eater tribe. In the mole, also, we have seen it pretty well marked. It is an interesting fact, that Galen originally observed that the lower animals possess a seventh muscle of the eye, or one more than man. The suspensory or infundi¬ bular muscle (musculus choanoides), as it has been named, from its shape, especially in the Ruminants and Soli- dungula, has the apex fixed to the margin of the optic hole, and its base inserted a little behind the four straight five groove, which forms an investment. The muscles of both — sides acting together, elevate or incurvate the tail up- Anatom.v- wards. 1 The interspinalis and spinalis obliquus or lumbo-sacro- coccygeal are the continuations of the interspinales dor si et lumborum. The spinous processes, however, becoming indistinct, or being represented by two tubercles, the at¬ tachments vary. 2rf, The muscles which depress or inflect the tail down¬ wards take their origin within the pelvis, and are pro¬ longed to various extents along the inferior surface of the tail. Of these there are four pairs, the ileo-coccygeal of Vicq d'Azyr, the inferior sacro-coccygeal, the inter-coc¬ cygeal muscles, and the pubo-coccygeal of the same author. The insertions of these muscles vary in different genera, according to the number of vertebrae of which the tail consists. The pubo-coccygeal is wanting in the raccoon, but it is distinct in the dog and opossum. The effect of muscles. In the Zoophaga and Cetacea it consists of the ileo-coccygeal and it, is to depress the tail and apply four parts, sp that these orders appear to be provided it forcibly to the anus In the rhinoceros it consists of with 8 straight muscles, two portions. There is yet another part, the muscles of which can scarcely be said to exist in the human subject, but which attain a very great degree of developement in the lower animals. The coccyx of the human subject is expanded in the lower animals into a highly flexible prolongation denominated the tail (cauda), variable in length, but al¬ ways consisting of separate vertebrae, articulated and movable on each other. While the coccyx of the human subject possesses two muscles only, the ischio-coccygeus and sacro-coccygeus, which are so insignificant in size that they scarcely serve to move the part, the caudal verte¬ brae of the lower animals are moved by muscles greatly larger, more numerous, and more powerful. The tail is to animals a much more useful and power¬ ful organ than the coccyx to man. It is a member which peculiarly belongs to them; and though in ordinary cir- 3rf, There are only two muscles which carry the tail to the sides of the animal—the ischio-coccygceus externus, and the intertransversalis of Vicq d’Azyr; the former proceed¬ ing from the pelvic surface of the ischium below and be¬ hind the acetabulum, to the transverse processes of the cau¬ dal vertebraj, the second extending in a continued band between all the transverse processes. The tail, therefore, in the Mammalia, consists of a series of successively decreasing vertebrae, moved by eight pairs of muscles. In Fishes it is not easy to trace any analogy between the muscles and those of the other classes. Though the spine, head and fins, have appropriate muscular bundles, the natural or fascial distinctions are less evident than in the other three classes. It is important, however, to re¬ mark, that while the muscles which move the spinal co¬ lumn are placed in these classes, partly before, and chief¬ ly behind the vertebrae, those of Fishes are placed on cumstances pendulous, it is made to assume a variety of each side. Hence the lateral motion of the spine, which motions of which no other organ is susceptible, and to is inconsiderable in Mammiferous animals, Birds, and perform duties which would be otherwise impracticable. Reptiles, becomes very conspicuous in the finny tribes, With many, as the long-tailed monkeys, the sloths, the especially in the motion of swimming, while the antero- ant-eater, and the squirrel tribes, it is indispensable as an posterior inflection or extension is altogether insignificant. organ of prehension. The majority of animals, as the Ruminants, Solidungula, &c. use it as a whip or lash to drive away insects. The lion, tiger, and others of the feline tribe, lash their sides with it when enraged. The It is almost superfluous to remark, that, in the greater part of the finny tribes, the muscles are white or pale coloured. In a few only, for instance the salmon, trout, gwiniad (coregonus), herring {clupea harengus), carp (cy- Cetaceous swimmers employ it as a rudder and oar in the primes), and some others, are the muscular fibres of a pale waters. The beaver uses it as a trowel, to enable him to flesh red. The circumstances on which these differences construct his clay-built dwelling. An organ employed depend are not known; but it is supposed that in the so variously must consist of a muscular apparatus rather latter sorts the proportion of oleo-albuminous matter is C°miP j-ir more abundant tban in tbe former. The proportion of J he different motions of which the tail of the Mamma- albumen, however, in the muscles of fish, seems in general lia is susceptible may be referred to three heads,—one to be small. They abound in gelatine and isinglass; and by which it is extended or elevated, another by which it is inflected or depressed, and a third by which it is made to beat the sides. The combination or succession of these in some of the cartilaginous fishes especially, the greater part of the muscles seem to consist chiefly of gelatine in various degrees of consistence. This is particularly the ~ —vcmuua ucgicca ui cuiisisieiice. Ains is particularly tne motions gives rise to secondary ones more complex in case with the lamprey, the hag-fish (myxine glutinosa), character. It may be twisted on its axis, or turned in a and even with the sturgeon. The sterlet especially (aci- sPira direction. These motions are effected by three a small species of sturgeon found in the casses o muscles. rivers of Russia, both European and Asiatic, abounds in s > ie muscles which raise the tail are situate above ; gelatine ; and the presence of this principle enables the iey aie musculi sacro-coccygeci superiores. Commenc- inhabitants to use it in the preparation of a species of ing at t ic base of the articular processes of the 3 or 4 soup, the sterlet, which is esteemed a great delicacy. In as um iar vei tebrae, or those of the sacrum and the cau- some of the genus Pleuronectes this principle is also very dal vertebrae, by fleshy slips, they are connected to ten- abundant. Thus the Plaice {Pleuronectes Platessa), sole on*’ vv uc 1 aie inserted into the base of the first of the {P. Solea), and especially the turbot (IP. Maximus), con- cauc a vtitebiae, which are void of articular processes, tain a considerable proportion of gelatine. On the pro- 1 lie second tendon goes to the next following vertebra, portion of this principle depends the quality of fish used 94 A N A T Compara- as an article of food in nourishing without exciting. All tive fishes which abound in gelatine uncombined with oleo-al- Anatomy; luminous matter may be safely used as articles of food; ■vvhiie those in which the latter ingredients predominate are invariably eaten with the risk of disordering the sto¬ mach and producing indigestion. CHAP. III.—COMPARATIVE iESTHIOLOGY, OR THE COM¬ PARATIVE ANATOMY OF THE ORGANS OF SENSATION. SECT. I.—THE ORGAN OF SMELL. The organ of smell consists of the nasal cavities, those of the ethmoidal and turbinated bones, and the frontal, sphenoidal, and superior maxillary sinuses, all of which communicate with the nasal. The whole of these parts are invested by fine periosteum, lined by mucous mem¬ brane. The ethmoid bone is the essential organ of smell; and the others appear simply to multiply the extent of the membrane. The ethmoid bone consists of a perforated plate, with a middle vertical one attached at right angles to it, and lateral portions composed of thin bony plates convoluted with various degrees of complexity and minuteness in Ethmoid different orders and genera of animals. These convoluted cells. plates form what are denominated the ethmoidal cells. They may be represented as numerous tortuous canals, proceeding from the perforated plate forwards and out¬ wards, approximating mutually, and forming numerous communicating cavities. Such nearly is the structure of these plates in the Edentata, Ruminantia, Solidun- gula, Pachydermata, and Carnivora, the last of which have more complicated cells than the first. In the dog they are numerous and extensive. In the Rodentia, for instance the porcupine, they are few—not above 3 or 4 on each side. In Birds the internal side of each nostril is occupied by three orders of plates; the inferior turbinated or spongy bone; the middle, consisting of one plate convo¬ luted on itself two turns and a half; and the upper, shaped like a bell, adhering to the frontal and lacrymal bones. These form three tortuous passages, varying in size and tortuosity in different genera. Though generally carti¬ laginous, these turbinated bones are membranous in the cassowary and albatross, and bony in the calao and toucan. In the nostrils of Reptiles there are convoluted pro¬ minent plates, which, however, are merely membranous productions, unsupported by any bone. In the Fishes, in like manner, there are membranous folds, the disposition of which is tortuous. They are, however, more regularly arranged than in the other classes. In the cartilaginous fishes they consist of semi¬ lunar folds placed in parallel tracts on each side of a broad plate, which divides the one side of the nasal cavity from the other. In the sturgeon, however, they are ar¬ ranged in diverging plates, which are subdivided into more minute ones, like the branches of a tree. In the osseous fishes generally they consist of radiating plates disposed round a prominent central tubercle. In these three classes the olfactory nerve is distributed to the membrane much in the same manner. This nerve, however, does not proceed farther than the superior tur¬ binated bones; and the middle and inferior appear to be supplied with filaments of the fifth pair, the naso-oph- thalmic branch of which is distributed to the nose in all the vertebrated animals. In the Mammalia, further, the spheno-palatine ganglion sends several filaments to the posterior part of the narine membrane. By most zootomical authors the trunk of the elephant has been described as an organ of smell peculiar to that O M Y. animal. We are satisfied, however, from observing the mo- Conipara. tions of this body in the living animal, that it is an organ, hve not of smell, but of prehension. Cuvier, after adopting the ordinary view, has relinquished it, and, on the ground '(~>J of personal inspection, admits that the sense of smell in the elephant is confined, as in other animals, to that por¬ tion of the nasal cavities which is contained within the bones of the head. The trunk of the elephant, therefore, will with greater propriety be noticed under a subsequent head. The nasal cavities of the Cetaceous animals are not so much organs of smell as channels of respiration, and must also be noticed afterwards. It is sufficient here to remark, that in these animals the part of the cranium cor¬ responding to the ethmoid bone is penetrated by no aper¬ ture, or, in other words, is not an ethmoid bone. It has therefore been asserted that the Cetacea have no olfac¬ tory nerve, and no sense of smell. This, however, is by no means established. Blainville and Jacobsen have ob¬ served in the dolphin nerves which they regard as olfacient; and Treviranus delineates nerves of the same character. By Otto and Rudolphi, on the contrary, who have had frequent opportunities of dissecting the dolphin and whale, the existence of these nerves is denied. Though almost all the invertebrated animals give proofs Smell in of the existence of the sense of smell, in none of them do mverte. we find any organ in wdiich this sensation appears with t)rate(l ani- certainty to be exercised. That these animals possessma3, the faculty of smell, is inferred from the fact, that insects recognise their food at a distance; that male butterflies scent the female even when inclosed in cages; and that the ordinary flesh-fly deposits her eggs on tainted meat, and occasionally on fetid plants, in the belief that they are the proper nidus, though in the latter case the larvae perish for want of the necessary sustenance. Since odorous particles are evidently applied to the ol¬ factory membrane of all aeropnoic animals by the me¬ dium of the atmosphere, and since the organ of smell is therefore situate in connection with the wind-pipe, it was conjectured by Baster, that, in insects at least, the organ of smell is situate at the entrance of the tracheae or air- tubes. This conjecture derives some probability from the fact, that the inner tracheal membrane in these animals is soft and moist, and that those in which it is expanded into convoluted lacunae and tortuous vesicles, for instance beetles, flies, and bees, are remarkable for the nicety of their sense of smell. The antennae, in which this sense has been placed by some anatomists, appear to be rather organs of touch than of smell. In the Mollusca the whole cutaneous covering seems to combine the character of an organ of touch or tact, and of smell. Like an extensive pituitary membrane, it is soft, villous, moist, and liberally supplied with nerves. The Articulata and Zoophytes seem much in the same state. But on all these points information is rather con¬ jectural than positive. SECT. II. THE EYES ; THE ORGANS OF VISION. All red-blooded animals, without exception, are pro¬ vided with two movable eyes, consisting of the same es¬ sential parts as those of man, forming globular organs, and placed in the cranio-facial cavities named orbits. In none are there more or fewer; and the exceptions to the general rule, either in relation to the presence of these organs, or number, are only apparent. Among the Mammalia, Blind indeed, there are two instances of blindness,—in the zemm though not or blind rat (Jttus typhlus, Lin.; Spalax typhlus, Pall.), ande.vfle^ the golden mole (Talpa Asiatica, Lin.; Chrysochloris,anima Lacep. and Cuvier). But in neither of these animals are ANATOMY. ompara- tive n atomy. (jure of e eye- U. cis and iiuneter. ^ ueous •l incur. Axis. Man and ape 137.. Dog 24.. Horse 24.. Ox 20.. .136 . 25 . 25 . 21 the eyes absolutely wanting; they are merely very mi¬ nute, and covered by a thin fold of hairy skin, in which there is said to be no aperture. Much in the same man¬ ner the murcena coecilia, and the hag-fish (jnyxine, Lin., gastrobranclms ccecus), though provided with eyes, are de¬ prived of the use of these organs by the opacity of the con¬ junctiva. In the Anableps (Cobitis Anableps, Lin.), the cornea and iris are biparted by transverse bands, so as to give the animal the appearance of having two pupils in each eye, though the crystalline lens, vitreous humour, and retina, are single. This animal affords the only ex¬ ample of this structure among the vertebrated animals; but a similar arrangement is observed in the Cephalopo- dous Mollusca and cuttle-fish family. The general shape of the eye depends on the medium in which the animal lives. It is nearly spherical, or ap¬ proaching the spherical shape, in man and the quadrupeds moving along the surface of the earth; that is, in the lowest and most dense region of the atmosphere. The cornea merely forms a slight convexity, in consequence of being the segment of a smaller sphere than the rest of the eyeball; yet in the porcupine, opossum, &c., this difference is inconsiderable. To show the degree of this convexity, it is merely requisite to compare the axis or antero-posterior diameter with the transverse diameter of the ball, as exhibited in the following table:— Tr. Diam. Axis. Tr. Diam. Whale 6 11 Porpoise 2 3 Owl 13 12 Vulture 13 16 According to the measurements of the younger Soem¬ mering, the axis of the human eye, taken in a beautiful Tyrolese girl of 20, is to the transverse diameter as 100 to 95; that of the eye of the magot (simia inuus) as 85 to 84 ; and that of the bat (vespertilio auritus) as 12 to 11. In the raccoon (vrsus lotor) and lynx (j'dis lynx) alone the axis is exactly equal to the diameter. In all the other ver¬ tebrated animals, it is, as in the measurements of Cuvier, less than the transverse diameter at the rate of from 9 to 33 or 45 per cent. In the horse it is as 186 to 212, in the seal as 130 to 142, in the Indian elephant as 135 to 180, and in the black whale (balccna mysticetus) as 20 to 29. In the owl it is as 17 to 18, in the golden falcon as 141 to 16, in the ostrich as 18 to 191, and in the swan as 7 to 10. In the Reptiles and Fishes it is always less at the rate of from 3 to nearly 10 per cent. In the cuttle-fish, which may be taken as a general example of the inverte- brated classes, it is much greater, the axis being to the diameter as 80 to 57. (D. W. Soemmering de Oculorum Hominis Animaliumque Sectione Horizontali Commentatio. Goetting. 1818, fob) In Jishes and the Cetacea which inhabit the sea, the anterior part of the eyeball is much more flattened, and in many fishes it resembles a hemisphere with the plane surface before and the convex behind. In the ray genus the superior part is also flat, so as to give the eye the ap¬ pearance of the quadrant of a sphere, cut through two large circles perpendicular to each other. In some fishes, especially the burbot ( Gadus Lota), the cornea is convex. In Birds which occupy the elevated regions of the at¬ mosphere, the deviation from the spherical shape is in the direction opposite to that of fishes. On the anterior part, winch is sometimes flat, sometimes shaped like a truncat¬ ed cone, is chased a short cylinder, closed by a very con¬ vex, and occasionally hemispherical cornea, always be- onging to a much smaller sphere than the posterior con¬ vexity. ihese differences in shape depend on the proportion be¬ tween the density of the medium in which the animals live 95 and that of the aqueous humour. In the higher regions of Compara- the atmosphere, in which the air is very much rarefied, the tive refracting power of the aqueous humour is much more con- Anatomy, sideiable than at the surface, occupied by quadrupeds; and hence it is more abundant in the former than in the latter class. Its refracting power, however, would be almost extinguished in a watery medium, from which it could differ but little in density ; and hence it is either trifling or absolutely wanting in the inhabitants of the deep. In the cuttle-fish family it is entirely wanting. The crystalline lens in Fishes, which is nearly spheri¬ cal, projects through the pupil, and leaves little room for the aqueous humour. The lens is also very convex in the Cetacea, the Amphibious Mammalia, the diving birds, as the cormorant, and the marine and aquatic Reptiles. Affecting the oblate spheroidal shape in the Mamma¬ lia, it becomes extremely so in man, and still more in Birds. Its consistence is greatest in animals in which it is most convex , and hence it is matter of common obser¬ vation, that the crystalline of fishes is particularly firm. It also contains rather more albumen than the lens of the Mammalia. The crystalline lens occupies least propor¬ tional space of the eyeball in man, and most in fishes. The comparative spaces occupied by each of the hu¬ mours may be understood from the following table, in which the axis of the eye, or the space occupied by the whole three humours, is represented by unity. Man Log Ox Sheep Horse Owl Herring Aqueous Humour. Crystalline Humour. Vitreous Humour. •If 9 ■43- •25 8 •21 1 8 •37 J 2 T 7 1 8 "4 3 8 •57 On the proportion of the total volume occupied by each of the three transparent parts there are few accurate facts. It may be remarked, however, that the human eye among the Mammalia is that in which the vitreous humour is proportionally most abundant. It is estimated to be twenty times more copious than the aqueous. In the ox it is only ten times, and in the sheep nine times the quantity of the aqueous. In the Mammalia generally, the sclerotic is compa-Sclerotic, ratively elastic, soft, and yielding; but in all animals in which the eye deviates from the spherical shape, as the Cetacea, Fishes, and Birds, this membrane is strength¬ ened by greater solidity and thickness of tissue, or sup¬ ported by accessory parts of a hard unyielding structure. In the eye of the whale these two parts, the hard and soft, are naturally distinguished in a very striking manner. 1 he lateral parts of the sclerotic are nearly an inch thick, and very hard. The posterior part is about one and a half inch thick, and softer, because the spaces between the firm fibres are filled with oily substance. The posterior part presents for the optic nerve a canal one and a half inch long, the walls of which are formed chiefly by fibres in direct continuity with the dura mater,—the only fact, it may be observed, which favours the statement of the ancient anatomists, that the sclerotic is derived from the dura mater. The sclerotic of the porpoise, though only two or three lines thick, has the same structure as that of the whale. In the seal it is thick before and thicker behind, but the middle zone is thin and flexible. The sclerotic in Birds is thin, flexible, and elastic be-Osseous hind, with a bluish glistening aspect, and without distinct zone of fibres. The optic nerve enters, not by a hole, but an ob-birds, lique canal. The anterior part consists of two plates, be¬ tween which is enchased a zone of thin, hard, oblong, osse- 96 ANATOMY. and rep. tiles. Cornea. Compara- ous scales, varying in number from 11 or 12 to 14 or 15, tive imbricated over each other so as to give the anterior part Anatomy. 0p t]ie eyebaU a great degree of hardness, and a figure unsusceptible of change. Though these plates are nearly flat in most birds, and form an annular zone slightly con¬ vex, they are broad, arched, and concave internally in the owl genus, and form a bell-shaped tube, with the posterior aperture oval and the anterior round. This may be de¬ nominated the osseous ring {annulus osseus, zona ossea). In the ostrich it is narrow and flat. Among the Reptiles, the Cheloniads possess an osse¬ ous zone, consisting of plates inclosed in the membrane without being continuous wkh its substance. They are also found at the lateral part of the sclerotic in the cha¬ meleon and some of the Saurial Reptiles, as the Croco- dilus Sclerops and Lucius, the monitor, and the iguana (D. W. Soemmering). It is also an important character in the structure of the eye of the Ichthyosaurus, which indicates the connection of that animal with the Saurial tribe, that its sclerotic was provided writh an osseous zone, con¬ sisting, as in these, of 13 separate pieces. In Fishes the sclerotic is cartilaginous, homogeneous, semi-translucent, elastic, and, though thin, firm enough not to collapse. In the ray it is expanded into a tubercle, by which the eye is attached to a peduncle or stalk. The sclerotic of the sturgeon is so thick that it resembles a cartilaginous sphere, with the external part hollowed for the humours and membranes. In the Cephalopodous Mollusca it forms behind a truncated cone, with the apex at the bottom of the orbit containing the gangliform swelling of the optic nerve, and several glandular parts, with the eye before. The cornea has often been represented to be merely a continuation of the sclerotic; and though this is easily disproved by accurate dissection of the human eye and that of our ordinary domestic animals, its inaccuracy is much more manifestly demonstrated in the animal world at large. In the whale and rhinoceros the margins of the two membranes penetrate reciprocally. In man and the ox the corneal margin is enchased within the sharp im¬ bricated edge of the sclerotic. In the tope-fish {squalus milandra, Lin.; galeus, Cuv.) the cornea is observed dis¬ tinctly passing within the sclerotic in the manner of im¬ brication. The cuttle-fish is destitute of cornea ; and as there is no aqueous humour, the crystalline lens is cover¬ ed by a fine thin membrane, extended beneath the con¬ junctiva. In all animals provided with eyelids, the mucous mem¬ brane, after being folded behind the eyelids, is reflected forwards over the sclerotic and cornea, in the form of g thin, transparent membrane. In those void of eyelids, as most fishes are, the skin, passing into mucous membrane, is continued directly over the cornea, without forming any angular fold, and adheres strongly. This is very dis¬ tinct in the eel, which may be flayed without leaving any trace at the site of the eyes, except a round, translucent spot. The same peculiarity is remarked in Serpents and in the cuttle-fish family. In the zemni, golden mole, blind eel, and hag-fish, it has been already stated that the cornea is covered by opaque mucous membrane. The choroid coat exists in all animals yet examined. It is always very vascular. The inner layer, which has been Ruyschian distinguished by the name of tunica Ruyschiana, can scarce- membrane. jy be gaid to exist in man, small quadrupeds, and birds. In the large quadrupeds, however, especially the Cetace¬ ous animals, it appears in the form of a distinct simple membrane like epidermis. The lateral and anterior parts of the membrane are always invested by a semifluid, viscid substance, of different shades of black or brown black {jpig- mentum nigrum); chocolate brown in the hare, rabbit, and Corneal conjunc¬ tion. Choroid coat and pig; deep red brown in some birds; and purple red in Compara. the calmar. The absence of this dark-coloured pigment, tive which is not unfrequent, is observed in albinos, both hu- man and animal, for instance white rabbits and white mice. The transparency of the Ruyschian membrane then shows the choroid of its natural red colour ; and the pupil is red and contracted, and the eye intolerant of light. In the Zoophaga, Ruminantia, Pachydermata, So- The ta. lidungula, and Cetacea, the concave or inner surface Petl™. or of the Ruyschian membrane is diversified with colours of™^06 metallic lustre, more or less brilliant and something irides- cent. In the ox it is of bright metallic green, changing to sky-blue; in the horse, buck, buffalo, and stag, it is a silvery blue passing to violet; in the sheep of a pale golden green, sometimes bluish ; in the lion, cat, bear, and dol¬ phin, of a pale gold yellow; and in the dog, wolf, and badger, of a pure white, surrounded by blue. This coloured part of the inner choroid surface, which occupies chiefly the side opposite to that on which the optic nerve enters, is named the tapetum. The use of it is by no means obvious. The explanation of Monro in reference to the tapetum of the ox, that it represents more distinct¬ ly to that animal the colour of his natural food, is not only frivolous, but inapplicable to the other genera. The tapetum is wanting in all Birds and Fishes, ex¬ cepting the ray, in which there is at the bottom of the eye a beautiful silvery-coloured space, produced by the trans¬ parency of the Ruyschian tunic, through which the tint of the choroid is seen. In Fishes generally the choroid consists of two dis-Thecho. tinct separable membranes; the external, the proper cho-™^121^ roid, white, silvery, or golden, very thin and not vascular; 5 ^ and the inner or Ruyschian, black, and consisting of a net¬ work of vessels. Between these two membranes is a body of a bright red colour, consisting of numerous tortuous vessels, convoluted and inclosed in pulpy filamentous tissue. Its general shape is that of a thin cylinder, en¬ compassing the optic nerve like a ring, which, however, is incomplete at one side. This is the choroid gland,—a body about which there has been some difference of opi¬ nion, but which appears to be glandular rather than any thing else. Its vascular structure is well seen in the globe-fish, perca labrax, and cod, in which they are very large, and form numerous anastomotic communications. They are generally covered by a white, opaque, viscid fluid. The choroid gland is wanting in the Cartilaginous Fishes, the eye of which approaches more nearly to that of the Mammalia in this as in other circumstances. The choroid of the ray and shark genera is a threefold tissue of vessels, thick and consistent; the tunica Ruyschiana is very thin and semi-transparent; and between these is a layer of silvery matter with metallic lustre. In the cuttle-fish genus, though between the sclerotic and choroid there are several glandular bodies, there are none between the choroid and Ruyschian tunic. The choroid is thick, soft, and vascular; the Ruyschian thin, firm, and dry ; and though there is no tapetum, the whole interior surface of the eye is covered by deep purple, semi¬ fluid, viscid varnish. Ciliary processes are found in all the Mammalia, Birds, Ciliary several Reptiles, and even in the cuttle-fish among Mollusca ; but they are wanting in almost all fishes. an The indented border of these processes is more dis¬ tinct, and is converted into a genuine fringe in the large animals, as the ox, horse, rhinoceros, and whale, in which the angle applied to the capsule is more acuminated than in other animals. In the Carnivora, particularly the lion, the base of the plates is shorter in proportion to the other sides than in the previously mentioned animals, so that the opposite angle is more prominent; nor is the ANATOMY. Compara¬ tive Anatomy, The iris uid uvea. border indented. In all the species every third or fourth plate is shorter than the others, but without determinate order. The ciliary plates of Birds are mere serrated stria, without sufficient prominence to make them undulate in fluid. In the owl they are fine, closely set, and nume¬ rous ; in the ostrich they are larger and more numerous; and in all, their extremities adhere firmly to the capsule of the lens. In the tortoise the ciliary processes are so short that they are recognised only by the impression left on the vi¬ treous humour; in the crocodile, however, they are dis¬ tinct, and terminate each by an angle nearly right. They are indistinct in the toad, and imperceptible in the ordi¬ nary lizards and serpents. The ciliary body and processes are large and distinct in the tope-fish; but if they are seen in any other of the car¬ tilaginous fishes, they are wholly wanting in the osseous, in which the Ruyschian tunic is directly continuous with the uvea. The utility of these processes in retaining the lens in its position is nowhere so distinctly seen as in the eye of the cuttle-fish family, and especially the many-feet of the ancients (polypus octopoda'). In these the ciliary pro¬ cesses form a large diaphragm or zone, in the aperture of which the crystalline lens is truly chased. They pene¬ trate a deep annular furrow which sorrounds the lens, dividing it in two unequal hemispheres, and cannot be de¬ tached without laceration. The iris, of the same intimate structure as in man, is of a deep tawny or brown in the Mammalia, and marked with fewer coloured stria than the human iris. In Birds it is of a uniform lustreless colour, varying according to the species, bright yellow, red, or clear blue. In the microscope it appears like a net-work formed by the in¬ tersection of numerous very minute fibres. The uvea is so fine that when the viscid varnish is removed it be¬ comes transparent, and the iris appears of the same colour on both sides. In Fishes, conversely, the iris is so thin and transparent that the uvea is seen through it, of a golden or silvery brilliance, showing its direct connection with the choroid. Intermediate in metallic splendour is the iris of the Reptiles. The vessels, however, are greatly more conspicuous, especially in the crocodile. The central aperture or pupil, though round in man, the Quadrumana, many of the Carnivora, and Birds, is not of that shape when contracted in all animals. In the feline family it consists of two elliptical segments, which form angles above and below, and which approach mutu¬ ally so as to form a slit nearly vertical. In the Ruminants it is oblong transversely, and forms at its greatest contrac¬ tion an oblong or transverse slit. In the horse, in which it is also transverse, its upper margin is distinguished by a five-pointed festoon. In the whale it is oblong transverse¬ ly, and in the dolphin it is heart-shaped. The pupil of the crocodile resembles that of the cat; in the frog and gecko it is rhomboidal; and round in the tortoise, chameleon, and common lizards. In the ray among Fishes the upper margin forms several radiating slips like the branches of i G P^m'tree> gold-coloured without, dark within. In t e dilated state these slips are folded backwards between t le upper margin of the pupil and the vitreous humour; but when the eye is pressed they are erected, and close the pupil like a blind. The motion of the pupil is voluntary in the parroquet, an^p.ls lnd1stinct in most of the Fishes. ie pupillary membrane is well known to exist in the foetuses of all the Mammalia ; but it is not determined whether it is found in the chick of birds. On the subject of the retina in the lower animals the VOL. m. 97 ost important point is the structure of the melanoplectic Compara- or pectimfoim membrane (pecten, marsupium nigrum) of tive • Dfi' t\t lhlS C aSS tl?e °Ptic nerve forms not a round disk Anatomy, as in the Mammalia, but a narrow white line, the margins and extremity of which are in continuity with the retina The™hl- Along this line is suspended a plicated or convoluted membrane “T ^ fi"e ,and vascular ^ structure, like the or™!"-’ choroid, from which, however, it is quite distinct, and en-P™m ni- tering a depression of the vitreous humour almost like a^rumi and wedge. Its vessels, which proceed from a proper branchits of the ophthalmic artery, are distributed in a minute arbo rescent form, among the folds of which the marsupium con¬ sists; and from these vessels the black viscid pigment with which its folds are covered appears to be secreted. The plica or membranous folds vary in number. In the" casso¬ wary they are only 4; in the brown owl (S. aluco) 5 ; in the common owl, ostrich, Guiana macaw, and merganser, they are 7 ; in the flamingo 9 ; in the falcon and swan 11; in the vulture and goose 12 ; in the duck, large heron, woodcock, and coot, 13; in the stork and partridge 15; in the crane 17; in the pheasant 20; in the turkey 22 ; in the jackdaw 25 ; and in the thrush 28. According to the observations of the elder Soemmering, to whom we are indebted for these numbers, the number of folds, though variable in different species, is the same in the same. In most birds the folds are arranged in a pectiniform order. On the use of this organ different opinions have been entertained by Petit, Haller, and Home ; but all of them are conjectural. In the Reptiles and many Fishes, between the optic nerve and the retina is a small tubercle, from the margins of which the latter membrane appears to rise ; and radiating fibres are perceived more distinctly than in most quadru^ peds. In many other Fishes the connection of the reti¬ na with the optic nerves resembles that of Birds. Thus, in the salmon, trout, herring, mackarel, cod, dory, and moon-fish, the optic nerve, after passing through the Ruyschian tunic, appears to be parted into two long white processes, which, following the outline of this membrane parallel but not contiguous to each other, are connected with the retina by their opposite margins. In all animals provided with ciliary processes the retina terminates at and is connected with the gray pulpy zone denominated ciliary ligament. In those without ciliary processes, as the Fishes, it terminates suddenly at the attached or large margin of the uvea. In several of the reptiles the retina presents the yellow spot of Soemmering. The principal peculiarities of the humours have been already mentioned. Of the appendages the most important are the lacrymal gland and nictitating membrane. In the Ruminants the lacrymal gland consists of two or Lacrymal three bodies, each composed of granules, each provided gland, with a separate short excretory duct. In the hare and rabbit, in which the gland is large, there appears to be only one excretory duct, which perforates the upper eye¬ lid near its posterior angle. A gland peculiar to certain species, and wanting in man, that of Harder, is situate at the external or nasal angle, and presents an aperture under the third or nicti¬ tating eyelid, from which issues a thick viscid fluid. It is found in the Ruminants, the Rodentia, the Pachy- dermata, and in the sloth genus. The caruncle exists in the Ruminants as in man, and appears to consist of numerous aggregated follicles. It is wanting in the Rodentia. In the Cetacea, as in most animals which live under water, there is neither gland nor lacrymal passages ; and they are represented apparently by lacuna below the up¬ per eyelid, which discharge a thick mucilaginous fluid. Birds, though destitute of caruncle, have both lacry- N 98 ANATOMY. Compara- mal gland and that of Harder, the latter large, oblong, tive and flesh-coloured, placed betwixt the levator and adductor, Anatomy. ant\ discharging by a single canal, opening at the inner surface of the third eyelid, a thick yellow fluid. The la- SECT. III.—THE EAR. Compara- tive In warm-blooded animals generally, that is, in the Mam- MALIA and Birds, the labyrinth or essential part of the Mucipa¬ rous folli¬ cles. crymal, which is small, round, and very red, is provided organ consists of three sem'^cuaica > g in general with two or three canals, which, though small, enlargement to each (aw^Za), a ca ty t are distinct. In most of the Grall* and Palmiped canals named vestibule Birds there is, in place of the lacrymal gland, a hard granular body, occupying the upper part of the orbit, and following in "situation the curvature of the eye. It has, nevertheless, no visible excretory duct. In the turtle there is a reddish granular lobulated body, of considerable size, extending beneath the temporal vault. In the tortoise, frog, and toad, there are two small blackish glands without apparent excretory ducts. Neither in Serpents nor Fishes has any glandular apparatus in the eye been recognised. The third Though in man and the monkey tribe the eyelids eyelid or consist of two semilunar cutaneo-muscular folds, with a nictitating minute mucous duplicature at the nasal angle, the latter membrane. acqUires such a developement in the lower animals as to constitute a genuine third eyelid, often distinguished by the name of nictitating membrane. I his duplicature is semi- canais nauicu ^ , • * j. ing canal, divided into two compartments by a longitudi¬ nal septum. This may be named the bilocular cone (corcw bilocularis). These parts consist of membranous substance inclosed in the bony walls of the pyramidal or auditory bone. In all the Mammalia the bilocular conical canal is convo¬ luted in a spiral form, and hence is denominated, as in man, the cochlea—a name, however, which is applicable to it in this class only. . , The organ of hearing in the Mammalia consists of the same parts nearly as in man. In some, indeed, f°r in- dtnnce the euinea-pig (cabiai), and porcupine, the cochlea Cochlea makes ftree turns and a half; and, conversely, in the Ce- and c* TACEA only one and a half. In most of the Zoophaga, and in the hog, elephant, and horse, the cochlea is much laro-er in proportion than the semicircular canals ; but in the hare it is small, and in the mole very small. In the of this the Cetacea present no trace. In the Birds, on the contrary, in which the eye is covered by the eleva¬ tion of the lower eyelid, which is also the largest, the third eyelid is large, and covers the eye like a blind drawn before it; yet it is in some degree translucent, for it is evident that birds see objects through the membrane. In semicircular canals are so small, that their existence was long denied by Camper, till they were demonstrated by Cuvier in a foetal whale. In general the labyrinth of the Mammalia is greatly smaller in proportion to the head than in Birds. . . .. This part, which is membranous, is inclosed in the solid * n .1 . 1 : A 4-V»r»f ^T^rf«he«eTrdp™id.rdorlyA«« sion of the upper as well as the elevation of the lower ^ existence appears to be .dent.fied w.th the a . eyelid. Though the Serpentine reptiles are void of eyelids en¬ tirely, in the crocodile, tortoise, and Batrachoid, theie are three, as in birds, the third being vertical in the two former orders, and horizontal in the latter. In the Saurial and Cheloniad, also, the third, which is translucent, moves from before backwards by means of a single muscle, and may cover the whole eye. In the lizard genus the eyelids consist of a circular veil drawn before the orbit, and per¬ forated by a horizontal fissure, which is shut by a sphinc¬ ter, and opened by a levator and depressor. The gecko has no movable eyelid. Compound 1° insects, the eye consists of innumerable hexagonal eyes of the surfaces, slightly convex, and mutually sepaiated by mi- Articu- nute furrows, containing fine hairs variable, in length. lata. Each of these hexagonal surfaces, which constitute a hard, elastic, very transparent membrane, may be regarded as a cornea or crystalline lens, convex externally, concave within, and thicker in the centre than on the margins. Immediately behind is an opaque, viscid coating, varying in colour in the different species, analogous to the choroid pigment of the vertebrated animals, and completely ob¬ structing the transmission of light. Beneath this varnish are short, whitish filaments, corresponding in number to the corneal surfaces, and mutually joined like mosaic or tessellated pavement, separated only by the dark-coloured pigment, and which appear to correspond to the retina of the Vertebrata. Behind these again is a delicate, dark- coloured membrane, which appears to correspond to the choroid; and exterior to this is a membrane continuous with the optic nerve, and which seems to be a general re¬ tina, forming, by subdivision of its parts on the anteiior part of the choroid, the divided or multiplied retina. This is the structure of what are named compound eyes. That of the simple eyes of insects is too minute to be accurate¬ ly demonstrated; but analogy gives probability to the in¬ ference that they are not dissimilar. searches, however, on the labyrinth in the foetus of the Mammalia, and especially in those of whales, demonstrate the fact that it is in a completely membranous form, dis¬ tinct from the bony inclosure; that in shape and consti¬ tuent parts it exists previous to the bony inclosure ; and that the latter is afterwards moulded round the different parts as they acquire their full developement. It is also to be observed, that in the mole the semicircular canals are seen within the cranium without preparation, and the cochlea is merely inclosed in fine cellular tissue. In the bat family, also, both parts are seen without bony inclo- sure. . . The tympanum forms a cylindrical or spheroidal cavity in Tympa. most of the Mammalia. In most of the Digitata thenum* mastoid process consists of a slight prominence of the tym¬ panum only as it is identified with the latter; but in the cabiai, guinea-pig, hog, the Ruminants, and So.lidungula, it is represented by a long process of the occipital bone. In most of the Zoophaga and Rodentia the parietes of this protuberance, which are thin and hard, form by their se¬ paration a large cavity. In the hog only it is occupied by a firm cancellated structure. All the Mammalia, except the ornithorhyncus, have the Tympanal tympanal bones as in man; the hammer (malleus), anvil bones. (incus), orbicular bone and stirrup (stapes). The lenti¬ cular bone, which is rarely found in the adult, is probably only an epiphysis of the anvil. They are articulated with each other so as to admit of motion, and are moved by the same muscles as in the human subject—the internus mallei, externus mallei, laxator tympani, and stapedius. In the ornithorhyncus, however, there are only two tympanal bones. In all the Mammalia, except the Cetaceous, the ear Externa is provided with a bony external canal (meatus)-, and3?611111’6, most of the Mammalia, except the Cetaceous, have a cartilaginous funnel-shaped opening (concha) attached to the outer margin of the bony meatus, and which serves to Compara¬ tive Anatomy. ANATOMY. collect the sonorous vibrations, and direct them to the double canal, one senaratpA ^J meatus. The other exceptions are among the Insecti- hole from the tympanal ^ o me"lbrane ot the. round Co»?Para- vora, the mole, and some of the shrew oenus • amonn- with a cavity> the other communicating tive ' the Rodentia, the zemni or blind rat, and some of the rat? stones, not harder than sterch^flthl66 Ve7 ^ friabl-e mole genus ; among the Edentata, the pangolin or scaly circular canals of considerable sTze^each tW° ^ f™1' ant-eater; and among the Amphibia, the morse and se- circumference. In the froir and toad’wt? 7r™InS a larSe vera species of seal; and the ornithorhyncus paradoxus. form almost a complete cfrcle ^ n fnmin, 66 SLith0ph0' . rhe tympanum of the Cetacea is peculiar. It con- ceous friable stone • but the bilornlar • an amyla-r°as sacs sists of a bony plate, convoluted on itself like a buccinum, observed. In the salamander also hi wl7 h 1° °nger kceouT* unless that the thick side instead of containing a spiral canals form together cavity, is entirely solid The opposite side is thin, Lh which is belowcontains a sing^amylacl^ sfon’e The an irregular margin The anterior extremity of the tym- same arrangement is observed in the^arTat-inous FisW. panum is open, and there commences the Eustachian unless that the sac contains two amylaceoSones near tube, which ascends along the pterygoid process, and, pe- ly oval in shape, suspended in a geliLous semifluid nuta Of thenti Tr T f6’ tefrTateSt,at thf upper part In the 0sseous Fish“ !t is “ little different The ,hre- of the nose. 1 his direction of the tube and position ot semicircular canals terminate in a membranous sac which its orifice is so niuc'h more necessary, because, since these is divided by septa into compartments which contain one, stones appear. animals have no external bony meatus, and the ear-hole scarcely admits a pin, the vibrations of the air reach their organ of hearing entirely by the Eustachian tube, and because the Eustachian tube also in these animals conveys odorous impressions to the part in which the sense of smell appears to reside. The aperture by which it communicates with the nose is provided with a mem- two, or three small stones suspended in gelatinous fluid! These minute stones, however, instead of being soft, fri¬ able, and amylaceous, as in Reptiles and cartilaginous Fishes, are as hard as rock, and white as porcelain. These parts are situate on the sides of the cranial cavity, and are fixed to it by cellular tissue, vessels, and osseous or cartilaginous processes. This sac, in the fluid of which Bilocular one no onger spi. al. branous valve, which prevents the water from entering the ex1remit£S o/m n 1 nnTTf8 hX1:f8 " by - , , . believed correspond to the bilocular cone o? the higher In liiRDS, of the three semicircular canals the vertical classes. ^ is largest, and obliquely directed forwards and outwards; These membranous cavities are contained, in the bony the second ^horizontal and turned outwards; and the fishes, in the general cavity of the cranium; and while only thu d, which, like the first, is vertical, crosses the second, the middle of the canals is inclosed in the bone of the and is turned in the direction opposite to that of the first, cranium, the extremities and the sac are quite free. The e vestibule is small and nearly spherical. The bilocu- sturgeon, which belongs to the cartilaginous order is the ar cone, which is obtuse at the apex, is situate obliquely first in which the canals are entirely inclosed in the cra- backwards and outwards below the inferior part of the nial cartilage; but even in this a membrane is interposed cranium. Ihe longitudinal septum consists of two nar- between the cranium and sac, which is free. In the rav row cartilaginous plates connected by a thin membrane, and shark genera, again, these organs are entirely in? Ihe posterior canal is short, and, as m the Mammalia, closed in the cartilage of the head. ^ is separated from the tympanal cavity by the membrane of the fenestra rotunda; while the anterior, which is larger, communicates directly with the vestibule. The whole of these parts are inclosed, as in the Mammalia, in the compact bone of the pyramid The tympanal cavity, in like manner, is modified, and eventually disappears as we descend in the scale. Though present in the tortoise, crocodile, and lizard tribe, it is superficial and open; it becomes membranous behind in the Ranine tribe, and communicates directly with the The posterior and inferior ialls of the tympanal cavity back of the moulh rrod i 7 SeZ^/reXs U B formed bv part of the ncc n tn hnno • tho ’ , . , ,7 7: . lepuies 1C are formed by part of the occipital bone ; the lateral aper ture is large, and the cavity superficial; and its anterior pai t is closed by the posterior superior cornu of the quad¬ rilateral bone and a membrane. The inner wall presents the two apertures—the oval or vestibular, and the round or cochlear. In this class, however, while the upper is ympanal >nes dis- ipearing modi- •d. entirely disappears, so that the handle of the osseous plate by which the oval aperture is closed is suspended in the soft parts with its free extremity below the skin, near the articulation of the lower jaw. In the lizard tribe, also, Cochlear the round or cochlear aperture is seen for the last time, aperture munrl *>.; i .i i ' - —y “EE"'1 ^ 1° the Cheloniad, for instance, the Batrachoid, and the disaPPears- u" d v t ^ gU a1’’ the l°^er .1S distinctly elliptical,—a Serpentine, this aperture disappears, and the oval or ves- Fnstn'?11 I16! reverse of wbat 18 observed in man. The tibular alone is left; and in the salamander both disap-Vestibular seous The ?™ °r 7mpan°-guttural canal is entirely os- pear, and there is no communication between the external aperture consist- ympanal cavity contains only one ossiculum, part of the cranium and the labyrinth. This arrangement disaPPears- consisting of two branches ; the first attached to the tym- is continued in the fishes. g braTovTorTrhn"1,? t0 W ™?&M^.,tbe second closing . In the molluscous animals the labyrinthine membrane the^fn lang dar platf the vestlbular aperture, and is a simple sac, globular or ovoidal, containing pulpy matter By C “uZKuZhf t0 th7f7 °r thC Ma“ai7- “ Which is suspe'lded a sma11 body> "hich'L ZZTi ZiMateianir Pi ‘0 be represented ^ tlle th,e. and amylaceous in the many-feet (polypus), in ^ TKo . ?ie’ . , which the filaments of the auditory nerve are distributed ,Prmr!XS! Sh°r> and °Pened hy a simPle . 0ur bmits do not allow us to enter into the detailed | locular 1 ie disap aperture, while the absence of external ear is compensat ei y a ring or zone of fine elastic feathers with thin narbs, between which the air passes very easily. In the oh tube it terminates in a large cavity, the margins of winch are covered by a smooth valvular fold of skin. description of the organ in the other Invertebrated animals. SECT. IV. THE ORGAN OF TASTE. 1 hough the sense of taste is seated chiefly in the The pir nf • , ,, 71 UI hKm" inougn the sense of taste is seated chiefly m the pearance of the h-lEPT|ILES 1§ remarkable for the last ap- tongue in animals, yet that organ performs, in all the cular ann-iritne i1.0^11.31 con5'\ and first °f tbe sac" classes, so important a part as an instrument of prehen- codile md Vnar-A fV-1C 1 18 °Und m fishes. In the cro- sion, that it cannot with much justice be distinguished by ofa conical tnh v .V8 Part aPPears’as 1,n Birds, in the shape the former title only. In the present section, therefore, t, ivi eel by a cartilaginous partition into a we must regard it as one of prehension as well as of taste. 100 ANATOMY. Compara. In the Mammalia and Birds the tongue is a muscular live organ invested by mucous papillated membrane, supported - Anatomv Anatomy, a pr0per bone, the hyoid, which serves as a point of out suddenly, and become of a dark-blue colour at the support in its various motions. In the Ranine Reptiles moment of projection is in all probability found in several of the lizards, the Compara. tongues of which, like that of the chameleon, are darted hve Erectile arrange¬ ment in raffe. it is also muscular, attached to the margin of the lower jaw. In the salamander, however, it is attached as far as the tip, and is movable on the sides only. In the croco¬ dile it is attached so generally, both by tip and margins, that it was long asserted that the animal was tongueless. In the stellio and iguana it is as movable as in the Mam¬ malia ; and in the seine and gecko to this property is added that of being bifid, or divided by a longitudinal notch into two pointed tips. In the ordinary lizard, tu- pinambis, monitor, &c. the tongue is remarkable for its great extensibility, and terminates in two long, flexible though semi-cartilaginous extremities. That of the cha¬ meleon is still more extensible, and forms, by a peculiar arrangement of vessels, a cup-like extremity. The tongue of the blind worm (anguis fragilis) and amphisb&na is also bifid at the tip. The cartilaginous fishes are void of tongue, while in the bony division of the class this organ is represented by a hard protuberance, attached to the middle branchial bone. In some of the Mammalia, however, the tongue is not exclusively muscular. In the singularly long, extensi¬ ble, and tortuous tongue of the giraffe, Sir Everard Home describes a peculiar arrangement of vessels, which he re¬ presents as a substitute for muscular motion. Though Sir Everard does not appear to understand the exact nature of this arrangement of vessels, all the circumstances tend to the tongue S|10W tiiat it js that denominated erectile. These vessels, ot the gi- from tjie account given, are large, numerous, and com¬ municate freely; and it would be impossible to discover the reason of such a vascular system, unless for some purpose of this description. (Phil. Trans. Comp. Anat.) When the tongue is protruded it becomes perfectly black or bluish-black, evidently from the injection and detention of the blood in its elongated and anastomosing veins. By means of this mechanism the giraffe not only elongates the tongue to the distance of about twenty inches or two feet beyond the mouth, but twists it round the soft leafy twigs of the trees on which he feeds. It is not improba¬ ble that a similar vascular arrangement exists, though in less degree, in the tongue of the deer, and in the long projectile tongue of the animals of the ant-eater tribe, as the Tamanoir, Tamandua, &c. The erectile arrangement is still more distinctly pre¬ chameleon. sented in the tongue of the chameleon. The researches of Mr Houston of Dublin show that the tongue of this animal consists of two parts,—a prehensile, which is ante¬ rior, and provided with a glandular apparatus for secret¬ ing the viscid fluid by which its tip is covered, and in¬ sects are entangled; and an erectile, which is posterior between the prehensile and the hyoid bone, in the form of a trellis-work of innumerable minute anastomosing blood¬ vessels, not very dissimilar to those of the cavernous body in animals generally, and inclosing a central tube connect¬ ing the prehensile portion to the hyoid bone. The effect of this arrangement is, that when the vascular network is injected with blood, the anterior part of the tongue is ra¬ pidly darted out at the insects on which the animal lives. The injection of these vessels, and the consequent pro¬ jection of the tongue, is not independent altogether of the will of the animal; for the veins by which the blood is returned pass through a slit in the tendon of the internal cerato-maxillary muscles, which are always contracted in order to protrude the hyoid style, and thereby tend, by compressing the veins, to inject the erectile part, and pro¬ ject the tongue. (Trans. R. I. Acad. 1828, and Dublin 'Hospital Reports, vol. v. p. 487.) The same arrangement and of the In all the Mammalia the tongue is invested by a pa-Papillae pillated muco-villous membrane, in which the papillae are of the same general characters as in man—granular, mush¬ room-like, or fungiform, tubercular or calycoid, and conical or acuminated. The only differences consist in the size and abundance of the fungiform papillae, in the number of the calycoid and the mode of their arrangement, and in the shape of the conical papillae and the mode of their termination. In the Ruminants especially, the conical papillae are numerous, long, slightly incurvated, and each terminating in a horny but flexible style slightly incur¬ vated backwards. The tongue of the dolphin and por¬ poise, examined even by the microscope, presents no dis¬ tinct conical papillae, but is covered by minute eminences, each penetrated by a small aperture. In the tongue of the dog genus there is a ligamentous Worm of substance extended longitudinally from the hyoid bone to the dog; ns the tip of the member. This, which has been vulgarly absurdity- distinguished by the name of worm of the tongue, and has been absurdly supposed to be the seat of hydrophobic rabies, is merely a central pillar of support for the mus¬ cular fibres to act with greater steadiness and effect, and which enables the animal to protrude and expand the tongue in lapping water or other fluids better than he could have otherwise done. A similar central ligament is found in the opossum. The tongue of Birds is generally more or less homy, and almost cartilaginous. That of the woodpecker and wryneck is peculiar in consisting of two parts,—a basilar or posterior, loose and fleshy; and an anterior projec¬ tile, long, smooth, acuminated, and covered laterally with four or five stiff spines directed backwards, which make the organ a sort of barbed arrow. The soft, loose, or basilar part of the tongue contains the aperture of the glottis; and the surface is covered with minute spines pointed backwards, and each of which is placed in the centre of a fleshy papilla. As a prehensile organ of very singular construction, Trunk of the trunk of the elephant deserves particular notice; and ^ e)e* it cannot be more conveniently introduced than under the P an ' present section, since it is used not only to convey food, but drink, into the mouth. The trunk may be described as a cylindrical tubular organ, consisting of integument, a sort of fibro-cartilage, muscles, fat, and a membrane of villous character internally. This tube contains two long canals continued from the nostrils, parallel to the axis of the trunk, and separated throughout by a partition of adi¬ pose substance about two fifths of an inch thick. From the extremity to the middle part of the intermaxillary bone, in which the tusks are fixed, these canals are nearer the anterior-superior than the posterior-inferior part of the tube, the latter wall being thickest; and their diameter is the same throughout. At this part they undergo a sudden incurvation, approaching the anterior surface of the inter¬ maxillary bone, and form a semicircular bend with the convexity turned forwards. Here also they are so narrow that, without a muscular effort on the part of the animal to dilate them, fluids could not ascend beyond this point; and hence this forms the only valvular contrivance, either to impede the progress of fluids upwards, or to propel them downwards, at the will of the animal. Above this curvature each canal is dilated before the upper part of the intermaxillary bone, and again is con¬ tracted where it bends back to enter the bony nostril; and the curvature is protected before by the nasal cartilage, which is oval, convex in the male, and flat in the female. * ANATOMY. 101 Compara- Both canals are lined by a dry, greenish-yellow coloured t*ve membrane, marked with superficial intersections (rugce), Anatomy. incios;ng rhomboidal spaces, and some venous branches. 'TV Though the muscular fasciculi of the trunk are nume- nnaratus rous’ they may be referred to two orders,—those forming ,[• the the substance or inner part of the organ, and those by runk which it is invested. The former, which are transverse, lighly and cut the axis in different directions, consist of nume- omplicat- roug sma]i mUscular packets proceeding in various direc¬ tions, some running from the inner membrane to the cir¬ cumference of the tube, others directly from right to left, and others crossing the two former obliquely. All these little muscles are inclosed in cellular tissue, containing white homogeneous fat; and all of them terminate in slen¬ der tendons, some of which cross the layers of the longi¬ tudinal muscles in their course to the external covering, while others are attached to the internal membrane. Cuvier calculates the number of these minute transverse muscles in the trunk of the elephant to be not fewer than 30,000 or 40,000. (Plate XXXVII. fig. 13.) The longitudinal muscles, which are external, may be distinguished into anterior, posterior, and lateral bundles. The first extend from the anterior surface of the frontal bone, above the nasal bones and cartilages, in parallel bundles, connected by tendinous intersections downwards on the trunk. The posterior extend from the posterior surface and inferior margin of the intermaxillary bones, and form two layers which meet on the median line along the lower surface of the trunk. The lateral muscles form two pairs, one of which, descending between the anterior and posterior muscles to the middle of the trunk, may be regarded as a continuation of the orbicular muscle of the lips, or the representative of the nasalis labii superioris ; while the other, which is attached to the anterior margin of the orbit, and is expanded over the root of the former, may be supposed to correspond to the levator of the upper lip. The whole of these muscles are supplied by a very large branch of the infraorbital or second branch of the tri¬ facial nerve, which, entering on each side between the lateral and superior muscle, is distributed to the whole of the trunk. With such a construction, it is not difficult to under¬ stand the numerous motions of the elephant’s trunk. While the longitudinal muscles are employed either to shorten the tube, to bend it upwards or downwards or to the side, or by means of the tendinous intersections to give it peculiar inflections, it is manifest that the trans¬ verse ones, which act as antagonists to the longitudinal, may also either dilate or close the canals, or incurvate or alter the direction of particular parts. ^acuefy- The foot of the Lacerta Gecko and the house-fly pre- ng appa- sents a prehensile apparatus of peculiar construction for heUfeet 0fW.alking alonS surf'aces, n opposition to the action of gra- ertain v^y* In the former animal the plantar surface of each mimals. toe presents sixteen transverse slits, leading into an equal number of pouches, which by means of appropriate mus¬ cles are capable of forming an equal number of vacua, so that the atmospheric pressure is employed with muscular effort to support the animal in his unnatural position. A similar apparatus is found in the upper surface of the head of the sucking fish (echeneis remora); and something ap¬ proaching to it, though less distinctly, in the foot of the walrus. (Home, Phil. Trans. 1816.) CHAP. XV.—COMPAKATIVE ANATOMY OF THE ORGANS OF VOICE. „ Under this head our limits allow us to mention very few circumstances. In the American long-tailed monkeys (sapajous') the Mv. cuneiform cartilages form, by means of adipose cellular Compara- tissue, before the upper extremity of the ventricle of the ^ve glottis, a large cushion like a spherical segment, which, Anatomy, touching that of the opposite side, causes the air to whistle through the canal in its course to the mouth, and occa¬ sions the flute-like voice of some of these animals, as the weeper (s. apella) and the capuchin (s. capucina). In the Voice of howler («. seniculus), so remarkable for its morning and the howler evening yelling, though the larynx is similar in general aPe> characters to that of the common sapajou, in having the two rounded cushions before the ventricles, the hyoid bone is arched in the form of a spherical chamber, with a large quadrilateral aperture, and each ventricle opens into a membranous sac, lying between the epiglottis and the adjoining wing of the thyroid cartilage. The air, which passes between the vocal chords, is therefore partly im¬ pelled into this osseous and elastic cavity of the hyoid bone, and probably by its resonance in this situation gives the voice of these animals the deep-toned howl by which they are known in the American forests. Among the Zoophaga, in the dog the cuneiform carti¬ lages are large, the arytenoid small, the vocal chords well marked, and the ventricles deep. In the feline tribe the anterior ligaments, though destitute of cuneiform carti¬ lages, are thick, and separated from the back of the epi¬ glottis by a broad, deep furrow. The posterior ligaments, though neither free nor sharp-edged, are distinguished from the anterior by an appearance of greater firmness, more regular fibres, and by an intermediate furrow. The approximation of the anterior ligaments towards the glot¬ tis forms a sonorous vault, in which the air may be forci¬ bly vibrated by the posterior. In the bear the cuneiform cartilages assume the shape of styles, and their posterior extremity forms a distinct eminence, not above, but with¬ out the arytenoid cartilages, while the ventricles are merely deep fissures. The kangaroo has neither cuneiform cartilage, anterior ligament, nor ventricle; and it may even be said to be void of vocal chord, while the margins of the glottis are much separated in the middle. This arrangement appears to indicate that the animal is almost destitute of voice. In the opossum, in which there is merely a small infe¬ rior ligament susceptible of tension, voice is limited to a whistling sound. In the Solidungula, in which the cuneiform cartilages are completely concealed by the mucous membrane, there is neither superior ligament nor proper ventricle; but an aperture in the lateral wall of the laryngeal membrane, above the vocal chord, leads into a large, oblong, sinuous cavity, situate between this membrane and the thyroid cartilage, and covered chiefly by the thyro-arytenoid muscles, by which it may be compressed; and above the anterior commissure of the vocal chords, or below the base of the epiglottis, is an aperture on the mesial plane, leading into a cavity below the vault formed by the ante¬ rior margin of the thyroid cartilage. This cavity, which maybe named the infrathyroid, is superficial in the horse, of the ass, and its aperture is large; while in the ass, with a small, round aperture, the cavity is large, capacious, and globular in every direction, and allows the latter animal to make his voice re-echo in the singularly harsh sound denominated the brag. Conversely, though the lateral cavities are equally large in both animals, the apertures in those of the ass are small, round, and situate nearer the epiglottis than the vocal chord, while those of the horse are large, oblong, and situate immediately above the vocal chord on and horse, each side. On the latter peculiarity appears to depend the neigh of the horse. In the Cetacea we recognise neither vocal chords nor glottis, that is to say, an aperture variable in size ac- 102 ANATOMY. Compara- cording to the will of the animal; but the superior part fcive of the trachea, which represents the larynx, forms a hollow pyramid or funnel, rising into the posterior part of the nostrils, in which only it opens, while on the sides is left a passage for the food. This pyramidal funnel is formed by an elongated triangular cartilage, corresponding to the epiglottis, attached by membrane to the arytenoid carti¬ lages, which also take the shape of scalene triangles, with the small side connected to the cricoid cartilage. Strictly speaking, therefore, the Cetacea have no larynx, and probably no vocal organ; and the superior part of the trachea, with the nostrils, serves merely to admit the at¬ mospheric air for the purposes of respiration. Birds are distinguished by possessing not only a glot¬ tis or laryngeal aperture similar to that of the Mamma¬ lia at the upper end of the trachea, but a second, deno¬ minated the inferior glottis or larynx, at the lower end, near its bifurcation. The former, which is composed of four cartilages, or six, according as the cricoid consists of one or three pieces, on the middle of the posterior part of which is a small round bone, articulated with two oblong longitudinal bones, parallel, and forming between them in the posterior wall of the windpipe a longitudinal slit, sus¬ ceptible of approximation by means of muscles, is intend¬ ed merely to regulate the admission of air into the wind¬ pipe, or its expulsion from that tube, and to close more or less accurately its superior orifice. Inferior The inferior larynx consists of a membrane projecting or modu- from each side of the inferior aperture of the trachea. rvn'x’of * This aperture is divided into two, occasionally by an os- birds. seous anterior-posterior middle bar, occasionally by the angle at which the two bronchial tubes unite. Since the first bronchial arc has the same curvature as the last tra¬ cheal ring, the second and third, which are arcs of larger circles, are less convex without, but more prominent with¬ in, than the former. Over this prominence the tracheo¬ bronchial membrane forms a fold, which, half closing on each side the inferior tracheal aperture, forms a plate sus¬ ceptible of vibrating by the motion of the air, and produc¬ ing sound. This apparatus, which constitutes what is named the inferior larynx, or rather glottis, is of two kinds, one void of proper muscles, the other provided with muscles. In the former kind of larynx the state of the glottis is altered only by those muscles which depress and elevate the trachea. The depressors are two pairs, the sterno¬ tracheal and the glosso-tracheal, the latter attached to the bifurcated bone and trachea. There are no proper elevators; but the windpipe is raised by the mylo-hyoid muscle through the ligaments which connect the hyoid bone to the superior larynx. In the quiescent or relaxed state, and while the trachea is depressed, the bronchial rings approximate, and the second and third even gliding below the first, the glottis may be elongated. When the trachea is elevated by these pairs of muscles, the bronchi are at the same time dragged upwards, and the second and third arcs are separated from the first; and while the ex¬ ternal prominence of the glottidal membrane diminishes in length, its tension is augmented. These forms of larynx without proper muscles may yet be subdivided into two sorts, as they have or have not lateral pouches, membra¬ nous or osseous. These are observed in the male duck (anas') and the merganser (niergus), but never in the fe¬ male ; and to this perhaps the harsh and deep tone of the voice of the male bird is to be ascribed. The larynx without muscles and without pouch is observed in all the gallinaceous order without exception* The forms of larynx provided with proper muscles may be distinguished into three subdivisions. The first, which has only one proper muscle on each side, is observed in the whole of the falcon genus, e. g. the eagle, hawk, falcon, buzzard, sparrow-hawk, and goss- Compara- hawk; in the owl genus and the majority of the waders bve and swimmers, as the heron, bustard, woodcock, lapwing, ^atomy. rail, coot, gull, cormorant, and some of the passerine birds. In these birds, in which the motions of the lower larynx are necessarily limited, the voice is not variable or exten¬ sive in its notes. The second form of larynx has three pair of proper muscles, a constrictor of the glottis, an auxiliary constric¬ tor, and a laxator or opener of the glottis. This kind of larynx is observed in the whole of the parrot genus and psittacoid birds generally, as the toucan, macaw, calao, &c. In the third kind of musculo-membranous larynx there are no fewer than five pair of muscles, the longitudinal levator of the demiannular cartilages, the posterior le¬ vator of the same cartilages, the small levator, the ob¬ lique levator, and the transverse levator. This quinque- muscular larynx is found not only in all the birds proper¬ ly named whistlers or warblers, as the nightingale, hedge- sparrow, blackbird, thrush, goldfinch, lark, linnet, canary, chaffinch, &c., but in others whose tones are more mono¬ tonous, as the swallow, sparrow, stork, crossbill, &c., and even in some the tones of which are harsh and positive¬ ly disagreeable, e. g. the jay, magpie, crow, raven, &c. The differences remarked in the notes of these three divisions of birds with the quinque-muscular larynx de¬ pend not so much on anatomical peculiarities as on the timbre of their larynx, and on the mobility of the trachea in relation to the larynx, and on the tracheal membrane having dilatations and contractions. On the whole, the inferior larynx of birds is to be re¬ garded in three lights: ls£, As the reed of a wind-instru¬ ment, like a hautboy or clarionet, in which the notes vary as the lower glottis varies in its position to the wind¬ pipe ; 2d, as an instrument susceptible of uttering differ¬ ent tones, according to the distance between the mouth¬ piece and vent, or as the windpipe is elongated or short¬ ened ; and, 2>d, as an instrument capable of uttering dif¬ ferent notes by varying the diameter of the mouth-piece, or as the superior glottis is widened or contracted. The only bird in which the inferior larynx is wanting is the vulture. The vocal organ of the Reptiles consists of the supe¬ rior larynx only, analogous to that of the Mammalia. This is a cartilaginous apparatus, composed in general of five distinct pieces at least in the large individuals of the Saurial genera, as the crocodile and alligator, and form¬ ing a broad cavity behind, before a narrow slit, bounded by two vertical pillars. The glottis, however, is entirely membranous ; and there are neither vocal chords nor ven¬ tricles. There are nevertheless two muscles, one for opening and another for shutting the glottis. When these act, and the air is made to vibrate against the anterior pillars, it gives a slight whistling sound only. In the iguana, tupinambis, lizard, tortoise, and serpent, the ar¬ rangement of parts is nearly the same ; and these animals, therefore, can utter only slight hissing sounds. In the chameleon the pillars are furnished with a tense, vibrating membrane, a fleshy tubercle which contracts the glottis, and a membranous pouch opening below, between the lower laryngeal cartilage and the first tracheal ring. In the frog tribe, so remarkable for their croaking noise, the vocal chords are large and prominent. The males have also two membranous pouches, opening by a small aper¬ ture, not in the larynx, but deep in the lateral part of the mouth. When the frog croaks these pouches are inflated, and swell the skin on each side below the ear. Though these sacs are wanting in the female frog, and toad both male and female, as well as the tree-frog, there is beneath the throat a single pouch on the median plane. ANATOMY. Compara- chap. v.—comparative neurology. classes, in which the white matter progressively aug- Compara- ments. tive Anaton^ a general view of the nervous systems in different The sternal and dorsal longitudinal lines indicate the Anatoniy- classes of animals shows that the only common part is an original formation of the chord in two lateral portions, azygous tubercle, situate at the anteiior extremity of the with an intermediate cavity denominated the spinal canal, spinal chord, connected by means of two lateral bundles This exists only during the formation of the chord in the or peduncles to the rest of the system. This mass, which human foetus, in some of the Mammalia when adult, and corresponds to what is denominated the cerebellum in man, in the other three classes. Its disappearance in the hu- is connected in the vertebrated red-blooded animals with man foetus, and in that of various Mammalia, is repre¬ several pairs of tubercles, forming generally a larger mass seated by Serres to depend on the progressive deposition than itself, and connected to the rest of the system by of gray cerebral matter on the inner or central surfaces two longitudinal bundles or limbs, which mingle with and of the component pillars of the chord. Though obliterated intersect those of the cerebellum. These anterior-supe- in man, in whom the gray matter is abundant, it is not rior tubercles, which constitute the brain proper, present hermetically sealed in the monkey tribe, in which some numerous modifications in figure, disposition, and magni- traces of it are left. In the Amphibia and Cetacea it is tude, and even in presence, in the different orders of the larger than in the monkey tribe; its diameter augments animal world. _ . in the Carnivora, feline, canine, and ursine, in which the In the vertebrated animals the brain or central part of gray matter is thinner than in the former; and in the the nervous system consists of the vertebral or funicular Rodentia it is said to be largest of all among the Mam- portion, named the spinal chord, and the cranial or cepha- malia. Lastly, in the birds, reptiles, and fishes general- lie portion, properly denominated the brain. ]y, in which the gray matter is scanty and the white pre- ipinal I he funicular portion has the shape of a cylinder flat- dominates, the spinal canal is large and distinct. iiord. tened on its superior or dorsal and inferior or sternal The lateral regions of the spinal chord are connected surfaces. It consists of two similar chordiform produc- with a double series of nerves by means of two rows of ner- tions, united on the mesial plane, and marked at the line vous filaments, an anterior and posterior, separated by a of junction by linear longitudinal furrows, of which the longitudinal membrane of fine white tissue, with a serrat- superior is most deep and distinct. This, however, which ed or festooned border. This membrane, which is named was observed by Blasius in several animals, is denied by the denticulate, is the same in the Mammalia and Birds. Bellingeri, who asserts, from various observations, that That these nerves do not issue from the spinal chord, must though in some parts the superior furrow penetrates more be inferred not only from the phenomena attending the deeply than the inferior, in the general course of the chord original developement of the nervous system, but especial- the latter is the deepest. ( De Medulla Spinali Annota- ly from what is observed of their comparative size, and tiones Anatomico-Physiologica;. Auctore C. F. Bellingeri, that of the chord in the inferior classes. In that of fishes Aug. Taurinorum, 1823.) This discordance appears to especially, while the chord is small and slender, and by depend on the circumstance that the sternal or inferior no means fills the vertebral canal, it is remarkable that furrow is in truth deeper and more distinct in man, the the nerves which supply the voluntary muscles are ex¬ monkey tribe, and a few Mammalia, than the dorsal; ceedingly large. Thus, in many both of the cartilagi- whereas in most others, as the coati, raccoon, horse, &c. nous and osseous divisions, as the sturgeon, dog-fish, ray, the dorsal furrow is of the same depth as the sternal; and wolf-fish, cod, &c. the nerves which supply the pectoral in the mole, murine, and leporine genera, it is deeper and fins are large, broad chords, two or three of which seem more distinct than the sternal. In Birds and the carti- to contain more substance than the whole spinal chord laginous Fishes the sternal furrow is deepest; in Rep- itself. tiles the dorsal and sternal are nearly equally deep ; and in The chord is expanded at its cephalic end into a thick Bulb of the the osseous Fishes the dorsal is the deepest. On each side eminence denominated the spinal bulb, the surface of chord, of the chord, also, there is a slight longitudinal depression which presents three pairs of eminences. These eminences commonly called the lateral {sulcus lateralis). are developed in various degrees in the different classes The breadth and thickness ofthe spinal chord vary in dif- and orders. In some of the Mammalia the anterior ferent regions. The lower cervical portion is in general the pyramids or pyramidal bodies are more distinct than in broadest and thickest; at the upper dorsal region it is some- man, for instance the ape tribe, the Cetacea, Carnivora, what more slender,becomingthicker again at the lower dor- Ruminants, and Rodentia. They are small in most sal region; and after again becoming more slender in the Birds, all the Reptiles, and the Cartilaginous Fishes. In lumbar region, it is expanded into a filamentous brush-like the osseous division they assume the appearance of two termination ofdifferent lengths indifferent classes, and even parallel chords at the base ofthe brain. The olivary in different orders. These enlargements at the superior bodies, less prominent in the ape than in man, are still less dorsal and lumbar regions are believed by Serres to cor- so in the Cetacea, and progressively through the Amphi- respond with the origins of the thoracic and pelvic extre- bia, Carnivora, Ruminantia, Rodentia, and Insecti- mities ; and each swelling he represents to predominate vora, and the other three great classes of vertebrated ani- over the other, as the animal habitually employs the one mals. Conversely, the restiform bodies or posterior pyra- or the other kind of members. It is remarkable in illus- midal eminences, from man through the ape tribe, the tration of this principle, that in the Cetacea, which are Cetacea, Amphibia, to the Ruminants, Carnivora, void of pelvic extremities, the lumbar enlargement is and Rodentia, increase in size. wanting ; and in the amphibious Mammalia, the pelvic Though the brain of the Mammalia presents the same extremities of which are feeble, this enlargement is also parts, and is arranged nearly in the same order, as that of inconsiderable. man, it varies in its proportions to the rest of the body; 1 he spinal or funicular brain consists of white cerebral in its proportions to the cerebellum and spinal bulb; in ge- matter on the surface and gray matter in the centre, the neral figure ; in the presence, absence, and number of con- former being most abundant, unless in the sacral region, volutions; in the configuration of its central surface; in where both are nearly equal in quantity, or the gray rather the communication of its central with its external surface; predominates. In the Mammalia the gray matter is in and in the manner of its connections with the cerebral greater proportion to the white than in the other three nerves. As it is impossible in this sketch to examine all 104 ANATOMY. Compara- these circumstances fully, we shall confine our attention is marked by transverse parallel strise corresponding to Compara- ^ve to the notice of a few only. the lamina of the mammiferous brain. There is neither tive Anatomy, jj. js not eaSy to ascertain the proportion of the mass of middle band {corpus callosum), vault, nor septum. The V ^ v' the brain to that of the rest of the body. Excluding as ceiling or vault of the aqueduct or passage from the third W'Y'W much as possible the ordinary sources of fallacy, in small to the fourth ventricle is not, as in the Mammalia, sur- animals the brain is proportionally larger; yet in this mounted by the bigeminous eminences, but is merely a respect man is surpassed only by a small number of ani- thin plate corresponding to the valve. Each optic emi- mals, habitually lean, and with little muscle, as bats, small nence contains a cavity communicating with the others birds, &c. While the proportion of brain in man to that by the Sylvian aqueduct. The anterior eminences (cor- of the whole person varies from a 22d to a 35th part, pora striata) are not striated with alternate white and gray that of the monkey tribe varies from a 22d to a 42d part; matter, as in the Mammalia. Between the anterior and and in the baboon it is only the 104th part of the body, the optic eminences are four rounded tubercles, best seen Among the Mammalia, the Rodentia have in general in the ostrich, which are to be regarded as entirely hete- the largest proportion of brain, and the Pachydermata rologous to the structure of the mammiferous brain, and the smallest; and while the hare has a brain about the connecting the cerebral structure of Birds with that of 300th part of the size of the body, that of the elephant, Reptiles and Fishes, in which also these tubercles are ob- the most sagacious of animals, is about the 500th part the served. size of his body. It is also remarkable, that while the brain The Reptile brain is smooth and unconvoluted. The of the horse is only a 400th part of the size of his body, optic eminences, which are situate behind the hemispheres, that of the ass amounts to a 254th part. The Reptile brain are uncovered, and contain a ventricle communicating becomes excessively small, that of the turtle being rather with the third. At the extremities of the latter are the more than the 5000th part t>he size of his body; and anterior and posterior commissures, but there is neither in some of the Fishes, not all, it appears to attain the soft commissure nor bigeminous eminences. The hemi- maximum of decreasing proportion, that of the tunny be- sphere presents an anterior eminence, which, however, in ing so small as the 37,000th part of his body, while the the brain of Birds is unstriated. The cerebral valve is, brain of the carp is so large as to approach the proportion like that of Birds, unsurmounted by bigeminous emi- of the elephant. It may be doubted whether, under such nences. circumstances, any precise conclusions can be drawn from In the class of Fishes the structure becomes still more results so variable and so little to be expected. simple. The tubercles of which the brain consists are The proportional weight of the brain to that of the cere- placed in a row ; and their increase in number only de- bellum is, excepting in the case of one species of ape, the monstrates the decomposition of the organ, and its reso- saimiri, greater in man than in any other animal. The lution into simple integrant parts. The two representing ox is equal to man in this respect, and the dog approaches the hemispheres are ovoidal, unconvoluted, and contain a him. The animals most remote are the Rodentia, as ventricle, in which is seen the eminence analogous to the the beaver, rat, and mouse, &c. striated bodies. The optic eminences, situate beneath The convolutions, which are so numerous and so deep the hemispheres, though small, contain each a cavity, as in man, diminish both in number and size in the Quad- in the two oviparous classes already noticed. Lastly, rum an a and Carnivora, and are nearly obliterated in there are in several genera, under the common vault of the Rodentia. In the Ungulated animals, however, the hemispheres, occasionally two, occasionally four tu- and especially in the Ruminants and the horse, the con- bercles, variable in shape and proportions, but which volutions are numerous; and even in the dolphin among would be analogous to the bigeminous eminences, were the Cetacea, they are numerous and deep. In all the they not, like those already mentioned in Birds, situate Mammalia the cerebellum is foliated. before and above the optic chambers. In the cartilagi- On the whole, the peculiar character of the brain of nous fishes, in which these tubercles are not observed, man and the ape family consists in the existence of the the anterior or striated eminences are obliterated. The posterior lobe and digital cavity. The brain of the Zoo- cerebellum does not cover the fourth ventricle. phaga is remarkable for the small size of the nates or Behind the cerebellum are two tubercles, which in the anterior pair of the bigeminous eminences in proportion ray give origin to the fifth pair, and are very distinct in to the testes or posterior pair. In the Rodentia the or- the pike, trout, salmon, and perch. These tubercles are gan is distinguished for the large size of the nates, and peculiar to this class. the want or superficial nature of the convolutions. In the The cavities in the interior of the optic eminences in Ungulated division of animals, i. e. Pachydermata, Birds, Reptiles, and Fishes, are observed in the foetal Ruminantia, and Solidungula, the brain is remark- brain of the Mammalia during its early growth, able for the large size of the nates combined with the It is almost superfluous to mention, that, in the two number and depth of the convolutions; while that of the warm-blooded classes, Mammalia and Birds, the brain, Cetacea is remarkable for its height and breadth, and with its investments, fills completely the cranial and verte- the want of olfactory nerves. It is further to be observed bral cavities. In the Reptiles, however, in which the brain as a general distinction between herbivorous and carni- does not approach the cranial walls, we remark the first vorous or zoophagous animals, that in the former the nates departure from this arrangement; and in the Fishes it is so are larger than the testes, whereas in the latter the testes completely violated that the brain and chord occupy but a are largest. Lastly, Man and the Quadrumana are the small proportion of the cranio-vertebral cavity; and be- only animals which possess genuine olfactory nerves. In tween the former and the osseous walls there is a quantity the other quadrupeds they are represented by the mam- of fine but very loose filamentous tissue, containing in its miliary processes of the ancients; and in the Cetacea cells a large quantity of pellucid fluid. Though this ar- they have not yet been unequivocally demonstrated. rangement gives this the appearance of a white jelly-like The brain of Birds is at once recognised by consisting substance, it is not gelatinous, as is generally represented, of six distinct tubercles, two representing the cerebral but merely a pellucid fluid, sometimes pale straw-coloured, hemispheres, two representing the optic eminences, one occasionally with a reddish tint, contained in numerous the cerebellum, and one the bulb of the chord. The communicating cavities of a tissue which appears to repre¬ hemispheres are void of convolutions, but the cerebellum sent the arachnoid of the warm-blooded animals. ANATOMY. Compara¬ tive \natomy. 105 Ine of th. 1 irv df ' ereitt :>! mals. Thepia mater in the reptiles and fishes is reduced to a nerves of the Mamvtat x* j ■ j ^ filamento-vascular web, accompanying the blood-vessels. tributed to the mn«el^ c’fV, secon(^’ slender, are dis- Compara- The dura mater undergoes some peculiar modifications the " °o • ? t0ngUe ^ the, SUrfaCe °f a T" in different orders. In the duckbill a bony plate is con! whicTIravwse' ,b„ l! J =“ '^ge nerve ^omy. tained between the lamina! of tile falx; and the same neath the lateral line ° Z. on®ltuli'.nally immediately be- structure is found in the porpoise, perhaps in the other Wrds, reptiles a„d fishes P ”erVe 'S Want'”g m Cetacka. An osseous tentorium with a quadrangular In Oxi iUex’xT„ xi/ aperture is found in the coai'ta and marten, and the feline numhpr nf x 1 v iSCA le neivous consists of a and ursine families ; and an osseous partition consisting of parts of the hodv C?.r]ebra ma®ses distributed m different three parts is found in the dog, horse, Cape ant-eater K thf a l y’ a T Z tW° m°re consPicuo»8 than teropm), the wombat, and the seal. The bony SiS nladd Un SUPF°Sed t'Verefore !° rePrele.nt th and expanded a few words must suffice. In fishes the tenth or pneu- Thefirstofthl? wh° orenlargements. mogastric consists not of a common trunk, but of ^hree rarelv exrpprk thP’ntT 11C • 1S- SltuaJe on tbe oesoPbagus, orders of filaments, the first and largest of which are dis- hithert o pvaml A ttlerS m S1Ze‘ AmonS the Zoophytes tributed to the gills, and correspond to the pulmonary -d^ aSSUmeS & PART II. COMPARATIVE ANATOMY OF THE ENTROPHIC ORGANS. CHAP. I. THE LIMITROPHIC ORGANS.-SECT. I. THE ORGANS OF DIGESTION.-§ 1. THE TEETH. Though genuine teeth are found in three classes of ani¬ mals only, viz. the Mammalia, the Reptiles, and the Fishes, yet all the orders of these classes are not provid¬ ed with teeth. Thus, among the first class, the ant-eater tribe, the pangolin, the echidna and ornithorhyncus, and the whales—among the second the cheloniads—and among the third the sturgeon—are altogether destitute of these organs. In all the invertebrated classes, the jaws, when present, are provided with notches varying in number. The echinodermata alone have genuine teeth, inserted in a mechanical apparatus very different from ordinary jaws. Though in general structure the teeth of the lower ani¬ mals resemble those of man, in some respects they differ considerably. These varieties consist either in some change or modification of the constituent parts of the teeth, or in the addition of some other substance to those parts. The first variety to be noticed is of the former descrip¬ tion. 1 Though in the Quadrumana and Zoophaga the bony matter of the teeth is quite similar to that of man, in other orders this substance appears in the form of a very hard, compact, and more regularly fibrous substance than bone, and to which the name of ivory (ebur) is applied. It is chiefly in the canine or tearing teeth that this sub- stance is found to represent the bony pillar of the teeth; and it is principally among the Pachydermata, and some of the Amphibia and Cetacea, that this change is ob¬ served. The ivory of the elephant is the most tender, and that w ic i most rapidly becomes yellow on exposure to air. it is readily distinguished from the ivory of other animals y the curve lines which radiate from the centre to the cncumference of the tooth in various directions, and which 0r,TTi ^ ln^erseict*on regular curvilinear lozenges. f he ivory of the hippopotamus is greatly harder and v ii er, and is on that account preferably employed for ic preparation of artificial teeth. A transverse section , 18 8ubst»nce shows stria} extremely delicate and re- ?.r: n t us animal, also, not only the canine but the e6i 1 coj181st of this substance. The tusks of the that nc'fiL i°ar SUS Ethiopians) consist of ivory similar to .u , le ^‘Ppopotamus. In those of the ordinary boar, t, no s nee are recognised, there is sometimes a mix- vul. ih. ture of brown substance disposed in layers. The ivory of the teeth of the morse, though void of stria;, is compact and susceptible of polish nearly as brilliant as that of the hippopotamus; and its character is, that the central pillar of the tooth consists of minute round grains, indiscrimi¬ nately aggregated, like pebbles in puddingstone. The axis or pillar of the molar teeth of this animal, which are without internal cavity, consists of similar minute grains. The ivory of the dugong is homogeneous and without stri(E. I hat of the teeth of the white whale or cachalot resembles the bone of human teeth in its satin-like ap¬ pearance. The ivory of the tusk of the narwal is very compact and homogeneous in appearance. The most singular structure of teeth among quadrupeds is observed in those of the Cape ant-eater (orycteropus). I he teeth of this animal, which have the appearance of two cylinders conjoined, consist of an infinite number of minute straight parallel tubes, so that their transverse section resembles that of a rush. As these tubes are closed only at the triturating surface, it is there only that the tissue of the tooth is compact; and when the enamel is worn, the upper orifices of these tubes begin to be exposed. There is, therefore, no general cavity in the in¬ terior of the tooth. These teeth are also void of root. A similar tubular structure is observed in the two molar teeth of the ornithorhyncus, and in the teeth of some fishes. The enamel {lamella vitrea, cortex stnatus) presents Enamel, peculiarities in the lower animals, as well as the bone of the tooth. While the enamel of the human tooth is confined to the crown, in several of the lower animals, as the morse, it envelopes the tooth all round; and in the molar teeth of. this animal, which, indeed, are void of cavity, it is thicker under the root than at the crown. A similar ar¬ rangement is observed in the old or adult teeth of the cachalot, which, when their cavity is obliterated by the full deposition of osseous substance, are also covered with enamel below. The texture or constitution of the enamel is best seen in the grinders of the elephant. The section of a tooth in the germ exhibits fibres similar to those of asbestos or fine velvet. The fracture of the enamel is more dis¬ tinctly fibrous than that of the bone, and the fibres are everywhere perpendicular, or nearly so, to the surface of o 106 ANATOMY. Compara¬ tive Anatomy. Simple teeth. Compound teeth. Semiconi' pound t-eth. The ce¬ ment or crusta petrosa. the tooth. The hardness of this substance may be in¬ ferred from the fact that it strikes fire with steel. These component fibres, however, are not always rectilineal. Most frequently they describe curves with the convexity of incurvation towards the crown and the concavity to¬ wards the root. This arrangement at least is observed in the ruminants. The distinction between the enamel and bony matter is recognised by a gray line, and another whiter which belongs to the latter substance.. The enamel varies chiefly in thickness in different ani¬ mals. The tusks which project from the mouth are ge¬ nerally observed to be less white, less hard, and more similar to bone or ivory than the other teeth ; and on this account, probably, the existence of enamel has been de¬ nied in the tusks of the elephant. It is nevertheless cer¬ tain that the external layer of these tusks presents radiat¬ ing fibres, though it is by no means so hard, or possesses the same grain, as the enamel of the other teeth. Enamel is more apparent, though thinner, in the tusks of the morse, dugong, and boar; and it is quite as distinct in those of the hippopotamus as in the other teeth of that animal. Lastly, the enamel of the teeth of the cachalot, which is very thick, shows in its section only strice paiallel to the surface of the osseous substance. Teeth may be distinguished according to the mode in which their component tissues are arranged into three sorts. ls£, When the enamel invests the axis all round, and does not penetrate the latter, the tooth is said to be simple (dens simplex). Such is the character of the human teeth, and those of the Quadrumana and Zoo- phaga, and several other animals, and all the reptiles. 2d, When the enamel is folded as it were round the bony part, but without inclosing it, so that the latter forms a continuous band several times folded on itself, and sec¬ tions of the tooth in every direction divide repeatedly the component substances, the tooth is said to be compound or complex (dens multiplex vel compositus). A good exam¬ ple of this structure is seen in the grinders of the ele¬ phant. 3c?, When the base or root of the tooth is simple, and the folds of the enamel and bone penetrate only to a certain depth, they are said to be semicompound. Ex¬ amples of this modification of arrangement are seen in the grinders of the ruminating animals. In the compound, and part of the semicompound teeth, the enamel is covered by a third substance; and as the latter is arranged, especially in the former sort, so as to leave intervals between it and the next layer of enamel, this substance serves to fill all these intervals, and conso¬ lidates the component lobes of the tooth even before their osseous parts are united below. This substance, which is denominated by Cuvier cement, by Tenon cortex osseus, and by Blake crusta petrosa, though less firm than either bone or enamel, is dissolved by acids more slowly than the former, and sooner becomes black in the fire. In the teeth of the elephant and cabiai it forms half their mass at least. In most genera it presents no apparent organiza¬ tion, and resembles a sort of crystalline tartar incrusted on the tooth. In the cabiai, however, it presents nume¬ rous pores very regularly arranged. Tenon was of opi¬ nion that it arose from ossification of the membrane which enveloped the tooth ; blake ascribed it to deposition from the opposite surface of the enamel membrane; but Cuvier ascertained that it is deposited by the same membrane and the same surface as the enamel. This accurate observer found, on inspecting the germs ot the teeth of the elephant, that when the internal membrane of the dental capsule has deposited the enamel, it undergoes a change of structure, and becomes thick, spongy, opaque, and reddish, to furnish the cement, which is then deposit¬ ed, not in regular crystalline fibres, but in random drops. The teeth of the Reptiles consist of hard, compact, os- Compara. seous matter, invested by a thin covering of enamel, and without cement. . The teeth of Fishes vary much m structure. They are Teeth of either simple or compound. The simple teeth are those gshe& which consist of bone invested by enamel. They may be distinguished into two species, according to their mode of attachment. The first are the simple teeth, which are not implanted in alveoli, but merely attached to the gum, or fixed by articulation to the jaw, as those of the shark tribe ; the second are simple teeth growing m alveolar cavities, as is observed in the majority of fishes, the pike, dory, &c. The simple teeth attached to the gum are chiefly distinguished by their fibres intersecting in the manner of the cancellated tissue of bones, and being therefore at first light, porous, and spongy, and becoming afterwards uniformly hard and compact like ivory. The compound teeth, which consist of an infinite num¬ ber of minute tubes mutually aggregated and invested by a common covering of enamel, form plates of different sizes, adhering to the bones of the jaws or palate by an intermediate membrane only. In some they affect the disposition of the quincunx; in others they occupy the whole breadth of the upper jaw at least, as in the ray as seen on the small scale, and in the same manner in larger fishes ; others are in straight transverse bars ; others as¬ sume the shape of a circular segment, or the figure in heraldry denominated the chevron. In the wolf-fish the jaws are provided with eminences composed of fibres or tubes proceeding from the base to the circumference, and which are connected to the jaw by a substance more spongy than the rest of the bone. After their first formation the teeth retain nearly their Mecham. original shape in the Zoophaga, man, and the Quad-cadetri rumana. In the two latter only their crowns begin to be worn, rendering the incisor and canine less pointed by the use of food partly vegetable; but in the zoophagous tribes they undergo no detrition whatever. In the herbivorous animals, however, the crown begins to undergo detrition more or less rapidly; and in no long time the superior layer of enamel is entirely worn off, and the surface of the tooth exposes the succession of bone or ivory, enamel, and cement. These substances are well seen in the teeth of the Rodentia, for instance the hare; those of the Pachydermata, as the elephant; the Ruminants, as the stag, sheep, and ox ; and the Solidungula, as the horse. In all these animals the enamel, which is hardest, forms prominent lines or ridges; while the bone and cement are indicated by depressions. This detrition, which is purely mechanical, might pro¬ ceed to such an extent in the herbivorous quadrupeds as to destroy the whole of the crown of the tooth, and leave the process of mastication to be performed by the jaws only. It appears to be chiefly to obviate this incon- venience that the dentition of the elephant, the Ethiopian uc^.e.*n boar, and perhaps all the Pachydermata, is conducted in a successive manner through a series of six or eight ejephani sets of teeth at least. In the former animal, in which this process has been best observed, and was ably explain¬ ed many years ago by Mr John Corse Scott (Phil. Trans. 1799), each half-jaw, whatever it contains, exhibits at one time only one complete grinder and part of another behind it, the prominent parts of which are placed ob¬ liquely to the horizon, forming an inclined plane, so that the anterior parts are worn before the posterior. The anterior complete one, which is employed in mastication, undergoes progressive detrition till its anterior portion is worn down to the level of the jaw. In this state the fangs of the anterior part of the tooth begin to diminish, render¬ ing the tooth narrow before ; while the crown of the poste- 1 ANATOMY. Compara¬ tive Anatomy. 107 °ntition the rse. shc±,:bmoeuLte„rsst,,e next at "'e2oth’ °"dc™r- rn hryei is ad™nS^the ^ ™ ^ -S \sireTXsteor.af — Aniz. of which only the anterior part was appearing above the about the 11th month, and the second 7n the 9nthP At ' ^ gum, gradually rises, with its crown forming a plane in- the 30th or 32d month the first twn Zw •2°ih' A dined from before backwards, similar to that of the ante- shed, the third in the 3d year - and ah^ fu rior grinder. When this posterior tooth has been raised year the last posterior gri/der ^oears Th •r i6th sufficiently to allow its anterior margin to be used in mas- are longer from before backwards tha^ th!™^ grinderJ tication, the residue of the anterior tooth drops out al- ones, wldch are themselverc”traeted“„thtLPdl"eHr„ together, and the postenor one continues to rise and ad- as they are pressed by the posterior grinders; from whTch it results that the dental crowns of young horses are ob¬ long, while those of the old are quadrangular. In the Mammalia the teeth are always implanted in the jaw-bones, and never, as in other animals, in the tongue, palate, &c. The only exception to this rule is the echidna. dhe three kinds of teeth, incisor, tearing, and grinder, Arrange, are found together only in Man, the Quadrumana, themeilt of Zoophaga, the Pachydermata except the elephantthe teeth- and two-horned rhinoceros, in the hornless Ruminants, and in the Solidungula ; but, of all these animals, in man only are the three forms of teeth arranged in an unin¬ terrupted series, and in such a manner that those of the lower jaw are applied to those of the upper. In one other animal only, now extinct, the anoplotherium, is this conti¬ nuity of arrangement observed. In the Quadrumana and Zoophaga, and all those in which the canine are larger than the other teeth, there is a gap on each side of the jaw to receive the canine of the opposite one. In the ursine genus there is a large empty space behind each canine tooth. In the hedgehog, shrew, phalanger, and tarsier, in which the canine are shorter than the other teeth, a space is left between them and those opposite. In the maki tribe, proper bat, colugo, and camel, there is a large interval between the upper incisors. Last¬ ly, the Ruminants want the incisors of the upper jaw, and the morse those of the lower. Some animals provided with the three classes of teeth sists nf fi nr Q i.i lose the incisors at a certain age ; for instance several of sists of 8 01 9 plates, is completely exposed at the age of the bat tribe, and the Ethiopian hog. Other Mammalia k vLTTt £ .1 C,0TlnS f,,12 or,13 l>lates' a‘ have “"'y t™ sort* of teeth, for h,stance incisors and six years. _ I he fourth to the eighth grinder consist of grinders, separated by an interval without canine, as the at whJhT1^ 7 n!Tber T 10 t0 23,; but the pen0d wombat and a11 the Rodentia, in which there are only at which these teeth appear has not yet been determined. 2 incisors in each jaw; the kangaroo, which has two be- dip^uyjmr88/138'!^66'1 s !°wn to h^ve taken place also in low and 6 or 8 above; and the cavy or h/rax genus, gigantic fossil animal named the mastodon. _ which have 2 above and 4 below. The elephant has grind- Pro.cess of displacement and renovation takes ers and two tusks planted in the superior intermaxillary 1 < t n e poison-teeth of serpents, and m the teeth of bone, but no inferior incisors or canine teeth, the shark, diodon, and tetraodon tribes. In the wolf- Animals may possess grinders and canine teeth with- sh (anarrhicas lupus) the teeth are shed along with the out incisors, as the sloth tribe and the dugong. The spongy membrane in which they are contained, exactly ' 1 s - as the horns of the stag. In the horse, in which the process of dentition has been carefully observed, it is usefully employed to determine the age of the animal. The milk incisors appear at the end of 15 days; the four middle ones, or the nippers, are shed at 30 months; the four following ones at 42 months; and the four external, or the corner teeth, at 54 months. Ihe permanent corner teeth do not grow so quickly as the other incisors ; and by these especially the age of the horse is determined. At first they scarcely rise above the jaw. Their middle then presents a hollow dnTn V!lt ;iblackisu tartar’ the margins of which are worn uy pmtes ui me laminatea, nnrous, m . S., t00th nso? from the gum, and is rubbed tinguished by the name of w/ia/e-iowe. he corresponding one ; and it diminishes pro¬ gressively from 54 months to 8 years, when it is alto- get ier obliterated. The hollow of the other incisors is obliterated at a later period than that of the corner ones; and the age of the animal is then estimated from the length of the incisors, which continue to increase. 1 ie first two molar teeth appear in each jaw and on vance rapidly, until it is completed, when it is found to be much larger than the previous tooth, and to consist of a greater number of plates of ivory and enamel (denticuli). In no long time this new tooth, which undergoes the same process of detrition, is succeeded by another one, the anterior margin of which rises first behind the poste¬ rior one of its predecessor, and which passes through the same stages of growth, detrition, and shedding. This pro¬ cess is repeated at least seven or eight times, and each succeeding tooth is larger, and contains a greater number of ivory and enamel plates than its predecessor. The elephant has thus 7 or 8 grinders in each half-jaw, or 28 or 32 grinders respectively; yet there are never more than one tooth and part of another, or at most two, that is, eight teeth in the upper and lower jaws, at the same time. Though the disappearance of the fangs of the an¬ terior tooth is ascribed to absorption—which indeed is a good general name—yet the true reason is the fact that the maxillary or dental vessels of the elephant are unable to sustain more than one tooth in each half-jaw at once; and that since these vessels gradually transfer their blood to the new tooth, while those of the old one shrink and are obliterated, as the new tooth grows the old one is actually dehematised or atrophied. The order in which the teeth of the elephant succeed each other is nearly the following. The first or milk grinder, composed of 4 eburneo-vitreous plates (denticuli), cuts the gum eight or ten days after birth, is well formed in six weeks, and completely out in three months. The second, which con- grinders, which are most essential, are most rarely want¬ ing ; and when others are deficient these are present, as in the armadillo tribe, the orycteropus, the ornithorhyncus, two-horned rhinoceros, and lamantin. The jaws of the dolphin are provided with uniform conical teeth all round, while the cachalot or white whale has them in the lower jaw only. In the narwal there are only two long spiral tusks implanted in the intermaxillary bone, and of these one is often wanting. Lastly, teeth are entirely wanting in the ant-eater tribe, Absence of pangolin, and echidna, which are therefore arranged among the teeth, the Edentata. In the whale the teeth are represented by plates of the laminated, fibrous, bluish substance dis- " 1 1 ' y tiie name of whale-hone. § 2. ORGANS OF INSALIVATION. Under this head ought to be noticed the modification which the salivary glands undergo in the lower animals. Our limited space, however, obliges us to proceed imme¬ diately to notice the peculiarities of the other divisions of the alimentary canal. 108 Compara¬ tive Anatomy. CEsopha- gus. ANATOMY. Stomach. Simple stomach. Bilocular stomach. § 3. (ESOPHAGUS, STOMACH, AND INTESTINAL TUBE. The muscular tissue of the oesophagus consists, in most of the Mammalia, of spiral fibres twisted in two opposite directions, the external from before backwards, the inter¬ nal from behind forwards. This arrangement, which was first observed in the Ruminantia, was supposed to ex¬ plain the process of rumination. This opinion, however, is refuted by the fact that the arrangement is not con¬ fined to this order, but is very general among the zoopha- gous and other animals which do not ruminate. In the kangaroo the direction of these fibres is, as in man, trans¬ verse in the internal layer, and longitudinal in the external. The oesophageal mucous membrane is covered by epi¬ dermis, which extends to the cardiac opening of the stomach in man, the Quadrumana, and all the Zoopha- ga. This membrane, as well as the mucous, is thrown, by the action of the muscular tunic, into longitudinal folds, which are effaced only when the oesophagus is distended. In the tiger, lion, and lynx, there are large transverse val¬ vular folds, and smaller ones in the civet and couguar— an arrangement connected probably with the carnivorous habit. The stomachs of the lower animals vary considerably in shape, in the insertion of the oesophagus, in the disposi¬ tion of their muscular tunics, and in the simplicity or complication of their cavities. These characters it is im¬ possible in such a sketch as the present to consider in de¬ tail ; and we shall confine our attention to those peculiari¬ ties which are most striking in the digestive organs of the animal world. The stomachs of the Mammalia may be distinguished into the simple and compound. Those of man, the Quad¬ rumana, zoophagous and most of the herbivorous tribes, belong to the former order. This simple form of stomach, however, may be generally distinguished into two parts, a cardiac and a pyloric, more or less separated from its other by a central transverse contraction of its annular muscular fibres. This is particularly seen in the horse, man, murine family, and many other animals which occa¬ sionally feed both on animal and vegetable matter. In the human stomach this contraction is represented in Plate XXXVI. fig. 4. In the porcupine, however, there are three pouches. This contraction depends on a strong annular band of muscular fibres at this part of the organ. In the pure carnivorous animals, however, as the feline family, the annular fibres, which are very thick, are nearly equally so from the cardiac to the pyloric end. The compound stomachs, or those which contain more cavities than one, are found in the sloths, and the ruminant and cetaceous animals chiefly. In the first tribe the stomach of the Unau, or two-toed sloth, is two-fold. The first cavity is large and globular, but tapering behind into a conical appendage, separated by a semilunar fold ; while a large cul de sac on the left of the cardia opens into a canal which proceeds at first back¬ wards, and then turning to the right, enters the second cavity by a narrow aperture. The second, which is small, tubular, and folded under the former from left to right, is distinguished by a semilunar fold into two halves, the first of which opens into a small cul de sac on the right side of the first cavity. The inner membrane of both cavities is smooth, and without villi. A similar arrangement is found in the Ai, or three-toed sloth, with this exception, that the appendage of the second gastric cavity is divided into three compartments by two longitudinal bands. This ca¬ nal seems analogous to the arrangement of the ruminating stomachs, in so far as it may allow the alimentary matters to pass occasionally from the oesophagus directly into the second stomach. The stomach of the hxjrax, ashkoko, or Cape cavy, also consists of two pouches, separated by a middle partition, Compara. in which there is an aperture for mutual communication. . tive In the hippopotamus the cardia communicates with three ^ pouches, two of which only are cognizable without, and with a long tubular bowel, the interior of which is divided across by several valvular folds. In the kangaroo the stomach receives the oesophagus near its left extremity, which is small and bifid (Plate XXXV. fig. 8); and forming a larger cavity on the right, passes upwards, making a turn, and crosses to the left be¬ fore the oesophagus, makes another turn, and again crosses the mesial plane to the right, where it terminates in a ta¬ pering cavity at the pylorus. In this couise it presents internally a longitudinal band (l, l, l), extending all round to near the pyloric end, and crossed by valvular membra¬ nous folds, which divide the cavity into cells not unlike those of the colon, especially in the horse. The mucous epidermis is continued from the oesophagus over the space marked c, c. The stomach of the Ruminants consists of four distinct Quadriln- but communicating cavities. The first, denominated the cuiar sto- Paunch (xo/X/a, rumen, penula, ingluvies; la pause, Vherbier, ™ach of. la double), is a large bag occupying the left side of the abdomen chiefly, marked externally by two saccular appen¬ dages, and separated within into four parts. (Plate XXXV. fig. 1, a, A, a, a.) Its inner surface, upon which the epider¬ mis is continued, is occupied by flat papillce. By a pretty wide aperture (b, b), with rounded margins, this communicates with the second cavity named the Kings- hood {/ti'KP'o(pcLhog, reticulum, le bonnet), which is distinguish¬ ed by the rhomboidal and polygonal cells, into which its inner membrane is moulded. An aperture at the further end of this (c) leads into the third or smallest cavity, termed the Maniplies (iyjvQg, omasum, lefeuillet), from the numerous concentric crescentic folds formed by its inner membrane (fig* 2, c and p). These folds amount to about 40 in the sheep and 100 in the ox. The smallest of them, between the aperture from the second into the third ca¬ vity, are puckered or collected towards their further end by a transverse membranous fold, which acts as a valve to the aperture between this and the fourth cavity. This one, generally named the Red (rjvuffrgov, abomasum, la caillette), is of an elongated pyriform shape, slightly incurvated on itself (fig. 2, d), and is marked internally by longitudinal folds (p) incurvated according to the curvature of the ca¬ vity itself, and terminating near the pyloric end in rugce or irregular duplicatures (r). This is the structure of the gastric cavities in the ox. In the camel, dromedary, and lama, the stomach is equally complicated, though the structure is a little differ¬ ent. In the first of these animals, which may be taken as an example of the others, the Paunch or first cavity is a large bag, divided into two compartments on the pos¬ terior part, by a strong band passing from the right side of the cardiac orifice longitudinally downwards (l, l, fig. 3), and forming one border of a groove leading to the orifice of the second. From the left margin of this band pro¬ ceed eight muscular bands, nearly at right angles, and intersecting with others, form cellular cavities on the left side of the paunch (n) ; while on the right side there are similar cells, though smaller, and wholly uncon¬ nected with the longitudinal band. From the left mar¬ gin of the cardia, in like manner, proceeds a broad muscular band (m, fig. 3) to the aperture (b) of the Paunch into the Kingshood, after which it takes another direction (m, fig. 4) towards the Maniplies or third ca¬ vity, within the orifice of which it terminates (c, fig. 4) The Red or fourth chamber is much the same as that of the bullock (d, p, r, fig. 5), and the only peculiarity is, that after terminating in (n) the pylorus, it opens in a small cavity (o) which leads into the duodenum (A). * " ANATOMY. From this description, for the particulars of which we are indebted to the accurate account of Sir E. Home, it results that the stomach of the camel differs from that of Waiter- ^ie 0X ant* ot^er horned ruminants chiefly in the pos- ells of thesession of the quadrilateral cells in the second stomach i 4" I'l trro i a Vvw 4-1-.^. ^ 1 1 1 Compara¬ tive Anatomy- 109 iuadrilo- uiar sto- 'rop of inis. ;amel. Into these the water is conveyed by the animal when drinking, and in these it remains. By the action of the muscular band (m), the aperture between the Paunch and Kingshood is opened, and the water is directed into it so as to fill its cells. When these are filled the surplus runs off into those of the first stomach, where at least those on the left side of the long band may be regarded as part of the general cellular structure. These cells are represent¬ ed of a large size in fig. 5, in which they appear like ob¬ longs with rounded corners. They are always larger on the left side of the band, in the Paunch, than those in the second stomach. Both in the bullock and in the camel, and in all the Ruminants, the first and second stomachs only are covered by mucous epidermis. In the Cetaceous animals similar complication of the gastric cavities is observed. In the bottle-nose porpoise, Yt acea which may be tak(:n asan example, the oesophagus, which LTAC A’ is large and capacious, terminates in a spheroidal or ovoi- dal flask-like bag (fig. 6, a, a) with an aperture a little be¬ low the cardiac, consisting of rose-like annular folds, and leading into a second cavity. This, which corresponds to the ruminant kingshood, is nearly spherical in shape (fig. 7, b), and presents valvular folds more circular than in the ruminants, and intersected by others so as to give it the honeycomb appearance characteristic of this cavity. From this another aperture leads into the smallest cavity of the three (c, fig. 7) ; and thence into the fourth, which is long, cylindrical, and slightly incurvated. The third cavity is remarkable for presenting in its inner membrane numerous apertures of mucous glands. Birds are distinguished by possessing a stomach con¬ sisting of three cavities. The first is the crop, which may be regarded as a mere expansion of the oesophagus, and confined chiefly to land birds. It is filled not only with food, but with small stones; and its chief purpose seems, by mechanical comminution, to supply the place of the teeth in dividing the granular aliment, and bruising or killing the animals swallowed. It is found chiefly in the granivorous birds. It is wanting in the ostrich, in the piscivorous birds, and most of the Graliae. I he second is the glandular crop or subsidiary stomach (ventriculus succenturiatus, bulbus glandulosus), a mem- brano-glandular sac, which may be also regarded as an oesophageal dilatation. It is larger when the crop is want¬ ing ; and though, when conjoined with it, it is always very glandular, and may be therefore regarded as a chemical solvent of alimentary substances, it appears to supply the want of the crop, which is certainly chiefly a mechanical apparatus. rIhe glandular crop or subsidiary stomach is remarkable for the number and size of the glandular bodies contained between its mucous and muscular tunics. These glands, though variable in shape, are generally conical; and some consist of several glands conjoined in one com¬ mon peduncle (Plate XXXVI. fig. 3). All of them are hol¬ low, and secrete a fluid which is discharged by one or nioie minute apertures, and which is of essential importance m the solution of the food. In some instances, as in the mencan ostrich (fig. 2), they are few in number, and oc- cupy only a small part of the posterior wall of the oesophagus. ie gizzard or proper stomach of birds may be consi¬ dered as a horny mucous membrane, somewhat cartilagi¬ nous, continuous with that of the oesophagus, and covered V two strong thick muscles, the fibres of which converge to a point. (Plate XXXVI. fig. 1.) In the carnivorous and piscivoious <7e«era of birds, especially those in which the dandular izzard. crop is wanting, the gizzard loses its muscular character, Compara- and is converted into a membranous pouch. live I he stomach of Reptiles does not present those dila- Anatomy, tations observed in Birds; and when it changes its dia-^^ meter or capacity, it is only progressively and insensibly, Its general diameter, nevertheless, is proportionally larger than m the two classes already noticed. Most generally without cul desac, its shape is spheroidal, more or less ob¬ long; its membranous walls are thin and transparent- its muscular layer almost imperceptible; the cellular identified with the mucous tissue; the situation of the cardia indeter¬ minate ; and the pylorus, without valve, is distinguished by a simple tapering contraction of the gastric walls, and the appearance of the structure proper to the intestines. In this class of animals, further, digestion appears to be less regulated by fixed principles than in the other two. It is evidently not confined exclusively to the sto¬ mach. The oesophagus of the turtle is provided with numerous large, firm, pointed processes, which in all probability contribute to the mechanical division of the food, so much the more requisite as the Cheloniad Rep¬ tiles are toothless. Except in the crocodile, the Sau- rial Reptiles are destitute of large arch or proper car¬ diac cavity. In the Ophidial or Serpentine Reptiles the stomach has the figure merely of a dilated sac be¬ tween the oesophagus and intestines, and presents no cur¬ vature. It is probably in connection with this modifica¬ tion of structure that we find animals remain for days in the oesophagus of serpents; and this tube appears to be to a certain extent capable of digesting aliment as much as the stomach. The best mark of distinction in such circumstances is the cessation of epidermis. In no class of animals does the stomach vary more in Stomach shape, structure, and situation, than in Fishes; and per-of fishes, haps the general character of the alimentary canal in this class is most justly given by representing it as deviating from those attributes of regularity which we find in the higher classes. While in the Mammalia and Birds it is always distinguished by its spheroidal or pyriform enlarge¬ ment between two tapering extremities, and by being much more dilated than any other part of the alimentary canal, in the Reptile class it begins to part with this cha¬ racter ; and it loses it altogether in the Fishes. In most of the finny tribes it is often not more capacious than the oesophagus ; and it is distinguished from this tube only by the villous character of its internal membrane. In gene¬ ral, also, the situation of this pyriform dilated sac is trans¬ versely across the body in the Mammiferous class. In the feathered tribes this character also is slightly set aside, and partly from the alteration in shape, partly from that of position, the stomach occupies less of the trans¬ verse diameter than of the longitudinal extent of the body. Among the Reptiles this character, though still retained in the Cheloniad, and even in the Saurial, is gradually enfeebled in the Ophidial ; and in the Fishes it may be said to be entirely obliterated, since the organ occupies much more longitudinal extent than transverse width of the body. The first character of the alimentary tube of fishes is the width or capacity combined with shortness of the oeso¬ phagus. The latter character is manifestly associated with the absence of lungs and consequent want of chest; so that between the throat and abdominal cavity, the in¬ terval, which corresponds only to the space occupied by the heart, is extremely abridged. The oesophagus con¬ sists, as in the other classes, of a mucous membrane sur¬ rounded by a muscular tunic; but the mucous mem¬ brane is distinguished by the firmness and whiteness of its corion, which in some genera approaches to the consistence of horn or cartilage, and by the presence of conical pa- pillce, sometimes of great hardness, and which appear to ANATOMY. 110 Compara- act mechanically on the food. It is almost superfluous to tive notice the facility which the large capacity of this tube Anatomy, affords fishes for swallowing their prey. Most of them are voracious in the extreme ; and it is not uncommon to find the stomach and oesophagus crammed to the throat. The figure and position of the stomach of Fishes are so variable, that it is difficult to give a character of gene¬ ral application. Though in many genera, especially of the Jugulares, it consists of a cylindrical sac with a slight dilatation immediately below the cardia, in others it is oblong ovoidal, as the ray and shark tribe ; and in others, as the sole, dory, and flat fishes generally, it is orbicular. In the sturgeon it consists of a cylindrical tube incurvated twice on itself. In none is there more than one cul de sac, the depth of which varies as the part corresponding to the pylorus is more or less remote from the fundus. When the limits of the stomach are indistinct, the situation of the cardia is equally so. In the lamprey (petromyzon) and pen-fish (syngnathus pelagicus) the whole tube is ot a uniform size from the mouth to the anus; and much the same may be said of the carp genus. The genera in which it forms a distinct dilatation or cul de sac are chiefly the following; the eel (inurcena anguilla), conger {m. conger), the bullhead genus (cottus), the scorpeena hor- rida, labrus genus, perch, cuckoo gurnard, mackerel, her¬ ring, salmon, mormyrus genus, mullet, and silurus Bagre. In the anableps the dilatation disappears ; and in the chcetodon ciliaris and some others it is a large sac incur¬ vated in an arch-like bend. The intestinal canal in most of the Mammalia is very similar to that of man ; and the chief differences of differ¬ ent orders and genera are found in the difference of lon¬ gitudinal extent either of the whole intestinal tube or the comparative lengths of its several parts. Compara- From the time of Grew to that of Cuvier, and most five length mo(jern anatomists, it has been a point of some importance of the in- to determine the length of the intestinal tube in relation thebocf10 t0 t^iat t^ie body* comParative length, which is e °ty' greatest in the Mammalia, diminishes successively in the Birds, Reptiles, and Fishes. It has been occasionally stated by different anatomists, that the intestinal tube is longer, cceteris paribus, in granivorous than in carnivorous animals, and conversely. When we come, however, to com¬ pare the different lengths of this tube in the several tribes, we find that this statement demands modification. In the ape family its length varies from 5 to 8 times that of the body; in several of the lemur tribe from 4 to 6 times, the smaller length being in this case compensated by the size of the ccecum ; and in others of the lemur tribe, e. g. the lori, the intestine is only three times the length of the body. Among the Chiroptera there are two examples of very great contrast in this respect. While the intes¬ tine of the noctula or great bat (vespertilio noctula, Lin.) is the shortest of all the Mammalia, and scarcely does more than exceed the length of the animal’s body, that of the roussette (pteropus) or East India bat, which lives chiefly on vegetable matter, is at least 7 times longer than its body. A similar instance of the meeting of extremes is found in the Marsupial order, in which the marmoset and cayopollin have intestines only 21 times longer than the body, while that of the phalanger is more than 11 times longer. In the plantigrade or ursine family, which occasionally live on vegetable matters, the proportional length approaches to that of the ape. In the carnivorous animals the intestine, though gene¬ rally short, varies from 3 times to 8 times the length of the body. The former is the proportion in the lion, wild cat, ocelot, couguar, and weasel; and the latter in the hyena. Some of them also vary among themselves. Thus the intestine of the wild cat is greatly less than that of the domestic animal. The proportion is very great among the Rodentia, in several of which it is 8, 10,12, or 16 times Compara. longer, as in the agouti, than the body of the animal. Among tive the murine tribe, however, it undergoes a diminution, ^tomy. Among the Edentata, again, especially the sloth tribe, it diminishes very much, being only about 3-| times longer than the body in the Ai and Unau. This brevity is so much the more extraordinary that these animals are void of csecum, and live on vegetable matters; but, in all pro¬ bability, the duplicature of the gastric cavities in some degree compensates this deficiency. The intestinal tube attains its greatest proportional length in the Ruminant animals, being at least 11 times longer than the body, as in the goat, and 28 times longer in the ram. This immense length is supposed to compen¬ sate the absence of dilatation in the large intestines, and the small size of the caecum. In the Solidungula, again, which are remarkable for the large size of the caecum, the length of the intestine diminishes much, being 8 times longer than the body in the zebra, 9 times in the ass, and 10 times in the horse. Lastly, it is a singular circumstance, that in different species of the same genus the comparative length varies much. We have already noticed the difference between the length of the intestine in the wild and in the domestic cat. The wild and tame boar is a similar instance of the same, the intestine being only 9 times longer than the body in the former, and so much as 13^ times in the lat¬ ter. It is possible that such differences may depend on the different habits of the animal in his wild and domestic condition. This explanation, however, is totally inade¬ quate to account for the difference in the comparative length of the intestinal tube in the Asiatic and African elephant, being 10 times longer than the body in the former species, and only 7 times in the latter. The same may be observed of two animals very closely allied, if not of the same genus, the echidna and ornithorhyncus. The intestine of the former animal is 7 times longer than his body, while that of the latter is only 5 times. In Birds generally the intestine is shortest among those genera which prey on animals and fish; it varies from twice to five times the length of the body. In the galli¬ naceous and passerine birds, which live on grains, it is always longer and more capacious than in those which live on animal substances. In the cassowary, which is granivorous with a short intestine, the intestine is di¬ vided by contractions into distinct pouches, to compen¬ sate for the brevity of the tube. It must be remarked, nevertheless, that in several birds which prey on fishes, the intestinal tube is proportionally longer than in those which feed only on grain; and the proportional length is not diminished in birds living indiscriminately on ani¬ mal and vegetable aliment. The intestinal tube of the Reptiles is still shorter than that of Birds, and often it does not exceed twice the length of the body. It is longest in the Cheloniad, and shortest in the Ranine and Serpent tribe. In the tad¬ pole, however, a singular peculiarity is observed. The intestinal tube of the tadpole of a frog is nearly ten times longer than the space between the muzzle and the vent (anus); whereas, after the animal has become a frog, the intestine is only twice as long as this space. In the class of Fishes the intestinal tube is still shorter and more direct in its course to the vent or outlet. In a few which live chiefly on marine vegetables, for instance some of the chcetodon genus, it is about six times longer than the body of the animal; and in a few of the cnr\) genus (viz. cyprinus capceta) it amounts to ten or twelve times longer than the body. In others, however, of the same genus, for instance the cyprinus mursa, it is scarcely as long again, showing here once more an instance of the conjunction of extremes not easily explained. f ANATOMY. Compara- In most vertebrated animals the intestinal tube may be hve distinguished by natural marks into two divisions, one ex- Anatomy. tending between the pyloric end of the stomach to a part of the tube, where it becomes wider and more capacious; into ileum ^ie other from this to the vent or outlet. In some instances, Rnd calm, however, this distinction is very obscurely and imperfectly marked. In the Mammalia, in which the distinction is observed, it is indicated by one or more appendages, which, if large, are denominated cceca, and if slender and long, are termed vermiform processes. Man, the ourang, and the wombat (phascolomys), are the only animals which are possessed at once of ccecum and vermiform ap¬ pendage. In the other genera of the ape tribe, in the maki of the lemur, in the colugo among the Chiroptera, the ichneumon, many of the carnivorous tribe, the opossum and kangaroo, the Rodentia except the dormouse, the Cape ant-eater, the Pachydermata except the hyrax, the Ruminants, Solidungula, and Amphibia, there is only a caecum without vermiform process. The caecum is wanting in the sloths, the bat tribe, the Ursine except the ichneumon, the marten, pine-marten, weasel, &c. the dor¬ mouse, and all the Cetaceous animals. The presence of caecum or vermiform process, however, is not necessary to distinguish the canal into two portions. The inner or mucous surface of the ileum is always villous and uniform; and the whole intestine, except its supe¬ rior or pyloric portion, is convoluted in proportion to its length, and moves about freely in the abdominal cavity; whereas the colon is more or less fixed at different points, it is shorter and more capacious, and its inner membrane is merely mucous without long villi. A mark equally general is the semilunar duplicature of mucous membrane placed between the ileum and colon, and named the ileo¬ colic valve. In the sloth and armadillo tribes, which want caecum and vermiform process, this and the slight differ¬ ence of diameter are the only marks of distinction between the ileum and colon. In all the other Mammalia which are destitute of caecum the whole tube is of the same calibre, occasionally diminished towards the vent; and the division into ileum and colon is no longer cognizable. In all the Mammalia with one caecum, it appears in the form of a production from the large intestine beyond the part at which it receives the ileum; and though va¬ riable in its diameter and structure, it bears a general re¬ semblance to the colon in these respects. In herbivorous animals, and even in some that are omnivorous, as the ape and lemur tribes, it is generally large and puckered by tendinous bands. To this, however, an exception is ob¬ served in the Ruminants, in which the caecum is mode¬ rate in size and unpuckered. It is small and unpuckered in the kangaroo-rat and wombat; while, conversely, in the colugo and brown phalanger, which are believed to be chiefly zoophagous, it is very large and puckered. In the zoophagous animals generally both the colon and ccecum are of small calibre, little different from that of the ileum; and both the colon and cascum are destitute of cells or compartments. In herbivorous and several om¬ nivorous animals, on the contrary, the inner surface of the colon is divided by longitudinal and transverse bands into a number of cells or compartments. From this rule, how¬ ever, there is an exception in the wombat, kangaroo, and the Ruminants. In the Rodentia the colon is cellular at its commencement only. In birds the canal is provided with two cceca, one on each side, not far from the vent. In the omnivorous and g—us these cceca are generally long and capacious. Vy hue they are very large in the nocturnal predatory birds, they are either obliterated or wanting in the diur¬ nal predatory birds, in the green woodpecker, the lark, and the cormorant. In the heron, bustard, and grebe, there is a single small one; in the cassowary two very 111 andlhick3”*1 m ^ merSanser> diver, &c. they are short Compara- In all birds the short bowel between the insertion of the Anat°my- caca and the clocwa is a little wider and more capacious than those between the pylorus and the cceca ; and this is the only circumstance which indicates in this class the dis¬ tinction of the tube into ileum and colon. In the reptiles the intestinal tube is generally void of cceca or appendage; and the only distinction consists in the one part of the tube, which is long and slender, being joined to another which is short and thick, and in the presence of a semilunar membranous fold at the point of insertion. In the iguana alone has a genuine ccecum been observed.” The distinction into small and large intestine, or ileum and colon, is still less obviously observed in the class of fishes. It sometimes happens that the difference of capa¬ city is inverted, and that the calibre of the portion which terminates at the vent is actually smaller than that of the part connected with the stomach. This arrangement is observed in the ray, shark, sturgeon, and even the bichir; in the syngnathus, trunk-fish, and balista. In other in¬ stances the diameter is the same throughout; and the only distinction is derived from the anatomical characters of the inner membrane. In the lamprey, sea-devil, rough star-gazer, radiated sole, holocentrus sago, carp tribe, mor- myrus, and mullet, it is impossible to distinguish the intes¬ tine into large and small. Fishes resemble Reptiles in being destitute of Pyloric ap- at the junction of the small and large bowel. In many ofPendages them, however, there is attached to the intestine, some-ot fishes- where below the pylorus, a variable number of small intes¬ tines terminating in blind ends, similar in size and struc¬ ture to the intestine with which they communicate. These tubes, which have been not very happify named pyloric appendages {appendices pyloricce), in so far as they are most frequently connected rather with the part of the bowel corresponding to the duodenum, vary in number from 2, 4, 6, or 8, to 80 or 180 in some genera, and even their number is not the same in different species of the same genus. Thus, while there are 6 in the smelt {salmo eperlanus), there are 68 in the s. lacustris, and 70 in the salmon {s. salar). In like manner, though there are 18 in the anchovy {clupea encrasicolus), there are 24 in the herring {c. harengus), and fourscore in the shad (c. alosa). In some, as the cod and pollach, they consist of several large trunks ramified into numerous small ones. These appendages, however, are wanting in the carti- Peculiar laginous fishes with free branchice, in most of those with fo™ of the fixed branchice, in the Apodes, and in several of the tho-aPPen* racic and abdominal order. In the sturgeon and somedages* others they are represented by a series of communicating cavities inclosed in the intestinal membrane, which is covered by a cellulo-muscular tunic and peritoneum (Plate XXXVI. fig. 5), and which assumes the external appear¬ ance of a pancreas. Among the cartilaginous fishes the brevity and direct- The spiral ness of the intestinal tube is compensated by a peculiar dis- valve ot position of the intestinal mucous membrane. This consists ^ies* in part of the membrane projecting like a broad fold or pro¬ cess from the inner surface of the intestine, and winding round from the pyloric to the anal or lower extremity (fig. 7 and 8). This, which is denominated the spiral valve, may be easily understood from these figures, which repre¬ sent the arrangement as it is observed in the shark. In the sturgeon, in which it is found in the last portion of in¬ testine (fig. 6), its peculiarities have been described by the writer of this article in the Wernerian Transactions, vol. vi. In all the Mammalia the intestinal tube terminates/fectam. in a distinct bowel denominated the rectum, the mucous membrane of which is continuous with the skin at the ANATOMY. 112 Compara- anus. This rule can scarcely be said to be violated in tivc the case of the echidna and ornithorhyncus, in which there Anatomy. jg an aperture at the lower part for the urine and the semen of the male and the ova of the female. These anomalous and singular animals form a transition to the mode in which the intestinal tube terminates in the three genuine oviparous classes. In Birds, Reptiles, and most of the cartilaginous Fishes, the intestinal tube terminates in an outlet common to it with the urinary organs, denomi- Cloaca. nated generally the cloaca. In the sturgeon, however, it has been shown, in the paper already mentioned, that there is a distinct urinary outlet; and that consequently this ani¬ mal cannot be said to have a cloaca. In the greater part of fishes, while there is one vent for the excrement, there is another common one for the urine, the ova, and the spawn. On the subject of the liver, spleen, and pancreas, it is impossible to enter with any interest in this sketch. CHAP. II. SECT. I. THE HEMATROPHIC ORGANS. The Mammalia and Birds agree in having a heart con¬ sisting of two pairs of chambers, a venous auricle and ventricle, and an arterial auricle and ventricle. The Eustachian valve is often wanting in the Mammalia. It is wanting, for instance, in the lion, bear, and porcupine; while it is broad and muscular in the seal, and assumes a spiral direction along the upper walls of the right auricu¬ lar sinus in the elephant. It was at one time imagined that the aquatic Mamma¬ lia were distinguished from the terrestrial by the foramen ovale being open and forming a communication between the two auricles. This, however, is a mistake, at least in the adult animal; for neither in the otter, the seal, nor the porpoise or dolphin, did Cuvier find this aperture per¬ vious ; and it may be inferred, that when it is open, it is an anormal remain of the fetal structure. In the orni¬ thorhyncus, also, according to Sir Everard Home, it is im¬ pervious. In the porcupine and elephant, in which there are two anterior vence cavce, the blood of the left anterior cava, which opens in the sinus near the aurico-ventricular aperture, is conveyed directly into the right ventricle. The reptile heart, the first in the cold-blooded division, varies somewhat in the several tribes. In the first three, the Cheloniad, Saurial, and Ophidial, it consists of two auricles and one ventricle, divided in some instances into communicating chambers. In the Batrachoid family, on the contrary, it always consists of one auricle and one ventricle, the interior of which is unilocular or undivid¬ ed. In several of the Turtle tribe, among the first family, the ventricle consists of a pulmonary chamber, in which the blood is more particularly directed to the pulmonary artery, and a general or aortic chamber, which is above, and from which the blood is conveyed into the aorta. In the crocodile the ventricle is divided into three chambers, communicating by several apertures. One is inferior and to the right, and communicates with the right auricle by a large aperture provided with two valves. On the left, and before, is the second chamber, receiving the orifice of the left descending aorta. Behind is an aperture leading into the smallest chamber of the three, situate at the mid¬ dle of the base of the heart, and receiving the common trunk of the pulmonary arteries. The left chamber is above. In the Ophidial or Serpentine family the ven¬ tricle is divided into two chambers, a superior and infe¬ rior, separated by an imperfect partition, which allows the two to communicate. The heart of the finny tribes is as simple as that of the Ranine reptiles, which indeed constitutes the preparatory step in the descending scale of organic forms. It consists, as in these animals, of two chambers only, an auricle and ventricle- The former receives the blood from the body at large, and transmits it to the ventricle, which is almost Compara. in all cases unilocular. From this a single vessel conveys the it, not to the body at large, but to the gills, from which it is again collected by several branchial veins. Of the blood-vessels of the four vertebrated classes it is superfluous to speak in any detail. The most remarkable circumstances are the minute subdivisions which in some classes the arteries undergo previous to final distribution. In the Ruminants, and se¬ veral of the Pachydermata, the branches of the carotid artery, instead of uniting by the communicating vessels, are subdivided into a great number of minute vessels, which form round the pituitary gland a communicating plexus, denominated by the ancients Rete mirabile. In the slow lemur {lemur tardiyradus) Sir A. Carlisle found the subclavian artery, after entering the axilla, di¬ vide into 23 arterial cylinders of equal size, and the iliac on the brim of the pelvis into at least 20 equal-sized tubes, which in both cases surrounded the principal artery, redu¬ ced to a small vessel, and, proceeding along the extremity, were distributed chiefly to the muscles. {Phil. Trans. 1800.) A similar arrangement, carried to a still greater ex¬ tent, was found in the Ai or three-toed sloth, in which the axillary and iliac arteries were divided into about 60 or 65 cylindrical parallel tubes. In the slender lemur {Lemur laris') these vessels are subdivided into 4 or 5 only. In Fishes in which the unilocular ventricle sends its blood to the gills only, the heart is pulmonary, and the arterial system is destitute of central impulsive organ. In the sturgeon, which is one of the best examples of the distribution of the arterial system in the finny tribes, the blood, which is distributed in the branchial by the large artery, is collected in numerous vessels, which may be regarded as analogous to the pulmonary veins of the warm-blooded classes, but which have thick parietes like arteries; and these uniting, form a large vessel, which is lodged in a cartilaginous canal formed by the continuous bodies of the vertebra. This vessel is further void of com¬ pressive or elastic tunics, and the blood moves through it as through an immovable and inelastic tube. From its sides, however, a series of arterial vessels issue, which forthwith assume the usual characters of arterial tubes. In many other fishes the parietes of the large artery adhere in part to the semi-osseous canal in which it is lodged. SECT. II. THE ORGANS OF AERATING CIRCULATION. The lungs of the Mammalia are in all essential points perfectly similar to those of the human subject. The lungs of Birds differ chiefly in not presenting dis¬ tinct lobules, in having the air-vessels larger and more dis¬ tinct, in the branchial tubes not becoming quite so small, and in terminating not alone in the pulmonic vesicles, but in perforated parts of the surface of the lungs, which lead into large air-sacs, communicating with all parts of the body, and forming an accessory lung. In the ostrich, which may be taken as a general example, there are four of these cells or aerolabous sacs. The first, which is anterior, extends from the apex of the chest to the iliac bones, between the first ribs and heart above, and between the lower ribs and a cell which surrounds the intestines. It is divided into four chambers, the first two communicat¬ ing with the lungs by large apertures, while the fourth opens in the iliac bones. Behind this large sac are two small ones, between the iliac bones and the peritoneal sac. Before it is another small one occupying the lateral regions of the apex of the chest, and communicating with sacs in the axil¬ la and neck. Besides these, the stomach, liver, heart, and intestines are surrounded by sacs. All of these communi¬ cate by saccular processes with the cavities of the bones. By this peculiar arrangement Birds possess the greatest extent of respiratory surface of all classes of animals. ANATOMY. 113 Compara¬ tive Anatomy. The lungs of Reptiles are distinguished by consisting of the erectile movable tubular fangs. Fig. 15 is the head of Compare the innocuous, and 16 of the poisonous serpent. PART III. REPRODUCTIVE ORGANS. Undei this head we mention only the nipple-bag (rnarsu- Tempo- rarv gills of the tad¬ pole. Urinary organs of the ovi- parous classes. Poison gland and fangs of serpents. large sacs, subdivided by membranous partitions into poly¬ gonal cells, which again are subdivided by smaller slips into smaller cells. In these cells the bronchial tubes are not ramified, but divide abruptly in them at the sur¬ face of the lung. Some idea of this arrangement may be obtained from the lung of the ordinary land-tortoise pium mammillare), or secondary uterus of the Marsupial (Testudo Graca, Plate XXXVII. fig. 1). The sacs or animals (Plate XXXVII. fig. 7); the nipples (fig.8); and large cells are smaller and more numerous in the turtle the manner in which the foetal animal, in a verylmperfect (fig. 2); but the general disposition is much the same. and embryal form, becomes attached by the mouth to the The young of the Batrachoid family, and several of nipples (fig. 10). The il/arswjomm, therefore, ought to be re- the water-lizard tribe, are provided with fimbriated or garded, not as a mere pouch in which the young may take ciliated processes attached to the neck, and which are in refuge after they are grown, but as a subsidiary uterus, com¬ all respects similar to the gills of fishes. These gills dis- bining the character of the Mammae of the other orders, appear as the animal grows; and when it assumes the true The Mammalia are peculiar in possessing a uterus. In ranine or reptile character, vesicular lungs like those of the other classes this organ is withdrawn, and the ovary other reptiles, and which had continued in a hitherto (fig. 11) and oviduct alone are left. In the ovo-viviparous latent and rudimental state, are developed, and the ani- animals, as the ovo-viviparous shark, the oviduct (fig. 12) mal breathes as others of the same tribe. resembles that of the common fowl. In the lower classes A peculiar form of respiratory organ is found in the the ova are hatched out of the body entirely. tive Anatomy. lamprey or seven eyes, and the two species of hag-fish, (Myxine, Lin.; Gastrobranchus, Bl.; and Gastrobranchus Dombey). The former has on each side seven apertures leading into cylindrical tubes, in which the branchiae are contained. (Plate XXXVII. fig. 3.) In the two species of hag these tubes are dilated into ovoidal cavities, in In the space assigned to this article, it was impos¬ sible to treat fully of a subject so extensive as the struc¬ ture of the animal world; and while the author has ar¬ ranged its divisions in such a manner as to show in what order it may be most easily and advantageously studied, which the water is received, and on the membrane of he has introduced only those topics which are most indis- which the branchial vessels are distributed. In this re- pensable, and most require illustration. For more com- spect, therefore, the hag-fish approaches to the mode plete details, therefore, he refers the reader to the follow- of respiration among the cephalopodous Mollusca, in ing works. which the branchiae are inclosed in a cavity. Lastly, in 1. Lemons d'Anatomic Comparee de G. Cuvier, Membre the Aphrodite aculeata, which may be taken as an example de I’lnstitut National, &c.; recueillies et publiees sous of the respiration of worms, there is a series of tubes like ses yeux par C. Dumeril, chef des Travaux Anatomiques, tracheae and bronchi, proceeding from the surface to the interior, and in which the water containing the air requi¬ site for respiration is received. (Fig. 6.) SECT. III. SECRETORY ORGANS. Under this head ought to be described the urinary or¬ gans of the four vertebrated classes. Those of the Mam¬ malia agree in consisting of kidneys more or less lobu- lated, ureters or excretory tubes, a reservoir or urinary bladder, and a urethra opening on the same mucous sur¬ face with the organs of generation. In the three oviparous classes considerable changes are made. Though in Birds and Reptiles the glandular organs denominated kidneys are left in the shape of aggregated glands with the two excretory tubes, the bladder is withdrawn, and the ureters open in the cloaca. The only apparent exceptions are the ostrich and cassowary, in which the cloaca is so orga¬ nized that it may serve as a bladder or temporary recep¬ tacle of the urinary secretion. In the Reptiles the pre¬ sence of this organ is variable, being found in the Che- loniad and Batrachoid; and the iguana, tupinambis, chameleon, stellio, and dragon, among the Saurial tribe ; but wanting in the crocodile, lizard, agami, gecko, and the whole Ophidial tribe. In Fishes it is not less variable. While the ray and shark tribe are destitute of bladder, and the ureters terminate in a cloaca, this receptacle exists in the sea-devil, lump-fish, globe-fish, and others of the cartilaginous division. A peculiar secreting organ, deserving notice, is the poi¬ son gland of the poisonous serpents. It is a glandular body situate on each side above the upper jaw, behind and be¬ low the eyes, with a considerable cavity, which opens into &c. Cinq tomes. Paris, tome i. 1799;—tome v. 1805. 2. Blumenbach’s Manual of Comparative Anatomy ; with additional Notes by W'illiam Lawrence, Esq. F. R. S. Se¬ cond edition, revised and augmented by William Coulson Lond. 1827, 8vo. The notes are derived chiefly from the work of Cuvier and the papers of Sir E. Home in the Philosophical Transactions. 3. Gore’s Translation of Ca¬ ms's Introduction to the Comparative Anatomy of Animals. Lond. 1827, 2 vols. 8vo. The arrangement of this work, in which the author examines the forms of organs as they ascend, from the lowest to the highest classes, diminishes its general interest. 4. Lectures on Comparative Anato¬ my, in which are explained the Preparations in the Hunte¬ rian Museum. By Sir Everard Home, Bart. Lond. 1823, 6 vols. 4to. This work consists of the papers read by the author at the Royal Society, and published in their Transactions. Though entitled, therefore, Lectures on Comparative Anatomy, it embraces a much more exten¬ sive field, and contains a great number of physiological and pathological papers. This renders it at once rather desultory and prolix. It contains, nevertheless, a great number of facts illustrative of peculiarities of structure in the animal world; and it is particularly valuable by the number of engravings with which it is embellished. It can scarcely be said to possess any arrangement whatever. 5. Recherches sur les Ossemens Possiles, ou Von retablit les characteres de plusieurs anirnaux dont les Revolutions du Globe ont detruit les especes. Par M. le Bar. G. Cuvier, &c. Nouvelle edition. Tome i. 1822, Osteology of the Elephant, Hippopotamus; tome ii. partie i. 1822, Osteology of the Rhinoceros, Horse, Hog, Daman, and Tapir; tome iv. 1823, Osteology of the Deer and Ox, the Bear, Hyena, i. a long excretory tube, lying along the outer surface of the Lion, Glutton, Wolf, and Dog; tome v. partie i. 1823, upper jaw, and opening in the tubular tooth, represented Osteology of the Reptiles, the Ichthyosaurus and the at fig. 17 and 18; and which is movable in an articulation, Plesiosaurus; partie ii. 1823, Rodentia, Edentata, and may be erected, as in fig. 18, or depressed, as in 16, at Monotrema, Amphibia, and Cetacea. Paris, 1824. the will of the animal. The poisonous serpents are there- These papers contain much accurate osteological descrip- foie distinguished from the innocuous by the presence of tion. (d. C.) VOL. in. P 114 ANA Auatomy AnATOMT Act, AND ANATOMICAL SCHOOLS. Notwith- Act standing the reputation to which a few British anatomists II have attained within the last hundred years, before the pass- gorasT *ng ^'e Anatomy Acts of 1831 and 1832 the study of practical anatomy in Great Britain was all but proscribed by statute. Early, it is true, in the sixteenth century, by way of encouraging anatomical studies, it was ordained that “ the bodies of four murderers should be delivered after execution to the corporation of barber-surgeons of London, for the purposes of dissectionand at that time we were not much behind the rest of Europe in anatomical know¬ ledge : but our legislation regarding the supply of bodies for the dissecting-room remained stationary, while the rest of the world was advancing, as became apparent by the fact, that until the middle of the last century our students were forced to seek anatomical knowledge in the various schools of Italy or of Holland. Yet our courts of law were in the habit of punishing medical men for professional igno¬ rance, and our public boards of requiring anatomical skill in those who appeared before them for examination, while the laws prohibited the means of obtaining it at home ; and it was even penal for any one to be in possession of a human body for anatomical purposes, except it were that of an exe¬ cuted murderer. In defiance, however, of such strange discouragements, anatomy, especially in London and Edinburgh, made much progress, by the public winking at notorious transgressions of the law; but this anomalous state of things produced a class of offenders termed body-snatchers, whose revolting and, in some instances, atrociously criminal modes of sup¬ plying the dissecting-room were exposed in the parliamen¬ tary inquiry that preceded the Act now noticed. By previous Acts of Parliament the criminal courts had been empowered to annex to the capital sentence on a mur¬ derer, that his body should be publicly dissected. But it was justly considered that thus the idea of great crime was connected with dissection, and the prejudices of all classes against anatomy greatly increased. Accordingly, in the se¬ cond year of William IV., a parliamentary committee inves¬ tigated the subject, and in the following year an act was passed that abolishes dissection as a part of any criminal sentence, legalizes schools of anatomy, and permits the pos¬ session of human bodies for the purpose of dissection, under judicious regulations, which are sufficient to prevent the revolting practices of the body-snatcher, and the still more atrocious crimes for which Bishop in London and Burke at Edinburgh were executed. Under this act the supply of bodies in our anatomical schools has been sufficient, without violating the sepulchres of the dead, or outraging the feel¬ ings of the living. The average supply of bodies to the London schools is estimated at 600 annually.—See Report of House of Commons, of 22d April 1829 ; and Anatomy ^ay 1829> of 11 th December 1831, and of Sth jyiciy 1 oOi^. ANAXAGORAS, an eminent philosopher of antiquity, was born at Clazomenae (now Kelisman), in the first year of the 70th Olympiad, or 500 b.c. (Apollodorus). His family was rich and noble, but he early sacrificed the pro- spects of worldly ambition to his passion for philosophy Leaving his patrimony to be cultivated and enjoyed by his relations, he gave himself up to the contemplation of nature which he regarded as the true object of man’s existence! lo philosophy, he afterwards said, “I owe my worldly rum, and my soul’s prosperity.” Some writers call him the pupil of Anaximenes ; but this statement, if taken literally is irreconcileable with chronology. According to others, he enjoyed the instructions of his countryman Hermotimus who, according to Aristotle, was the first to proclaim the doctrine of a supreme regulative intelligence. At the age ANA of 20, or according to others, of more than 40, he went to Athens, at that time entering on the most brilliant period of its history, and there continued for 30 years. His philo-' sophical teachings soon drew around him the best intellects of Athens, and he numbered among his pupils Pericles Eu¬ ripides, Archelaus, and probably also Socrates. Without interfering in the public affairs of the state, he contented himself with forming the minds of its rising youth in the principles of wisdom. But neither the elevation and disin¬ terestedness of his character, nor the powerful friendship of Pericles, could ward off the shafts of persecution. The philosopher was accused, like Socrates in the next genera¬ tion, of impiety (ao-efieLa) and enmity to religion, in intro¬ ducing new and dangerous opinions concerning the gods. He was charged, among other things, with teaching that the moon was but a mass of matter like the earth, and the sun (the bright Apollo) a fiery mass of inanimate substance. The philosopher was tried and condemned to die; but the eloquence of Pericles procured the commutation of the sen¬ tence into a fine and banishment. Anaxagoras retired to Lampsacus, where he continued to teach philosophy till his death in the 73d year of his age, b.c. 428. “ It is not I ” said he in his exile, “ who have lost the Athenians, but the Athenians who have lost me.” The day of his death was for several centuries commemorated by a yearly holiday called the Anaxagoreia, in all the schools of Lampsacus. Opinions the most contradictory have been attributed to this philosopher. From the fragments that survive of his writings, and the statements of others regarding his opinions, it is impossible to obtain a systematic view of his doctrines. Diogenes Laertius, in his Life of Anaxagoras, has collected,' with little care and judgment, details which were scattered through various writings. It appears that, in the midst of some extravagant conceptions, Anaxagoras held opinions which indicate a considerable acquaintance with the laws of nature. His idea of the heavens seems to have been that they were a solid vault, originally composed of stones ele¬ vated from the earth by the violent motion of the ambient ether, inflamed by its heat, and by the circular motion of the heavens fixed in their respective places. He considered the sun to be a fiery mass of stone larger than the Pelo¬ ponnesus ;' and Xenophon introduces Socrates as refuting that doctrine, and delivering an unfavourable opinion con¬ cerning his other writings. The moon he believed to be inhabited, and to have its light reflected from the sun. Lienee we find his disciple, Euripides, calling the moon not the sister, but the daughter, of the sun. From his perceiv¬ ing that the rainbow is the effect of the reflection of the solar rays from a dark cloud, and that wind is produced by the rarefaction, and sound by the percussion of the air, le seems to have paid considerable attention to the pheno¬ mena of nature. Our information is more correct concerning his opinions of the principles of nature and the origin of things. He imagined that in nature there are as many kinds of principles as there are species of compound bodies ; and that the pecu¬ liar form of the primary particles of which any body is com¬ posed is the same with the quality of the compound bodyitself. L or instance, he supposed that a piece of gold is composed of small particles which are themselves gold, and a bone of a great number of small bones: thus, according to Anaxago¬ ras, o les o every kind are generated from similar particles. he universe, according to him, consisted in the beginning of an mfimte variety of these elementary principles (VouyA), which were afterwards mixed and arranged' by the moving force of intelligence (vovs). “ He was the first,” says Dio¬ genes Laertius, “who superadded mind to matter, open¬ ing his work in this pleasing and sublime languageAll m0s were con used; then came mind and disposed them ■Anaxa¬ goras. ANA inaxar- jn order.” Aristotle, in like manner, says, that he taught cyS that intelligence was “ the cause of the world, and of all \naxi- order 5 and that while all things else are compounded, this lander. alone is pure and unmixed ” Reason (Aoyos) he held to be -.S—* the regulative principle of the mind, as the nous is of the universe. The senses inform us regarding external pheno¬ mena ; but this information, he held, required the correction of reason. The fragments of Anaxagoras have been col¬ lected by Schaubach, Leipsic, 1827, and again in a better edition by Schorn, Bonn, 1829. ANAXARCHUS, a Grecian philosopher, who lived un¬ der Philip of Macedon and Alexander, was born in Abdera, and belonged to the sect generally known by the name of the Eleatic. said to have been instructed in his early studies by Diomenes of Smyrna, or Metrodorus of Chios. He had the honour to be a companion of Alexander; and a few anecdotes transmitted to posterity concerning him render it evident that he treated him with the usual free¬ dom of a friend. He checked the vain-glory of Alexander, when, elated with pride, he aspired to the honours of divi¬ nity) by pointing to his wounded finger, saying, “ See the blood of a mortal, not of a god.” We are likewise told, that, on another occasion, while the king was indulging im¬ moderately at a banquet, the philosopher repeated a verse from Euripides, reminding Alexander of his mortality. It is, however, to be regretted, that the fidelity of the philo- pher was wanting at the time when the mind of Alexander was tortured with remorse at having slain his friend Clitus ; for it is reported that on that occasion he endeavoured to soothe the agitated mind of Alexander by saying, that “ kings, like the gods, could do no wrong.” It is said that Nicocreon, tyrant of Cyprus, commanded him to be pounded in a mortar, and that he endured this torture with incredible patience ; but as the same fact is reported of Zeno the El¬ eatic, there is reason to suppose that it is fabulous; and it may be added, that this narrative is inconsistent with the general character of Anaxarchus, who, on account of his easy and peaceable life, received the appellation of “ The Fortunate. . Regarding his philosophical doctrines we have no information, save that he held the sovereign good to con¬ sist in perfect tranquillity of mind (ctara^eia). AN A XIL A U S of Larissa, a physician and Pythagorean philosopher, was banished from Rome by Augustus, b.c. 28, on the charge of practising the magic art. This accusation appears to have originated in his superior skill in natural philosophy,or what may be called “natural magic.”—Euseb. Chron. ad Olymp. clxxxviii; St Iren. i. 13; Plin. xix. 4 xxv. 95, xxviii. 49, xxxii. 52, xxxv. 50. ANAXIMANDER, a famous Greek philosopher, a friend or pupil of Thales, was born at Miletus in the 42d Olym¬ piad, in the time of Polycrates, tyrant of Samos, 610 b.c., and died at the age of 63. He was the first who publicly taught philosophy, or wrote upon philosophical subjects, and carried his researches very far into nature. It is said that he dis¬ covered the obliquity of the zodiac, was the first who pub- hshed a geographical table, invented the gnomon, and set up the first sun-dial in an open place at Lacedaemon. The pri¬ mary essence he held to be infinite (aVetpov), all-embracing, and divine ; that this infinite always preserved its unity, but that its parts underwent changes ; that all things came from it; and that all returned into it. According to all appearance, ne meant by this obscure and indeterminate principle the chaos °f the other philosphers. He asserted that there is « 111 ai Y °f worlds; that the stars are composed of air and ie, which are carried in their spheres, and that these spheres e gods ; and that the earth is placed in the midst of the universe, as m a common centre. He added, that infinite n SjV'Tr, 4,762,749 8,214,369 10,697,539 11,598,837 35,273,494 18,774,206 11,786,657 2,970,457 20,732,279 54,263,599 89,537,093 Maritime Statistics of Andalucia, including the Canaries, as to Foreign Trade, of which Cadiz is the centre, divided between the Provinces and Departments of—• Cadiz Motril San Lucar Algeciras., Almeria... Huelva.... Malaga Sevilla and Canaries.... Pilots. 618 Officials. 237 Cap¬ tains. 1291 Super¬ annu¬ ated. 35 Mariners. Able- bodied. 3318 Ordin¬ ary. 1714 Stran¬ gers em¬ ployed 4499 Carpenters. Skilful. 2135 Ordin¬ ary. 373 ANDAMAN Islands. These islands, which are situ¬ ated on the eastern side of the Bay of Bengal, are a con¬ tinuation of the archipelago which extends from Cape Ne- grais to Atchein Head, stretching from Lat. 10. 32. to 13. 40. N., and from Long. 90. 6. to 92. 59. E. They are called the Great and the Little Andaman. The Great Andaman, which is the northernmost, is 140 miles in length, and only 20 in breadth. It was formerly supposed to be one island; but two straits have been discovered, which open a clear pass¬ age into the Bay of Bengal, and divide the Great Andaman into three islands. The Little Andaman, which lies 30 miles south of the Great Andaman, is 28 miles long and 17 broad. It does not afford any good harbour, though tolerably safe anchorage may be found near its shores. These islands have an extremely moist temperature. They are situated in the direct current of the south-west monsoon 5 and the central mountains, some of the lofty peaks of which, as Saddle Peak in the Large Andaman, rise to the height of 2400 feet, in¬ tercept the clouds, which, for about eight months in the year, pour down incessant torrents of rain on the plains be¬ low. According to a meteorological table kept by an officer resident on the island, 98 inches of water appear to have fallen in the course of seven months. On the whole, how¬ ever, the temperature is milder than in Bengal, and the heat not so intolerable. The island is totally uncultivated, and the savage inhabi¬ tants glean a miserable subsistence from the spontaneous produce of the woods, in which the researches of the Euro¬ peans have hitherto found little that is either palatable or nutritious. The principal trees are the banyan-tree, the almond-tree, the oil-tree, which grows to a great height and yields a very useful oil; the poon, the dammer, the red wood, which for furniture is little inferior to fine mahogany; the ebony, the cotton-tree, the soondry, chingry, and beady; the Alexandrian laurel, the poplar, a tree resembling satin- wood, bamboos, cutch, the melon, aloes; the iron-tree of stupendous size, whose timber almost bids defiance to the axe of the wood-cutter. There are many other trees well adapted for the construction of ships; and, as in all the equatorial forests, there are numberless creepers and ratans, which surround the stems of the trees, and are so firmly interlaced together, that the forests are impervious, except a road be previously cut through them. The only quadrupeds seen on the island are hogs, rats, and the ichneumon ; also the iguana of the lizard tribe ; all which are very destructive to poultry. There are several species of snakes and scorpions, by which the labourers employed by the British in clearing away the underwood were frequently stung; but in no instance did. the sting prove mortal. The patient was frequently affected with violent convulsions, which gradually yielded to the operation of opium and eau-deTuce. Fish abound on the shores, and are caught in great num¬ bers during the prevalence of the north-east monsoon, when the weather is mild: gray mullet, rock cod, skate, and soles, are among the best. There are, besides, various other species, such as guanas, sardinas, roe-balls, sable, shad, prawns, shrimps, cray-fish, a species of whale, and sharks of an enor¬ mous size. Shell-fish are in great plenty, and oysters of an excellent quality. The shores abound in a variety of beautiful i Andelys. AND Andante shells, such as gorgonias,madreporas, murex, and cowries, with 11 many other sorts equally beautiful. Birds are not numerous, and they are extremely shy. Doves, ' parroquets, and the Indian crow, are the most common. Hawks from the neighbouring continent are sometimes seen hovering over the tops of trees; and a few aquatic birds, such as the king-fisher, a sort of curlew, and the small sea-gull, frequent the shores. Within the caverns and recesses of the rocks are found the edible birds’ nests so highly prized among the Chi¬ nese, and now occasionally brought into Britain. The whole population of the islands does not exceed 2000 or 2500, and they are probably the most uncivilised people on the face of the globe. They are far below the ordinary scale of barbarism ; and in their modes of subsistence, and in their dwellings, they rise very little above the brute creation. They wear no clothes, and seem insensible to any feeling of shame from the exposure of their persons. The woods supply them with little in the way of food. They are provided with no pot or vessel that can bear the action of fire, and they cannot there¬ fore derive much advantage from such esculent herbs as the forests may contain. The cocoa-nut, which thrives so well in the neighbouring islands, is not found in the Andamans, though the natives are extremely fond of it. The fruit of the man¬ grove is principally used by them. Their principal food con¬ sists of fish, in quest of a precarious meal of which they climb over the rocks, or rove along the margin of the sea, often with¬ out success during the tempestuous season ; but they eagerly seize on whatever else presents itself, such as lizards, iguanas, rats, and snakes. Their diseased and extenuated figures suffi¬ ciently testify that they have no abundant or wholesome nourish¬ ment. In stature the inhabitants of the Great Andaman seldom exceed five feet; their limbs are disproportionably slender, their bellies protuberant, their shoulders high, and heads large; and, what is singular and unaccountable, they have all the cha¬ racteristic marks of a degenerate race of negroes, with woolly hair, flat noses, and thick lips ; their eyes are small and red, their skin of a deep sooty black, while their countenances ex¬ hibit a mixed expression of famine and ferocity. Lieutenant Alexander describes the inhabitants of Little Andaman as far from being a puny race. When he landed in a boat he counted sixteen strong and able-bodied men, many of them very vigorous. The ingenuity of these savages is principally seen in the fabri¬ cation of a few simple weapons on which they depend for their subsistence. These are a bow from four to five feet long, with arrows of reed, headed with fish bone or wood hardened in the fire, a spear of heavy wood sharply pointed, and a shield made of bark.. With these implements they shoot and spear the fish, which abound in their bays and creeks, with surprising dexterity. I he settlement of these islands, with their negro in¬ habitants, so widely different in their appearance not only from all those of the Asiatic continent, in which the Andamans are embayed, but also from the natives of the Nicobar islands, pre¬ sents a curious problem, which has never been satisfactorily explained. It is supposed, however, by Symes, that the ori¬ ginal stock must have been settled on the island by the acci¬ dental shipwreck of some Arab slave-ship. The English made a settlement on the larger Andaman in the year 1793. Their object was to procure a commodious harbour on the east side of the Bay of Bengal, to receive and shelter ships of war during the continuance of the north-east monsoon ; also to provide a place of reception for convicts sentenced to transportation from Bengal. But the settlement, proving unhealthy, was aban¬ doned in 1796.. These islands, together with the Nicobar and other smaller islands, were included by Ptolemy in the general appellation of Insulce Bonce Fortunes, and were supposed by him to be inhabited by a race of anthropophagi, though there are no proofs of the modern inhabitants being addicted to can¬ nibalism. (Symes’ Embassy to Ava; Alexander’s Travels from, India to England, comprehending a Visit to the Burman Empire, dec.; Hamilton’s Gazetteer.) (d.b-n.) AND 125 ANDANTE, in Music, signifies a movement moderately slow, between largo and allegro. ANDEGAVI, a Gallic tribe, whose chief town was Ju- iiomagus, now Angers. AN DELI S, Les, an arrondissement in the department of 250 840 arrpr / i e*tends over 392 square miles, or Andena dfvidpd ? M mded lnto six cantons, which are sub- II t 1mtCOn-TneS’ and in 1851 contained 64,717 Anderson- inSSnf; I * t6f t0T’ °f thG Same name> had 5°69 RadwaT Th!, 18 fT mi 68 fr°m the Paris and Rouen nets, &c. manUfkCtUreS are fine cloths> cotton> bon- ANDENA in Old Writings, denotes the swath made in the mowing of hay, or as much ground as a man could stride over at once. ANDENNE, a town of Belgium, capital of a canton of the same name, arrondissement and province of Namur on the right bank of the Meuse, ten miles east of Namur. It is famous for its manufactures of porcelain and tobacco-pipe* In the neighbourhood are beds of pipe-clay, quarries of mar¬ ble, and mines of iron and lead. Pop. in 1850. 5316 ANDERAVIA. See Inderabia. ANDERNACH (the ancient Antunacum), a town in the Prussian province of the Lower Rhine and district of Coblenz, ten miles north-west of that town. It is situated on the Rhine, and was once strongly fortified, but its walls are now in ruins. It has tin and leather works; and ex¬ ports mill-stones and pounded tufa, used as a cement, which hardens under water, and is much used by the Dutch in constructing their dikes. Pop. in 1849, 3785. Lone. 7. 4 E Lat. 50. 57. N. 8 ANDERSON, Adam, was born in Scotland in 1692. He was a clerk for forty years in the South Sea House in Lon¬ don, where he published a large work entitled Historical and Chronological Deduction of the Origin of Commerce, containing a History of the Great Commercial Interests of the British Empire, &c., which is voluminous and heavy; but he seems to have anticipated in some of his speculations the opinions of later times. It was first published in 1762, in two vols. fol. A third edition appeared in 1797-9, in four vols. 4to, the last volume being an appendix and continu¬ ation by the editor, Mr Walton. Anderson died in 1765. Anderson, Alexander, a very eminent mathematician, who flourished in the early part of the seventeenth century. He was born at Aberdeen, but passed over to the Continent, and settled as a private teacher or professor of mathematics at Paris, where he published or edited, between the years 1612 and 1619, various geometrical and algebraical tracts, which are conspicuous for their ingenuity and elegance. It is doubtful whether he was ever acquainted with the famous Vieta, master of requests at Paris, who died in 1603; but his. pure taste and skill in mathematical investigation had pointed him out to the executors as the person most proper for revising and publishing the valuable manuscripts of that illustrious man, who had found leisure, in the intervals of a laborious profession, to cultivate and extend the ancient geometry, and, by adopting a system of general symbols, to lay the foundation and begin the superstructure of algebrai¬ cal science. Anderson did not come forward, however, as a mere editor; he enriched the texts with learned comments, and gave neat demonstrations of those propositions which had been left imperfect. He afterwards produced a speci¬ men of the application of geometrical analysis, which is dis¬ tinguished by its clearness and classic elegance. Of the time of this able geometer’s birth and death wre are ignorant. His brother David Anderson, a small pro¬ prietor in Aberdeenshire, but engaged in business, had likewise a strong turn for mathematics and mechanics, wdiich, joined to great versatility of talent, made him be regarded ^ by his neighbours at that period as a sort of oracle. The daughter of this clever and active burgess was married to John Gregory, minister of Drumoak, in that county, father to the celebrated James Gregory, inventor of the reflecting telescope ; and is supposed to have com- ANDERSON. 126 Anderson, municated to her children that taste for mathematical learn- ing which afterwards shone forth so remarkably in the family of the Gregorys. The works of Anderson amount to six thin 4to volumes, which are now very scarce. (j. l.) Anderson, Sir Edmund, a younger son of an ancient Scottish family settled in Lincolnshire. He was some time a student of Lincoln College, Oxford, and removed from thence to the Inner Temple, where he applied himself dili¬ gently to the study of the law, and became a barrister. In 1582 he was made lord chief-justice of the common pleas, and in the year following was knighted. He held his office to the end of his life in 1605. His works are, 1. Reports of many principal Cases argued and adjudged in the time of Queen Elizabeth in the Common Bench, Lond. 1644, fol.; 2. Resolutions and Judgments on the cases and matter agi¬ tated in all courts of Westminster in the latter end of the reign of Queen Elizabeth, Lond. 1655, 4to. Anderson, James, LL.D., was born at the village of Hermiston, in the county of Edinburgh, in the year 1739. His parents were in humble life, and had possessed a farm for some generations, which he was destined to inherit and to cultivate. At an early age he lost his parents: his educa¬ tion, however, was uninterrupted ; and conceiving that an acquaintance with chemistry would promote his professional success, he attended a course of lectures on that science, then delivered by Dr Cullen. Enlarging the sphere of his employments, Anderson for¬ sook his first possession, and rented in Aberdeenshire a farm of 1300 acres, which was then nearly in a state of nature. But previous to this he became known to men of letters, by some essays on planting, which, under the signature “ Agri¬ cola,” he ventured to commit to the world through the me¬ dium of the Edinburgh Weekly Magazine, in 1771. After withdrawing from his northern farm, where he re¬ sided above 20 years, he settled in the vicinity of Edinburgh. His agricultural speculations were still continued; and when a parliamentary grant was about to be proposed to Mr Elk- ington for a particular mode of draining land, he reclaimed the discovery as having been made by himself many years anterior. In 1791 Dr Anderson projected a periodical pub¬ lication called The Bee, consisting of miscellaneous original matter, which attained the extent of 18 volumes in octavo. It was published weekly, and a large proportion of it came from his own pen. From this period till 1803 he gave to the world a number of publications chiefly on agricultural subjects, which had no small influence in advancing national improvements. He has the great merit of being the first w'ho satisfactorily unfolded the true theory of rent. He showed by an original and able analysis that rent is not the recompense of the work of nature, nor a consequence of land being made private property, but that it depends on the various degrees of fertility of land, and on the circumstance of its being impossible to apply capital indefinitely to any quality of land, without receiving from it a diminished re¬ turn. Dr Anderson remained in his retreat, enjoying the culti¬ vation of his garden ; and after a gradual decline, partly occasioned by the over-exertion of the mental energies, he died in the year 1808, aged 69. He was twice married; first, to Miss Seton of Mounie; secondly, to an English lady. By his first marriage he had thirteen children, six of whom survived him. During a period of overstrained political fer¬ vour, certain papers formed part of the periodical works al¬ ready referred to, which were thought to contain a libel on the government. Although Dr Anderson’s principles were noted for attachment to the existing administration, he was called upon to give up the author of the obnoxious compositions, which he steadily refused, and, even in the face of the civil magistrates, charged his printers not to violate their fidelity Anderson to him and the author in betraying his name. The business terminated here, until a factious individual insinuated to the same magistrates that the compositions had proceeded from one of the supreme judges, whose party politics were avowedly hostile to those of government. Dr Anderson having learned the reproach, hastened to relieve the object of it by divulg¬ ing the name of the real author, who, to the universal sur¬ prise of the public, proved to be none other than the traducer himself. Anderson, James, W.S. This learned and indefatigable antiquary was the son of the Rev. Patrick Anderson, one of the many victims whom the tyranny of the government of his country condemned in 1678 to imprisonment on the Bass Rock, for attending a conventicle. This son was born at Edinburgh in August 5. 1662, and was educated to the legal profession, in which he became Writer to the Royal Signet, a station in Scotland which may be considered as equivalent to an Attorney and Notary Public. His character and acquirements stood so high, that just before the Union the Scottish parliament entrusted him with preparing for publication what remained of the public muniments of the kingdom; and in their last session sup¬ plied him with L.1940 sterling for defraying the expenses of that great undertaking. At this work he laboured for many years with great judgment and perseverance; but it was not completed at his death in 1728. The work was published under the care of the celebrated Ruddiman ; who in an excellent preface laments the death of his learned countryman, and adds, “tantumque non ad umbilicum pro- duxerat 6 -irdvv Jacobus Anderson.” This work is the great “Diploma'!’a et Numismata Scotia-:,” “ a publication,” says the sagacious but often too caustic Pinkerton, in his En¬ quiry, “ never to be excelled in elegance, and scarcely in exactness.” The labour of preparing this great national work had impaired his health and his fortune, notwithstanding the parliamentary aid; and soon after his death, the numerous plates, engraved by Sturt, were sold for L.530; but these plates are now lost, and the book has become exceedingly scarce. After the union of the crowns, Anderson was ap¬ pointed in 1715 Postmaster-General for Scotland, as some compensation for his valuable labours; but in the political struggles of 1717 he was ungraciously deprived of this office; and never again obtained any reward for his important ser¬ vices to his country. (T. s# Anderson, John, professor of natural philosophy in the University of Glasgow, was born in the parish of Roseneath in Dumbartonshire in 1728. He finished his education in that University, where he first became professor of oriental languages in 1756, but in 1760 was appointed to the chair of natural philosophy, a subject more suited to his tastes and acquirements. In this department he laboured assi¬ duously to apply scientific knowledge to the improvement of the mechanical arts. For this purpose he studied their processes in the various workshops of the city, and thus acquired an intimate acquaintance with those operations, which fitted him in an eminent degreee for the great object which seems to have been his chief aim, the scientific in¬ struction of the operative mechanic. He is, in fact, to be considered the father of those Mechanics’ Institutions which have since been so widely disseminated in this and other countries. He soon began to open classes for their instruction in the principles of their arts, in which his fami¬ liar extempore discourses were illustrated by appropriate experiments. 4 he working mechanic received every en¬ couragement from this eminent man to attend his courses, at which they were received in their working dresses. His anxiety for the improvement of the humble mechanic was not confined to his personal exertions. Shortly before AND Anderson, his death in 1796, he bequeathed the whole of his property to 81 trustees, for the purpose of founding an institution for educational purposes in Glasgow. He had seemingly in¬ tended it as a sort of rival to the university in which he was himself a professor; for his will mentions the founding of four halls or colleges with nine professors in each, for the faculties of arts, medicine, law, and theology! But the trustees found the funds entrusted to them utterly inadequate to so gigantic a scheme; and they contented themselves with founding what is now called the Andersonian Institution, or sometimes less correctly University. It was opened in 1797, by the appointment of Dr Thomas Garnett as professor of natural philosophy, who commenced with a popular course of lectures, which was attended by a considerable audience of both sexes. In 1798 a professor of mathematics and geography was appointed; and the in¬ stitution has since had the aid of several able teachers. In 1799 Dr Garnett was succeeded by Dr Birkbeck, who had the merit of introducing in the institution a system of scientific instruction annually to 500 operative mechanics, free of all expense to the pupils. On the removal of this excellent man to the London Royal Institution, he was succeeded by Dr Andrew Ure in 1804 ; and Dr Ure by Dr William Gregory. This institution still flourishes; and has been of vast benefit to the humbler classes of the citizens of Glasgow, (t. s. t.) Anderson, the fourth son of William Anderson, and of Margaret Melrose his wife, was born at Carnwath, in Lanarkshire, on the 7th of January 1750. His father was afeuar, that is, a person who possessed some small parcels of real property by the tenure of a perpetual lease. His first destination was for the church: in the year 1767 he was sent to the university of Edinburgh, and in due time was enrolled among the students of divinity. His school¬ fellow, James Graeme, who had entered the university at the same time, and with the same views, died of consump¬ tion in 1772, in the 23d year of his age ; and, after a short interval, his faithful friend published a collection of Poems on several occasions, by James Greeme. Edinb. 1773, 12mo. About this period he relinquished the study of di¬ vinity, and betook himself to the study of medicine. He was for a short time employed as surgeon to the dispensary at Bamborough Castle in Northumberland; and in a neigh¬ bouring town he then formed connections which had no small influence on his future destiny. On the 25th of Sep¬ tember 1777, he married Anne, the daughter of John Gray, Esq. of Alnwick, who was related to the noble family of that name. Returning to Scotland he took the degree of M.D. at St Andrews on the 20th of May 1778, after hav¬ ing been duly examined by the professor of physic. He now began to practise as a physician at Alnwick; but his general habits were rather those of speculation than exer¬ tion, and a moderate provision, acquired by his marriage, had emancipated him from the necessity of professional la¬ bour. In 1784 he finally returned to Edinburgh, w here he continued to reside for the period of 46 years, in a condition of life removed from affluence, but perfectly compatible with genuine independence and comfort. His amiable and affec- tionate wife died of consumption on the 25th of December 1785, in the 39th year of her age. In 1793, after having remained a widower for eight years, he married Margaret, the daughter of Mr David Dali, master of Tester school in the county of Haddington. For several years his attention was occupied with his edi¬ tion of The Works of the British Poets, with Prefaces Bio¬ graphical and Critical, which was published at Edinburgh, and extends to 14 large octavo volumes. The earliest vo- u™e’ which is now the second in the series, was printed in i92-3 ; the 13th was printed in 1795, and another volume was added in 1807. He was frequently solicited to revise AND hn, •he P°ntS’ ^ Publish *em in a separate form, t after having collected some materials for such a work, published deSign; In the mean time he had pubhshed T/ie JForfe of Tobias Smollett, « t of his Life and Writings. Edinb. 1796, 6 vols. 8vo. But the most able and elaborate of his p’oductionsisthetlurd edition of his Life of Samuel Johnson, tqi'/T O Wlth !,fltlcal Observations on his Works. Edinb i P6 SaT6 Service Which he rendered to Dr Smollett he afterwards extended to Dr Moore, having pub- hshed 7%e Works of John Moore, M.D., ivith Memoirs of his Life and Writings. Edinb. 1820, 7 vols. 8vo. At an earlier period he had published The Poetical Works of Ro¬ bert Blair ; containing the Grave, and a Poem to the Me¬ mory of Mr Law: to which is prefixed the Life of the Au- „ London’ 1794> 8vo- And his latest publication was 1 he Grave and other Poems, by Robert Blair ; to which are prefixed some Account of his Life, and Observations on his Writings. Edinb. 1826, 12mo. Dr Anderson contributed his ready aid to many different publications, and was always influenced, not by the love of money but by the love of literature. With many eminent men in England, Ireland, and America, he maintained a lite¬ rary correspondence ; and having survived most of his let¬ tered contemporaries, he enjoyed the esteem and considera¬ tion of a second and even of a third generation. No part of his character was more conspicuous than his uniform and un¬ abating zeal to promote the success of young men who disco¬ vered any promise, however moderate, of literary talent; and some of the more distinguished writers of our own age and nation \vere not without their obligations to his disinterested friendship. Mr Campbell dedicated to him his earliest and most popular publication, The Pleasures of Hope. Thomas Brown, John Leyden, and Alexander Murray, who all died at too early an age, were among the most eminent of his young friends. For Dr Brown, who became professor of moral philosophy in the university of Edinburgh, he enter¬ tained a very cordial esteem, which suffered no abatement or interruption. Another prominent feature of his mind was his ardent regard for the civil and religious liberties of mankind. This characteristic he displayed from the first years of manhood till the last day of his earthly existence. His bodily frame had never been robust; but the uni¬ form temperance and regularity of his habits contributed to prolong a life which was marked by cheerfulness and bene¬ volence. His faculties, mental and corporeal, betrayed few or no symptoms of old age. During the greater part of his last winter he was confined to his own house by what was considered as a common cold, and was attended by his friend and contemporary Dr Hamilton. Of the immediate prospect of death, he spoke, not merely with resignation, but even with cheerfulness; with the subdued but confi¬ dent hope of one who had long and habitually reposed on the assurances of the Christian faith. He died on Saturday, the 20th of February 1830, after having completed the 80th year of his age; and, according to his own directions, his remains were interred in Carnwath churchyard. His eldest daughter, Anne Margaret, was married in 1810 to David Irving, LL.D., and died in 1812, leaving an only His second daughter, Margaret Susannah, lived to 127 Andes. deplore the loss of a parent whose declining years she had soothed by the most exemplary attention to all his wants and wishes. (d. i.) ANDES. The Andes form a mighty mountain chain running nearly parallel to the western coast of South Ame¬ rica. The central ridge extends in an undivided chain from the Rio Atrato, at the Isthmus of Darien, in Lat. 8. N., to the Cordilleras of Vilcanoto and Cuzco, in Lat. 15. 50. S., where it separates into western and eastern ridges, that in- 128 ANDES. Andes, close the extensive and elevated valley of Desaguedero, and —^ exhibit some stupendous peaks that almost rival the altitude of the Himalayas of the East. After running parallel to each other to Lat. 19. 30. S., they again coalesce, and con¬ stitute one central chain to the Straits of Magellan, in Lat. 53. The Andes of South America then have a range of about 4200 miles. The most western of the two longitu¬ dinal ridges runs parallel to the Pacific, and is called the Cordillera of the Coast; the eastern chain is generally termed the Cordillera of the Interior, and its northern pro¬ longation Cordillera Real. The valley of Desaguedero extends from Lat. 15. 5. to Lat. 19. 30. S., with a varying breadth from 35 to 60 miles, presenting an area of 16,000 square geographical miles. It contains the celebrated Lake of Titicaca, the cradle of Peruvian civilisation. It was on the shores of this lake that Manco Capac, the first Inca, was miraculously discovered by the Quichu, the ancestors of the Peruvians. The Andes send out, nearly at right angles from their co¬ lossal ridge, between the latitudes of 14° and 20° south, three dependent branches, called by the Spaniards also Cordilleras. Of these secondary chains, the first and most northern is that of the coast of Venezuela, which is likewise the highest and narrowest. With an irregular altitude, it bends east¬ wards from the Atrato, forming the Sierra of Abibe, the mountains of Cauca, and the high savannahs of Folu, till it reaches the stream of Magdalena, in the province of St Mar¬ tha. It contracts as it approaches the Caribbean Sea, at Cape Vela; and thence extends to the mountain of Paria, or rather the Galley Point, in the island of Trinidad, where it terminates. This secondary chain attains its greatest known elevation where it rears the snowy summit, or Sierra Nevada, of St Martha and of Merida, the former being nearly 14,000 and the latter above 15,000 feet in altitude. These insulated mountains, covered so near the equator with eternal snow, yet discharging boiling sulphurous water from their sides, are higher than the Peak of Teneriffe, and can be compared only with Mont Blanc. In their descent they leave the Paramo or lofty desert of Rosa and of Mu- cachi; and on the west side of the Lake Maracaibo they form long and very narrow vales, running from south to north, and covered with forests. At Cape Vela the moun¬ tain chain divides into two parallel ridges, which form three confined valleys ranging from east to west, and having all the appearance of being the beds of ancient lakes. These ridges, of which the northern is the continuation of the Sierra Nevada of St Martha, and the southern the extension of the snowy summits of Merida, are united again by two arms which seem to have been placed by the hand of nature as dikes to confine the primeval collections of water. The three valleys thus inclosed are remarkable for their eleva¬ tion above the sea, rising like steps one above another the eastmost, or that of the Caraccas, being the highest. This plain was found by Humboldt to be elevated 2660 feet while the basin of Aragua was only 1350 feet in height’ and the Llanos, or reedy plains of Monai, spread within 500 or 600 feet above the level of the shore. The lake of the Caraccas appears to have forced a passage for itself through the quebrada or cleft of Tipe, while that of Aragua has been gradually dissipated by a slow process of evaporation leaving some vestiges of its former existence in pools charged with muriate of lime, and in the low islets called Apa- recidas. The medium height of the Cordillera of the coast is about 4000 or 5000 feet; but its loftiest summit, next to the Sierra Nevada of Merida, is the Silla (or saddle) of the Caraccas, which was visited by Humboldt, and ascertained from barometrical measurement to have an elevation of 8420 feet. Farther to the eastward the mountain chain becomes suddenly depressed, especially its primitive rocks ; the beds of gneiss and mica slate meeting as they advance with accumulations of secondary calcareous substances which envelope them completely, and rise to a great eleva¬ tion. The incumbent mass of sandstone, with a calcareous base, extending from Capelluari, forms a detached range of mountains in which no trace of primitive rock is found. The second branch, which stretches from the Andes across the American continent, and exhibits a chain of primitive mountains, is named by Humboldt the Cordillera of the Cataracts of Orinoco. This very enterprising traveller surveyed it over an extent of upwards of 600 miles, from the Black River to the frontiers of the Great Bara ; but the rest of the chain is very little known, running through un¬ explored wilds and regions almost inaccessible, occupied by fierce and independent tribes of savages. It leaves the great trunk between the 3d and 6th degree of southern la¬ titude, and runs eastward from the Paramo or high desert of Tuquillo and St Martin, and the sources of the Guaviari, rearing the lofty summits of Umama and Canavami, and pouring forth the large rivers Meta, Zama, and Ymerida, which form the roudals or tremendous rapids of Ature and Maypure, the only openings existing at present between the interior of the continent and the plain of the Amazon. Beyond these cataracts the chain of mountains again ac¬ quires greater elevation and breadth, occupying the vast tract inclosed between the rivers Caura, Cavony, and Pa- damo, and stretching southward to the boundless forests where the Portuguese settlers gather that valuable drug the sarsaparilla. Farther eastward this chain is not traced, no European or civilised Indian having ever explored the sources of the Orinoco; all access in that quarter being prevented by the ferocity of the Guaicas, a dwarfish but very fair and warlike race, and by the valour of the Guajaribos, a most desperate tribe of cannibals. Beyond these recesses, however, we are made acquainted with the continuation of the chain of the cataracts, by the astonishing journey per¬ formed by Don Antonio Santos, who, disguised like a savage, his body naked, and his skin stained of a copper colour, and speaking fluently the several Indian dialects, penetrated from the mouth of the Rio Caroni to the Lake of Parime and the Amazon. The range of mountains sinks lower, and con¬ tracts its breadth to 200 miles, where it assumes the name of Serrania de Quimeropaca and Pacaraimo. A few de¬ grees farther eastward it spreads out again, and bends south to the Canno Pirara along the Mao, near whose banks ap¬ pears the Cerro or hill of Ucucuamo, consisting entirely of a very shining and yellow mica slate, which has therefore procured from the credulity of early travellers the magnifi¬ cent appellation of Dorado or Golden Mountain. East from the river Essequibo this Cordillera stretches to meet the granitic or gneiss mountains of Dutch and French Guiana, inhabited by confederated bands of negroes and Caribs, but giving birth to the commercial streams of Ber- bice, Surinam, and Corentin. The chain of the cataracts of Orinoco has only a mean height of about 4000 feet above the level of the sea. The greatest elevation occurs where the mountain of Duida rears its enormous mass from the midst of aluxuriant plain, clothed with the tropical productions of palms and ananas, and dis¬ charges from its steep sides, about the close of the rainy season, volumes of incessant flames. No one has yet had t e resolution or perseverance to climb through the tangling an rampant bushes to its peak, which, measured trigono- metncally, gives an altitude of 8465 feet above the sea. I he whole mountain group which forms this Cordillera is distinguished by the abrupt descent of its south flank; nor is it ess remarkable for containing no rock of secondary ormation, or exhibiting any vestige of petrifactions and or¬ ganic remains. It contains only granite, gneiss, mica slate, Andes, and hornblende, without any casing or admixture of sand- stone or calcareous matter. The third great branch sent out from the trunk of the Andes is that of the (yhir^uttos^ which province it traverses making a sort of semicircular sweep between the parallels of 15 and 20 degrees south latitude, and appearing to con¬ nect the colossal heights of Peru and Chili with the moun¬ tains of Brazil and Paraguay. It supplies the rivers that feed tlm Maranon on the one side, and the Plata on the other. The structure and disposition, however, of the Cor¬ dillera of the Chiquitos still remain almost unknown. These grand chains of mountains divide the southern continent of America, from the latitude of 19 to that of 52 degrees, into three immense plains, which on the west side are shut up by the enormous ridge of the Andes, but are all open on the east, and towards the Atlantic Ocean. The most northern is the • A D E S. most northern is the valley of die Orinoco conristin" of *n?losA^ometimes cinnabar and coal; and another mostly savannahs or level trac, covered^S ^ savannahs or level tracts covered with reedy herbage and scattered palms. The next is the plain of the Maranon which is entirely covered with dense, impenetrable forests. 1 he third and southernmost valley is the Pampas, a dead fiat of most prodigious expanse, clothed, like that of the Ori¬ noco, with a coarse, rank herbage, and abandoned to the oc¬ cupation of countless herds of wild cattle. Of these immense plains, the subsoil resembles the com¬ position of the neighbouring mountains. In the valley of the Orinoco, the primitive rock is generally wrapt in a coat of sandstone, with calcareous cement, or covered with cal¬ careous concretions, which betray the vestiges of recent organic remains, but show none of the older impressions, such as the belemmtes and ammonites, so common in Eu- rope. The woody plain of Maranon is distinguished by the thinness of its soil, and the total absence of any calcareous ingredients, the granite approaching close to the surface, which is in some places left quite bare over an extent of many furlongs. But the Pampas of Buenos Ayres are covered to a great depth with beds of alluvial deposits, in which the powers of vegetation, fomented by the rays of a hurning sun, luxuriate in wanton profusion. I he lake of Titicaca covers a surface of 4000 square miles, being in some places 120 fathoms deep. It has an elevation of 12,795 feet above the sea, and terminates at the mountain Potosi, which rises to 16,000 feet, and is yet covered with the ruins of the ancient Peruvian civilisation. Near this centre the volcano of Arequipa stands, at the height of 18,373 feet, while the double peak of the Nevados, Z Z™1 lI l‘!nan1’ tower to the enormous elevations of •f2 ?And 24,450 feet: or about 3000 feet above the sum¬ mit of Chimborazo, which was long regarded as the loftiest pinnacle of our globe. But, in the northern extension of the Cordillera, Sorata rears its snowy head, at the stupen- of Penriand°n 25,200 feet’ according to the observation In those tropical regions cultivation ascends to very near "l118, 0t l)erPetual snow. Various prolific crops, and daloid ;,ha1ndSSnof°the Teri™'pOTDl'r1’’ ,|ll(0"'e