I f«nu„9.,b labor. | ^ ^ , ^ 4^ 4^ I LIBRARY | IJ OF THE IT I Universityof Illinois. | ^ ^ CLASS. BOOK. VOLUME. ^ - § Accession No ^ ./.^if"-^' v^vlfc'-: ^r^^l^ir'. ■it ^ f f ih i^: i^- i A. T ( J W t_ r '-±- ■if if ^' y jl i. JL J- > ..A r T •if- r f 1 ,f »• 'If "If*" T -•; ■ ir T T ■A y TP v JL -JL. ■A ^ 4^ w T r- !^ 4 ij** 'w^ 4- t IF w T J- T i f JL r * * A # T ^ IT-- f j T > JL. ■f, ' IT" T if 7* 1r t T M +- / -r A r Jf >^ W ■f i- ~ - 4lr -4.- Jr T > * f- * IT- < IF ; • ▼ r- T 4- ■X T T + > r*^ ir ff- * if- 4 Digitized by the Internet Archive in 2015 https://archive.org/details/keytonorthamericOOcoue_0 KEY TO NORTH AMERICAN BIRDS. PRINTED AT THE SALEM PRESS, Corner of Liberty and Derby Streets, Salem, Mass., F. W. Putnam & Co., Proprietors. October, 1872. KEY TO NORTH AMERICAN BIRDS CONTAINING A CONCIfSE ACCOUNT OP EVERY SPECIES OP LIYING AND FOSSIL BIRD AT PRESENT KNOWN EROM THE CONTINENT NORTH OF THE MEXICAN AND UNITED STATES BOUNDARY. ILLUSTRATED BY 6 STEEL PLATES, AND UPWARDS OF 250 WOODCUTS. BY ELLIOTT COUES, ASSISTANT SUKGEOX UNITED STATES ARMY. SALEM: NATUKALISTS' AGENCY. NEW YORK: DODD AND MEAD. BOSTON: ESTES AND LAURIAT. 1872. Entered, according to Act of Congress, in the year 1872, by F. W. PUTNAM AND ELLIOTT COUES, In the Office of the Lil)rarian of CongTcss at Washington. PREFACE. A PREFACE is iiulispoiisahle in this instiiiicc, simply because I iiavc no otiicr opportunity of properly :icknowle(li,kn, of Cambridge, Mass., who has diligently revised nearly all the proofsheets, and whose critical suggestions have proved invaluable. Mr. Robert 11iu(;way, of Illinois, lias given me the benefit of his still unpublished studies of the Jtaptores and some other groups, besides rendering, as Mr. Allen also has, various essential services. Prof. Baird kindly olfered me the use of all the illustrations of his late Review, while Pi'of. Aciassiz generously placed at my disposal the plates accompanying Mr. Allen's Memoir on the Birds of Florida. Several of the woodcuts have been taken from Prof. Tenney's Manual of Zoology, with the author's permission ; and a few otiicrs have been contributed by Messrs. Lee and SiiEPAiiD. With a few exceptions, the rest of the illustrations have been drawn from nature by the author, and engraved bj' Mr. C. A. "Walker. I have spoken elsewhere of Prof. Maush's almost indispensable co62)eration in one part of the work. While material for the greater part of the descriptions has been furnished by the author's private cabinet, the Synopsis could hardly have been prepared witiiout that free access to the collection of the Smithsonian Institution, of which I have been permitted to avail myself. The onl}'' word of explanation that seems to be required is with regard to the large number of genera I have admitted. I have been led into this — unnecessarily, perhaps, and certainly against my judgment — partly by ni}- desire to distui-b a current nomenclature as little as possible, and parti}' because it is still uncertain what value should be attached to a generic name. Among wading and swinnning birds — the groups of which are, on the whole, more precisely limited than those of Imtessoi-es — I have, however, indicated what I consider to be a reasonable reduc- tion ; and on another occasion I should probably extend a like practice, if not one even more " conservative," to the remaining groups. I will only add, that I consider that several of the admitted families of Oscines will require to be mer<;ed in one. These are the Tanlidm, Saxicolidia and S>/Iviida'. if not also the Troglo- chjtidm and JfotaciUido' ; while the same maj- prove true of the current Svlvicoline, Tanagrine and Fringilline groups. E. C. Wasiiin(;tox, D. C, September 9th, 1872. CONTENTS. PAGE. INTRODUCTION 1 Sec. I. OuNiTiioLOGY Defined — Bmus Defined — Brief Desciuption of tdeir Peculiar Covering 1 Sec. 11. An allusion to tue CLASsmCATioN of Birds — Taxonomy — Struc- ture — Characters — Groups of Different Grades — Types and Aber- rations — Equivalency — Analogy and Affinity — Example 7 Sec. III. Definition and brief Description of the Exterior of a Bird. — Parts and Organs — I, The Body: he^u), neck and body proper. — II. The Members : bill, wings, tail, feet 13 Sec. IV. Directions — How to Use the Iusy. — How to Measure a Speci- men, ETC 63 ARTIFICIAL KEY TO THE GENERA 61 SYSTEMATIC SYNOPSIS OF NORTH AMERICAN BIRDS 69 SYNOPSIS OF THE FOSSIL FORMS 347 ADDITIONS AND CORRECTIONS 351 INDEX AND GLOSSARY 353 INTRODUCTION. SECT. I. OimiTiioLoaY Defined — Biuds Defined — Brief Description OF their Peculiar Covering. § 1. Science (Lat. scire, to know) is knowledge set in order; knowledge disposed after the rational method that best shows, or tends to show, the mu- tual relations of observed facts. Such orderly knowledge of any particular class of facts — such methodical disposition of observations upon a nj^ par- ticular set of objects — constitutes a Special Science. Thus, Ornithology (Gr. ornithos, of a bird, logos, a discourse) is the Science of Birds. Or- nithology consists in the rational arraugemcnt and exposition of all that is known of birds. Ornithology treats of the physical structure, physiological processes, and mental attributes of birds ; of their habits and manners ; of their geographical distribution ; of their relations to each other and to other animals. The first business of Ornithology is to define its ground ; to answer the question § 2. What is a Bird? A Bird is an air-breathing, egg-laying, warm- blooded, feathered vertebrate, with two limbs (legs) for walking or swim- ming, two limbs (wings) for flying or swimming, fixed lungs in a cavity communicating with other air-cavities, and one outlet of genito-urinary and digestive organs ; with {negative characters) no teats, no teeth, no fleshy lips, no external fleshy ears, no (perfect) epiglottis nor diaphragm ; no bladder, no scrotum, no corpus callosum ; and with the following collateral characters, mostly shared by more or fewer other animals: — Under jaw hinged with the rest of the skull by means of an interposed movable bone, that is also movably jointed with two bones of the upper jaw ; head jointed with neck by only one hinge ; shoulder-joints connected with each other by a curved bone, the clavicle (with rare exceptions), and with breast-bone by a straight stout bone, the coracoid ; ribs all bony, most of them jointed in the middle as well as with back-bone and breast-bone, and having bony oflsets ; less than three separate wrist and hand-bones ; two fingers, of one or two bones ; head of thigh-bone hinged in a ring, not in a cup ; one of the two leg-bones not forming the ankle-joint ; no sejparate ankle-bones ; less than three sep- arate foot-bones ; two to four toes, of two to five bones, alwaj's ending in claws ; both jaws horny-sheathed and nostrils in the upper one ; feet and toes (when not feathered) horny-sheathed ; three eyelids ; eyeball with hard KEY TO N. A. BIRDS. 1. (1) 2 STRUCTUKE OF TEATHEKS. plates in it, eight muscles on it, and a peculiar vascular organ inside ; two larynges, or " Adam's-apples " ; two bronchi; two lungs, perforated to send air into various airsacs and even the inside of bones ; four-chambered heart, with perfect double blood-circulation ; tongue with several bones ; two or three stomachs ; one liver, forked to receive the heart in its cleft ; gall- bladder or none ; more or less diffuse pancreas, or "sweetbread" ; a spleen ; intestines of much the same size throughout; cceca, or none: two lobulated, fixed kidneys ; two testicles fixed in the small of the back, and snbject to periodical enlargement and decrease ; one functional ovary and oviduct ; outlets of these last three organs in an enlargement at end of intestine, and their products, with refuse of digestion, all discharged through a common orifice. But of all these, and other characters, that come under the head of description rather than of definition, one is peculiarly characteristic of birds; for every bird has feathers, and no other animal has feathers. Naturally, then, we look with special interest upon Feathers : § 3. a. Their Structure. A perfect feather consists of a main stem, or scape (scapus; pi. i, fig. 7, ad), and a supplementary stem or after- shaft (Jiyporhachis ; pi. i, fig. 7, h), each bearing two webs or vanes {vex- illum, pi. vexilla; pi. i, fig. 7,c), one on either side. The scape is divided into two parts; one, the tube or barrel, or "quill" proper {calamus; pi. i, fig. 7, d) is hard, horny, hollow, cylindrical and semitransparent ; one end tapers to be inserted into the skin ; the other ends, at a point marked by a little pit {umbilicus) , in the shaft {rhachis) , or second part of the stem ; the rhachis is squarish, and tapers to a point; is less horny, is opaque, and filled with white pith ; it alone bears the vexilla. The after-shaft has the same structure, and likewise bears vexilla ; it springs from the stem, at junc- tion of calamus and rhachis, close by the umbilicus. It is generally very small compared with the i-est of the feather ; but in a few birds is quite as large ; it is wanting in many ; and is never' developed on the principal wing and tail feathers. The vane consists of a series of appressed, flat, narrowly lance-shaped or linear laminte, set obliquely on the rhachis, and divarica- ting outward from it at a varying angle ; each lamina is called a barb {barba; pi. i, fig. 6, a, a). Now just as the rhachis bears barbs, so does each barb bear its vanes {barbules; pi. i, fig. 6, b, b, c) ; it is these last that make a vane truly a web, that is, they connect the barbs together, so that some force is required to pull them apart. They are to the barbs ex- actly what the barbs are to the shaft, and are similarly given ofi" on both sides of the barbs, from the upper edge of the latter. They are variously shaped, but generally flat sideways, with upper and lower border at base, rapidly tapering to a slender thread-like end ; and are long enough to reach over several barbules of the next barb, crossing the latter obliquely. All the foregoing structures are seen with the eye or a simple pocket lens, but the next two require a microscope; they are barbicels (or cilia; pi. i, fig. TYPES OF FEATHERS. 3 8), and booklets (haimili; pi. i, fig. 8). These are simply a sort of fringe to the barbules, just as if the lower edge of the barbule were frayed out, and only differ from each other in one being plain, hair-like processes, and the other being Jioohed at the end. Barbicels do occur on both anterior and pos- terior rows of barbules ; but rarely on the latter ; booklets are confined to barbules of the anterior series, which, as we have seen, overlie the posterior rows of barbules, diagonally forming a meshwork. The beautiful design of this structure is evident ; by it, the barbules are interlocked, and the vane of the feather made a web ; for each booklet of one barbule catches hold of a barbule from the next barb in front, — any barbule thus holding on to as man}' of the bar- bules of the next barb as it has booklets. To facilitate this interlocking, the bar- bules have a thickened upper edge of such size that the booklets can just grasp it. This is clear- ly illustrated in pi. i. fig. 2, where a, a, a, a are four barbs in transverse section, viewed from the cut surfaces; with their anterior (6, b, b, b), and posterior (c, c, c, c) barbules, the former bearing the booklets which catch over the edge of the latter. b Fig. 2. Sections of a central rigid feailier of tlie Lyre- bird. Natural size; a, from terminal curve; 6, middle portion. FlO.l. Section from loosely barbed feather of Lyre-bird. Natural size. But all feathers do not answer the above description. First, the after-shaft may be wanting, as we have seen ; then, as frequently happens, booklets may not be developed, and barbicels may be few or wanting; barbules may be few or wanting, or so trans- formed as to be only recognized by position, and even barbs themselves may be wanting on one side of the shaft, as in some tail feathers of the famous Lyre-bird, or on both sides, as in certain bristly feathers about the ^ mouth and eyelids of various birds. (Certain unusual styles of feathers are shown in figs. 1, 2, 3.) Con- sideration of these and other modifications has led to the recognition of th'ee § 4. Types of Structure. 1. The feathery (pen- nacm), characterized as above. 2. The downy (plum- ulacea), when the stem is short and weak, with soft rhachis and barbs, with long, extremely slender, mostly thread-like barbules, with little knotty dilatations in place of barbicels, and no booklets. 3. The hairy {Jiloplmnacea) with a thin, stiff calamus, usually no pith in the rhachis, fine cylindrical stiff barbs k'lij.'i. a; siclioii. 1-2 size, from one of tlie external feathers of Lyre-bird; J, single barb. 4 KINDS or FEATHKRS. and barbules, the latter wanting barbicels, knots and booklets. The first two types may be found in different parts of the same feather, as in pi. i, fig. 7, which is partly pennaceous, partly plumiilaceous. All feathers are built upon one of these three plans ; and, though seemingly endless in di- versity, may be reduced to four § 5. Different Kinds of Feathers. 1. Contour-feathers (pennce) have a perfect stem composed of baiTel or shaft, and vanes of pennaceous structure at least in part, usually with downy structure toward the base. They form the great bulk of the plumage, that is upon the surface of a bird, exposed to light ; their tints give the bird's colors ; they are the most vari- ously modified of all, from the fishlike scales of the penguin, to the glit- tering plates of the humming-bird, and all the endless array of tufts, crests, rufis and other ornaments of the feathered tribe ; even the imperfect bristle- like feathers above-mentioned belong here. Another feature is, that they are usually individually moved by cutaneous muscles, of which there may be several to each feather, passing to be inserted into the sheath of the tube, inside the skin, in which the stem is inserted; it is estimated that some birds have twelve thousand of these little feather muscles. Every one has seen their operation when a hen shakes herself after a sand-bath ; and any one may see them plainly under the skin of a goose. 2. Down-feath- ers (pliimuloi), characterized by the plumulaceous structure throughout. These form a more or less complete investment of the body ; they are almost always hidden from view beneath the contour-feathers, like padding about the bases of the latter ; occasionally they come to light, as in the ruff about a condor's neck, and then usually occur where there are no other feathers ; they have an after-shaft or none, and sometimes no rhachis at all, when the barbs are sessile in a tuft on the end of the barrel. They often, but not always, stand in a regular quincunx between four contour-feathers. 3. The semiplumes (^semiplumos) , which may be said to unite the characters of the last two, possessing the pennaceous stem of one and the plumulaceous vanes of the other. They stand among pennse, like the plumulse, about the edges of patches of the former, or in parcels by themselves, but are always cov- ered over by contour-feathers. They are with or without an after-shaft. 4. Filoplumes {filoplumce,) , or thread-feathers ; these have an extremely slen^ der, almost invisible, stem, not well distinguished into barrel and shaft, and no vanes (with rare exceptions), unless a few barbs near the end of the rhachis may be held for such. Long as they are, they are usually hidden by the contour-feathers, close to which they stand as accessories, one or more seeming to issue out of the very sac in which the larger feathers are implanted. They are the nearest approach to hairs that birds have. § 6. Peculiar Feathers. Certain down-feathers are remarkable for continuing to grow indefinitely, and with this growth there is constant break- ing off of the ends of the barbs. These feathers, from being always dusted over with the dry, scurfy exudation or exfoliation from the follicle in which they grow, are called powder doion-feathers. They occur in the hawk, par- PLUMAGE : TRACTS AND SPACES. 5 rot, and gallinaceous ti-ibes, but especially in the heron family, where they are always present, and readily seen as two large patches of greasy or dusty, whitish, matted feathers over the hips and in front of the breast. Their use is not known. § 7. Feather Oil-gland. With comparatively few and irregular ex- ceptions, birds have a singular apparatus for secreting oil with which to lu- bricate and iDolish their feathers. It is a two-lobed, or rather heart-shaped, gland, saddled upon the root of the tail; consisting essentially of numerous slender secreting tubes or follicles, the ducts of which successively iniite in larger tubes, and finally perforate the skin at one or more little nipple- like eminences. Birds press out a drop of oil with their beak, and then dress the feathers with it. The gland is largest in water-birds, which have most need of an impervious coating of feathers, and always present among them : very large in the fish-hawk ; smaller in other land-birds, and want- ing (it is said), among the ostriches, bustards, parrots and some others. (In pi. I, fig. 4, the line 6 points to the oil-gland.) § 8. Development of Feathers. In a manner analogous to that of hair, a feather grows in a little pit or pouch formed by inversion of the der- mal layer, and is formed in a closed oval follicle consisting of an inner and outer coat separated by a layer of fine granular substance. The outer layer, or "outer follicle " is composed of several thin strata of nucleated epithelial cells ; the inner is thicker, spongy and filled with gelatinous fluid ; a little artery and vein furnish the blood-circulation. The inuer is the true matrix of the feather, evolving from the blood-supply the gelatinous matter, and resolv- ing this into cell nuclei ; the granular layer is the formative material. The outer grows a little beyond the cutaneous sac that holds it, and opens at the end ; from this orifice the future feather protrudes as a little, fine-rayed pencil point. During subsequent growth the follicular layers undergo little further change ; it is the granular that becomes the fe:ither. § 9. All a bird's feathers, of whatever kind and structure, taken together, constitute its ptilosis or Plumage. (a.) Feathered Tracts and Unfeathered Spaces. With the exception of certain birds that have obviously naked spaces, as about the head, etc., all would be taken to be fully feathered. So they are fully covered with feath- ers ; but it does not follow from this, that feathers are implanted everywhere upon the skin. On the contrary, this is the rarest of all kinds of feather- ing, though it occurs, almost or quite perfectly, among the penguins and toucans. Let us compare a bird's skin to a well-kept park, part woodland, part lawn ; then where the feathers grow is the woodland ; where they do not grow, the lawn ; the former places are called tracts {lUerylm) ; the latter spaces {apteria) ; they mutually distinguish each other into certain definite areas. Not only are the tracts and spaces thus definite, but their size, form and arrangement mark whole familii^'' or orders of birds, and so are impor- 6 CHANGES OF PLUMAGE. tant for purposes of classification. They have been specially studied, named aud classified by the celebrated Nitzsch, who has laid down the following as the general plan obtaining in the vast majority of birds : — (6.) 1. The spinal or dorsal tract {pteryla spinalis, pi. i, fig. 4, i), running along the middle of the bird above from nape of the neck to the tail ; subject to great variation in width, to dilation and contraction, to forking, to sending out branches, to interruption, etc. 2. The humeral tracts {pt. Jiumerales, pi. i, fig. 4,2), always present, one on each wing; narrow bands running from the shoulder obliquely backward upon the upper arm- bone, parallel with the shoulder-blade. 3. The femoral tracts (^pt. femo- rales, pi. i, fig. 4,3), a similar oblique band upon the outside of each thigh, but, luilike the last, subject to great variation. 4. The ventral tract {pt. gastrcei^ pi. i, fig. 3,8), which forms most of the plumage on the under part of a bird ; commencing at or near the throat, and continued to the anus ; it is very variable like the dorsal tract, is usually bifurcate, or divided into right and left halves with a central apterium, is broad or nar- row, branched, etc. ; thus, Nitzsch enumerates seventeen distinct modifica- tions ! The foregoing are mostly isolated tracts, that is, bands neai'ly surrounded by aptcria that are complementary to them ; the following are continuously, uniformly feathered, and therefore, in general, equivalent to the part of the body they represent. Thus, 5, the head tract {pt. capitis, pi. I, figs. 3, 4; 4, 4), clothes the head and generally runs into the beginning of both dorsal and ventral tracts. 6. The wing tract (^pt. alaris, pi. i, figs. 3, 5 ; 4, 5), represents all the feathers that grow upon the wing, except those of the humeral tract. 7. The tail tract {pt. caudalis, pi. i, figs. 3, g; 4, e), includes the tail feathers and their coverts, those surrounding the oil-gland, and usu- ally receives the termination of the dorsal, ventral, and femoral tracts. 8. The leg tract (pt. cruralis, pi. i, figs. 3, 7 ; 4, 7) , clothes the legs as far as these are feathered, which is sometimes to the toes, generally only to the heel. I need not give the spaces, as these are merely the complements of the tracts ; and the highly important special feathering of the wings and tail will be examined in describing those members for purposes of classification. § 10. Progress and Change. Newly hatched birds are covered with a kind of down, entirely different from the feathers they ultimately acquire. It is scanty, leaving much of the body naked, in Altrices, or those birds that are reared by the parent in the nest ; but thick and puffy in a few of these, and in all JPrcecoces, that run about at birth. But true feathers are soon gained, in some days or weeks, those of wings and tail being the first to sprout. The first plumage is usually only worn for a short time — then another is gained, and frequently several more changes ensue before the bird attains its mature covering. Feathers are of such rapid growth, that we can easily understand how exhaustive of vital energies the growth must be, and how critical a pe- riod the change is. The renewal of plumage is a process familiar to all under the term " moult " (ecdi/sis) . It commonly occurs at least once a year, and generally twice, in spring and fall ; when old, faded and worn out feathers CLASSIFICATION. 7 are shed, and fresh ones take their place, either over a part or the whole of the body. The change frequently or generally results iu considerable differ- ences of color, constituting the "seasonal plumages" of so many birds, which, in the same bird, may change from black to white even, from plain to variegated, from dull to brilliant. But birds also change colors, by actual alteration in the tints of the feathers themselves, and by gaining new ones without losing any old ones. The generalization may be made, that when the sexes are strikingly difiereut in color, the young at first resemble the female ; but when the old birds are alike, the young are different from either. "When the seasonal changes are great, the young resemble the fall plumage of the old. "When the old birds of two different species of the same genus are strikingly alike, the young of both are usually intermediate between them, and difterent from either. Besides being the most highly developed, most complex, wonderfully per- fect and beautiful kind of tegumeutary outgrowth ; besides fulfilling the obvious design of covering and protecting the body, the plumage has its § 11. Pectiliar Office: that of accomplishing the act of flying. For all vertebrates, except birds, that progress through the air — the flying-fish with its enlarged pectoral fins ; the flying reptile (Draco volans) with its skinny parachute ; the flying mammal (bat) with its great webbed fingers — accomplish aerial locomotion by means of tegumentary expansions. Birds, alone, fly with tegumentary outgrowths, or appendages. SECT. U. An allusion to the Classification of Birds — Taxon- 031Y — Structure — Characters — Groups of Different Grades — Types and Aberrations — Equivalency — Analogy and Affinity — Example. Seeing what a bird is, and how distinguished from other animals, our next business is to find out how birds arc distinguished from each other ; when we shall liave the material for § 12. Classification, a prime object of ornithology, without which, birds, however pleasing they are to the senses, do not satisfy the mind, which always strives to make orderly disposition of things, and so discover their mutual relations and dependencies. Classification presupposes that there are such relations, as results of the operation of fixed inevitable law ; it is, therefore, § 13. Taxonomy (Gr. taxis, arrangement, and nomas, law), or the ra- tional, lawful disposition of observed facts. Just as taxidermy is the art of fixing a bird's skin in a natural manner, so taxonomy is the science of arranging birds themselves in a natural manner, according to the rules that, to the best of our knowledge and belief, arc deducible from examination of their § 14. Structure : The physical constitution of a bird ; all the material constituents of a bird, and the way its parts or organs are put together. 8 CLASSmOATlON. Internal structure, or anatomical structure {ana, aud temnein, to cut), so called because we have to cut into a bird to see it, comprehends all the parts of a bird that are ordinarily hidden from view ; external structure, those that lie exposed to view upon the surface. Much time has been wasted in arguing the superiority of one or the other of these for purposes of classifi- cation ; as if a natural classification must not be based upon all points of structure ! as if internal and external points of structure were not reciprocal and the mutual exponents of each other ! External points of structure stand to internal somewhat in the relation of interest and cajiital ; it is legit- imate and wise enough to use interest only unless we need to draw upon capital. In our greater taxonomic enterprises — in the founding of our higher groups — we require all the capital we can get; in our lesser under- takings the interest alone is sufficient. Moreover, birds are so much alike in their anatomical structure, that this answers taxonomic purpose only for higher groups ; and practically, at any rate, we make our lesser divisions so readily from external structure, that this may be said to furnish inost of our § 15. Zoological Characters. A "character" is any point of struct- ure whatsoever that is susceptible of being perceived and described for the purpose of distinguishing birds from each other. Characters are of all grades, or values, from the trivial ones that separate two species, to the fundamental ones that mark ofi" primary divisions. The more characters, of whatever grade, that birds have in common, the more closely they are allied to each other, and conversely. The possession of more or fewer characters in common, results in § 16. Degrees of Likeness. Were all birds alike, or did all birds difler by the same characters to the same degree, no classification would be possible. But we find that they vary within wide limits — from the almost imperceptible difiereuce between two hatched in the same nest, to the extreme unlikeuess between a thrush and a penguin. This is the arena of classification : this gives us both the room and the material to divide birds into groups, and subdivide these into other groups, of greater or lesser " value," or (/j-acZe, according to the more or fewer characters shared in common. We saw that (in addition to other characters) , all birds have feathers, which no other animals possess ; birds can be separated from other animals, but not from each other, by this feature ; it is therefore a class character. Even the § 17. Primary Division of birds must be made from a character of less value than this. A broad generalization upon the sum total of all the ex- hibitions that (recent — geologically) birds make in their modes of life, shows that these are of three sorts. Either birds habitually live above the earth, in the air or on trees ; or they habitually live on the ground ; or they habitually live on the water ; and in each case, their structure was designed and fitted for such particular end. We have, therefore, at the outset three tyjpes of structiLre correspondent with, and equivalent to, three plans of life; and, if our observations are correct, aud our reasoning not fallacious, these ORDERS, FAMILIES, 9 types or plans, seeruiugly an abstract induction of ours, are as real as the birds themselves. It is natural then to divide birds into three primary groups: Aerial Birds {Aves Aereoe), Terrestrial Birds {Aves Terrestres) and Aquatic Birds (Aves Aquaticce) . An illustration will make this clear. Men build machines to transport themselves and their goods ; the only known media of transportation are the air, the earth and the water ; and we do not imagine any sort of vehicles more unlike than a balloon, a buggy, and a brig ; these, therefore, exemplify the most fundamental division of machines for transportation. § 18. Orders. Taking any one of these tj'pes of structure, we find that it may be unfolded, or carried out, in different ways. Studying all known aquatic birds, for example, we see that their plan of life is fulfilled in four difi"erent ways ; it is exhibited under four aspects, or modes of execution, each distinguished by some particular combination of aquatic characters with certain other characters that we did not take into account in framing our Aves Aquaticce. Thus a goose, a gannet, a gull and a guillemot, all agree in aquatic characters, but difier from each other by each having certain characters that the other thi-ee lack. Characters marking such modes of ex- hibition are called ordinal; and the groups so organized, Orders. In our illusti-ation, there are likewise four plans of aquatic machines ; diving bells, sailing vessels, steamships and rowboats, clearly distinguished by the way in which motion (the prime function of all vehicles) is effected ; in this case it is by weight, by wind, by steam, by muscle ; therefore the machinery by which these forces are applied, furnishes ordinal characters of aquatic vehicles. § 19. Families. But all the birds of an order are not alike ; some re- semble each other more than they do the rest ; so another set of groups must be made. These groups are called Families; they consist in a certain combination of all ordinal characters with special sets of characters of the next lower grade or value. Let x represent the sum total of strictly ordi- nal characters, and suppose we find these variously combined with a certain number of the next lower grade of characters, as a, b, — -f for instance ; then the particular combination x (abc) is one f\imily ; x (bef) another ; x (cde) another, etc., and we shall have as many families under an order as there actually are such combinations. Sometimes an order may be represented by X (a. . . f) ; then there is but one family, as, for example, in the aquatic order Lamellirostres where the Anaiidce alone furnish every one of the ordi- nal features, and are equivalent to the order; that is to say (a . . .f) =x, because no character from a to y is wanting in any member of the order. In our order sailing vessels, of aquatic machines, masts and sails are ordi- nal characters, because they are essential apparatus to catch the wind. But these may be of a varying number, etc., upon which we might found families of sailing-vessels, as the ship family, represented by x (three masts -|- square sails) ; the schooner family x (two masts -|- fore-and-aft sails) ; the sloop family x (one mast -|- fore-and-aft sails), etc. Diving bells, I sup- KEY TO N. A. BIUDS. 2 10 GENEKA, SPECIES, VAKIETIES. pose, are so much alike, that they might be called an order of aquatic machines of but one family. § 20. Genera. After family manifestations of ordinal characters, we come to the modifications of families themselves, enquiring how many Icinds of difference {genus, a kind, pi. genera) there are in the birds composing a family. The mode of determining genera in a family is precisely like that of determining families in an order ; it is a; again (this time representing fam- ily characters) into a varying number or combination of characters of the next lower grade, a — f. A genus is the last definite grouping of birds that is usually recognized ; it may be defined as the ultimate essential modifica- tion of structure (ultimate, because there is none lower; essential, because trivial features do not constitute a genus; of structure, because mere size, color, etc., ai-e only specific characters). In the ship family, the three- masted vessel, full-rigged, with square sails, is a genus (ship-proper) ; one with square sails on two masts only, and fore-and-aft sails on the mizzen, is another genus (bark), and so on. Genera are composed of one or more § 21. Species. The definition of a species has become difficult of late years, but for present purposes we may assume that it is any one of the constant exponents of a genus, comprehending all the birds that bear to each other the relation of parent and offspring ; the latter capable of repro- ducing ' each after its kind' and maintaining certain characters to an evident degree peculiar to itself. Resting, then, upon this, we have little else to consider before we reach that most imquestionable fact, an individual bird. Species, however, are not absolutely constant; they vary in size, color, etc., within certain limits, under influences not always comprehended as yet, but which seem a part of that universal tendency in nature toward the produc- tion of essential unity in diversity ; the operation of which, if completely effective, would level distinctions and abolish difference in sameness. § 22. A Variety is a step in this direction; for, although it may seem an opposite step, yet departure from any given jDoint or standard must be approach toward some other. A variety is {generally) distinguished from a species by its tendency to revert to its original stock, or, diverging fur- ther from that, to approach some other type. The former case is constantly being demonstrated, and the latter is probably susceptible of being proven ; but in either case, inconstancy is a marked feature of varieties. Varieties apparently produced by diflerence in food, climate, etc., are called local races, when restricted to a small area in or around the general distribution of the parent stock ; geographical races, when more widely separated over large areas. A hybrid is a cross between two species, almost always of the same natural genus. Hybrids are generall}^ infertile, while crosses between mere varieties are capable of reproduction, so that hybridism becomes in some measure a test ; nevertheless, exceptions are not wanting. § 23. Intermediate Groups. Having arrived at the individual bird, we will retrace our steps for a moment, for the student must sooner or later learn, that, easy as it seems to theoretically determine the foregoing groups. IXTEKMEDIATE AND ABERRANT GROUPS. 11 there are many difficulties in the way of their practical definition. This is partly because all birds are singularly inter-related, presenting few broad, unequivocal, unexceptional characters in tha midst of numberless minor modifications, and partly because the higher groups, no less than species and varieties, shade into each other. In our ilhistration, for example, we find exactly intermediate aquatic machines ; thus, it would be difficult for a landsman to say whether an hermaphrodite brig belonged to the ship family, or the schooner family ; he would have to decide according as he considered number of masts, or shape of sails, the more essential family character. But the intermediate groups which remain to be examined are not of this ambiguous nature ; they ai'e unequivocally referable to some particular group of the next higher grade, and, being subordinate divisions, they are distin- guished by the prefix s«<6,'as sub-order, sub-family. Though somewhat difficult to define, they are, I think, susceptible of intelligible, if not always precise, definition. A sub-group of any grade is framed, without taking into consideration any new or additional characters, upon the varying prom- inence of one or more of the characters just used to form the group next above. In our formula above x {cihc) for a certain family of the order x, suppose the family character a to be emphasized, as it were, and to pre- dominate over h and c, to the partial suppression of these last : then a sub- family of X {abc) might be expressed thus: — x {Abe) ; and it is further evident, that there will be as many sub-families as there are groups of birds in the family representing varying emphasis of a, or h, or c; as a; (a B c), x (a b C), etc. While we take account of neio characters of another grade, in forming our successive main groups, in our sub-groups, then, we recog- nize only more or less of the same characters. But the distinction is not always evident; nor is it observed so often as, perhaps, it should be. § 24. Tvpicvii AND Aberrant Groups. Waiving what might be rea- sonably argued against considering any group specially " typical " of the next higher, we may define a convenient and frequent term : — The ti/pical genus of a family, or family of an order, is that one which develops most strongly, or displays most clearly, the more essential characters of the next higher group, of which it is one member. And in proportion as it fails to express these in the most marked manner, either by bearing their stamp more lightly, or by having it obscured or defaced by admixture of the characters of a neighboring group, does it become less and less typical (" subtypical ") and finally aberrant. Suppose the ordinal symbol x, as before, to represent the sum of various ordinal characters, more or less essential to the integrity of the order : then obviously, the family characters abc, or def may be com- bined with a varying value of x; thus, x^ (abc) or x^ {def) and the formula of the typical family would be {a—f). Thus, it is characteristic of most thrushes {Turdidoi) to have the tarsus booted, but all do not have it so; therefore, in subdividing the family, we properly make a division into thrushes with booted tarsi, and thrushes with scutellated tarsi ; the former are typical of the family, the latter sub-typical or even aberrant. » 12 AFFINITY AND ANALOGY. § 25. Equivalence of Groups. It may sound like a truism to say, that groujDS of the same grade, bearing the same name, whatever that may be, from sub-class to sub-genus, must be of the same value ; must be distin- guished by characters of equal or equivalent importance. Equivalence of groups is necessary to the stability and harmony of any classilicatory sys- tem. It will not do to frame an order upon one set of characters here, and a family upon a similar set of characters there ; but order must differ from order, and family from family, by an equal or corresponding amount of dif- ference. Let a group called a family differ as much from the other families in its OAVu order as it does from some other order, and it is by this very fact no< a family, but an order itself. Let the orders of birds stand apart a yard, say ; if, then, any families, so-called, stand as far apart, they are not families. It seems a simple proposition, yet it is too often ignored, and always with ill result. Two points should be remembered here : first, that the absolute size or bulk of a group has nothing to do with its grade ; one order might contain a thousand species, and another only one, without having its ordinal value disturbed. Secondly, any given character may be of different value in its application to different groups. Thus, number of primaries, whether nine or ten, is a family character almost throughout Oscines; but in one Oscine family, Vireonidce, it is scarcely a generic feature. It is difficult, however, to determine such a point as this last without faithful training in ornithology. § 26. Affinity and Analogy. Birds are Allied, or affined, according to the number of like characters they employ for like purposes ; they are ana- logically related according to the number of unlike characters that they use for similar purposes. A loon and a cormorant, for instance, are closely affined, because they are both fitted in the same way for the pursuit of their prey under water. A dipper (family CmcUdce), and a loon (family Coli/mbidce) , are analogous, because they both pursue their prey under water ; but they stand almost at the extremes of the ornithological system ; they have almost no affinity beyond their common birdhood ; totally different structure is only modified for the same ends, that are thus brought about by totall}^ different means. So the wings of a butterfly, a bat, and a bird are analogical, be- cause they subserve the same purpose in each case ; needless to add, these creatures have no affinit}^ § 27. With this cursory glance* at some taxonomic principles I pass to a brief explanation of modifications of external characters alone ; some knowl- edge of which is necessary to the slightest appreciation of ornithological definitions and descriptions. I shall confine myself mainly to consideration of those that the student will need to understand in order to use the present *As the present occasion obviously affords no opportunity for an adequate discussion of the classification of birds, it is hardly necessary to say to ornithologists, that here I simply assume a class Jves comi)osed of recent birds, as an initial step, without consideringthe broader generalizations deducible from extinct forms; and that I speak of species and varieties, in the sense in which these terms are commonly used, waiving the biological questions involved. EXTERIOR OF A BIRD. 13 volnme easily and successfully. Here, however, I will insert a tabular illus- tration of the foregoing remarks : — Class AVES: — Birds. (Sub-class* Insessores: — Perching Birds.) Order Passeres : — Passerine Perchers. (Sub-order Oscines: — Singing Passerines.) Family f Turdid^e : — Thrushes. (Sub-family f Mimince: — Mocking Thrushes.) Genus X Mnius : — Mockers. (Sub-genus J Mimus: — Typical Mockers.) Species % poltglottus : — Many-tongued. ( Vari ety caudatus ': — Long-tailed . ) SECT. ni. Defixitiox axd brief Description of the Exterior of A Bird. — Parts axd Organs — I. The body : head, keck and body proper. — II. The members: bill, avings, tail, feet. § 28. The Contour of a bird with the feathers on, is spindle-shaped, or fusiform, tapering at both ends ; it represents two cones, joined base to base at the middle, or greatest girth of body, tapering in front to the tip of the bill, behind to the end of the tail. Obvious design: easiest cleavage of air in front, and lessening of drag or wash behind. But this shape is largely produced by the lay of the plumage ; a § 29. Naked -Bird presents several prominences and depressions; this ir- regular contour is reducible, in general terms, to tico double cones. The head tapers to a point in front, at the tip of the bill ; and nearly to a point behind, towards the middle of the neck, in consequence of the swelling mus- cles by which it is slung on the neck ; from the middle of the somewhat contracted or hour-glass shaped neck, this last enlarges toward the body, by the swelling of the muscles b}- which it is slung to the body ; the body then tapers to the tail. The § 30. Exterior of a Bird is divided into seven parts : 1, head {caput), 2, neck (collum), 3, body (truncus), 4, bill (rostrum), 5, wings (alee), 6, tail (cauda), 7, feet (pedes) : 1, 2, 3, are collectively called "body," in dis- tinction to 4, 5, 6, 7, which are members. The * Intermediate groups are in italics and parentheses. t Familien now always end in -ida, and snb-famllies in -inm, a very convenient distinction, since we thus always, know the rank designated by words so ending. X a bird's scientific name now iN VAKlAnr.y consists of two words — the genus and the species, the former first, the latter last: thus, Mimus polyylottus ; but we may, if we wish, interpolate the sub-genus in parentlie- ses, and afHx the variety with sign var. : thus, ArimiiH (Arimua) poli/r/lottan, vnv. caudtitus. Generic names are alwnyn written with a capital; specific names, according to the rules of the British Association, now gen- erally followed, .should never be, though it is customary to so write those tliat are derived from the nnmcs of persons and places, as well as all substantive appellations. 14 HEAD, NECK, BODY. § 31. Head has the general shape of a 4-sided pyi^amid ; of which the base is applied to the end of the neck, and does not appear from the exte- rior ; the uppermost side is more or less convex or vaulted, sloping in every direction, and tajiering in front; the sides proper are flatter, more or less perpendicular, and taper in front ; the bottom is likewise flattish and simi- larly tapering. The departures from this typical shape are endless in degree, and variable in kind ; they give rise to numerous general descriptive terms, as "head flattened," "head globular," etc., but these are not susceptible of precise definition. The sides pi'esent each two openings, ei/es and ears; their position is variable, both absolutely and in respect to each other. But in the vast majority of birds, the eyes are strictly lateral, and near the mid- dle of the side of the head, while the ears arc behind and a little below. Exceptions : — owls have eyes "anterior;" woodcock and snipe have ears be- low and not behind the eyes. The mouth is always a horizontal fissure in the apex of the cone ; there are no other openings in the head proper, for the nostrils are always in the bill. The §32. Neck, in eftcct, is a simple cylinder: rendered somewhat hour- glass shaped as above stated. Its length is variable, as is the number of bones it has. Bearing the head with the bill, which is a bird's true hand, it is unusually ^e,c I 1 J? il TT 1 Ti 1 • vnc-n: c, nasal fossa; d, nostril; e, the skull. Ihe SCallold Ot the Under mandible is a (see below);/, gape, or wliole com- missural line ; f/, rictus; h, connnis- compound bone called inferior maxillary; it is U-, or '"iamSIs'on.nde?^^^^^^^^ VI T •«: », «ps of mandibles, bones, with certain accessory bones of the upper mandible, as the palate bones, etc., together with the horny investment, constitute the Jaws. Both jaws, in birds, are movable; the under, by the joint just mentioned; the upper, either by a joint at, or by the elasticity of the bones of, the forehead ; it is moved by a singular muscular and bony apparatus in the palate, further notice of which Would involve anatomical details. When closed, the jaws meet and fit along their opposed edges or surfaces, in the same manner, and for the same purposes, as the lips and teeth of man or other 24 DIFFERENT KINDS OF BILLS. vertebrate animals. All bills, thus similarly constituted, have been divided* into § 45. Four Classes, representing as many ways in which the two man- dibles close upon each other at the end. 1. The epignalhous (Gr. ej)i, upon, gnathos, jaw) way, plan, or type, in which the upper mandible is longer tlian the under, and its tip is evidently bent down over the tip of the lower. 2. The hypognathous (Gr. hypo, under), in which the lower mandible is longer than the other. 3. The jKtragnaihoits (^Gv. para, at or by), in Avhich both are of about equal length, and neither is evidently bent over the other. 4. The melagnathoiis (Gr. mela, with, beside, etc.), in which the points of the mandibles cross each other. The second and fourth of these are ex- tremely rare ; they are exempliticd, respectively, by the skimmer and the cross-bill (genera 295 and 60). The lirst is common, occurring through- out the birds of prey, the parrots, and among the petrels, gulls, etc., etc. The great majority of birds exhibit the third ; and among them, there is such evident gradation into cpignathism, that it is necessary to restrict the latter to its complete development, exhibited in the intermaxillary bone di- vested of its horny siieath, wliich often, as among flycatchers, etc., forms a little overhanging point, but does not constitute cpignathism. These classes, it should be added, though always applicable, and very convenient in de- scriptions, arc purely arbiti-ary, that is, they by no means correspond to any four primary groups of birds, but on the contrary, usually only mark families and the subdivisions of families ; and the four types may be seen in contiguous genera. The general shape of the bill has also furnished § 46. Other Classes, for many years used as a large basis for ornitho- logical classification ; but which the progress of the science has shown to be merely as convenient as, and only less arbitrary than, the foregoing. The principal of these are represented by the following types : — A, among land birds. 1. The fissirostral, or cleft, in which the bill is small, short, and with a very large gap running down the side of the head, as in the swallow, chimney-swift, whippoorwill. 2. The temiirostral, or slender, in which the bill is small, lo7ig, and Avith a short cleft; as in the humming-bird, creeper, nuthatch. 3. The denlirostral, or toothed, in which, with a various gen- eral shape, there is present a nick, tooth, or evident lobe in the opposed edges of one or both mandibles near the end ; as in the shrike, vireo, and some wrens, thrushes and warblers. 4. Tlie conirostral, or conical, suffi- ciently defined by its name, and illustrated by the great finch family and some allied ones. B, among water birds. 5. The longirostral, or long, an aquatic style of the tenuirostral, best exhibited in the great snipe family. 6. Tha pressirostral, or the compact, illustrated by the plovers, etc., and quite likely analogous to the conirostral. 7. The cultrirostral, cutting, perhaps analogous to the deutirostral, exemplified in the heron group. None of these are now used to express natural groups, in strict definitions; all are * By the wi itei- : Proc. Acad. Nat. Sci. Pliila., Dec. 18G0, p. 213. VARIOUS FORMS OF BILLS. 25 conveuieut iucideuttil terms in general descriptions. Various other lesser terms, expressing special moditications, as lamellirostml, acuiirostml, etc., are employed ; but all are best used, now, as common, not as proper names, simply descriptive of § 47. Other Forms. A bill is called lonr/, when notably longer than the head pi'oper ; short, when notably shorter ; medium, in neither of these con- ditions. It is comj)ressed, when higher than wide, at the base at least, and generally for some portion of its length ; depressed, when wider than high ; terete, under neither of these conditions. It is recurved, when curved up- ward ; decurved, when curved downward ; bent, when the variation in either direction is at an angle ; straight, when not out of line with axis of the head. A bill is obtuse (said chiefly of the paragnathous sort) when it rapidly comes to an end that therefore is not fine ; or when the end is knobby ; it is acitfe when it runs to a sharp point; acuminate, when equally sharp and slen- derer; attenuate, when still slenderer; subulate (awl-shaped), when slen- derer still; acicular (needle-shaped), when slenderest possible, as in some humming-birds. A bill is arched, vaulted, turgid, tumid, inflated, etc., when its outlines, both crosswise and lengthwise, are notably more or less convex: and contracted, when some, or the principal, outlines are concave (said chiefly of depressions about the base of the upper mandible, or of con- cavity along the sides of both mandibles) . A bill is hamidate (hooked) or unguicidate (clawed), when strongly epignathous, as in rapacious bijixls, where the upper mandible is like the talon of a carnivorous beast ; it is den- tate, when toothed (§ 46), as in a falcon; if there are a number of sim- ilar "teeth," it is serrate (like a saw); it is cultrate (knife-like) when ex- tremely compressed and sharp-edged, as in the auk, skimmer; if much curved as well as cultrate, it is falcate (scythe-shaped) ; and each mandible may be oppositely tiUcate, as in the cross-bill. A bill much flattened and widened at the end (rare) is spatulate; examples : spoonbill, shoveller duck. One is called lamellate, when it has a series of plates or processes just inside the edges of the mandibles ; as in all the duck order, and in a few petrels ; the design is to furnish a sifter or strainer of water, just what is effected in the whale, by the ''bone" in its mouth. Finally, the far end of the bill, of what- ever shape, is called the tijp or apex (fig. 5, n) ; the near end, joined to the rest of the skull, the base; the rest is the continuity. Some other features of the bill as a whole are best treated under separate head of § 48. The coverixg of the bill, (a.) In the great majority of birds, including nearly all perchers, many walkers and some swimmers, the sheath- ing of the mandibles is wholly hard, horny or corneous; it is integument modified much as in the case of the nails or claws of beasts. In nearly all waders and most swimmers, the sheath becomes, wholly or partly, softer, and is of a dense, leathery texture. But some swimmers, as among the auks, furnish bills as hard-covered as any, while some perchers have it partly quite soft, so that no unexceptional rule can be laid down; and, moreover, the gradations from one extreme to the other are insensible. Probably, KEY TO N. A. IJIHDS. 4 26 COVERING or THE BILL. the softest bill is found among the snipes, where it is skinny throughout, and in typical snipes vascular and nervous at the tip, becoming a true organ of touch, used to feel for worms out of sight in the mud. In all the duck order, the bill is likewise soft; but there it is always terminated by a hard, horny "nail," more or less distinct; and such horny claw also occurs in other water birds with softish bills, as the pelican. An interesting modification occurs in all,, or nearly all, of the pigeon order ; these birds have the bill hard or hardish at tip and through most of continuity, but towards and at the base of the upper mandible the sheath changes to a soft, tumid, skinny texture, overarching the nostrils ; it is much the same with most plovers. But the most important feature in this connection is afforded by the parrots and all the birds of prey ; one so remarkable that it has received a distinct name : — Cere. The cere (L. cera, wax ; because it looks waxy) is a dense membrane saddled on the upper mandible at base, so different from the rest of the bill, that it might be questioned rather it does not more properly belong to the head than to the bill, were it not for the fact that the nostrils open in it. Moreover, the cere is often densely feathered, as in the Carolina pari'oquet, in the bill proper of which no nostrils are seen, these being hidden in the feathered cere, which, therefore, might be easily mistaken, at first sight, for the bird's forehead. A sort of false cere occurs in some water birds, as the jaegers, or skua-gulls (genera 280 and 279). The tumid nasal skin of pigeons is sometimes so called ; but the term had better be restricted to the birds first above named. The under mandible probalily never presents softening except as a part of general skinniness of the bill. (b.) The covering is either entire ov pieced. In most birds it is entire; that is, the sheath of either mandible may be pulled off whole, like the finger of a glove. It is, however, in many birds divided into parts, by various lines of slight connection, and then comes off in pieces; as is the case with some water birds, particularly petrels, where the divisions are regular, and the pieces have received distinctive names. The entire cover- ing of both jaws together, is called rhcwvpJiotheca ; of the upper alone, rhin- otheca; of the under, gnathotheca. (c.) The covering is otherwise variously marked: sometimes so strongly, that similar features ai-e impressed upon the bones themselves beneath. The most frequent marks are various ridges (L. pi. carincB, keels) of all lengths and degrees of expression, straight or curved, vertical, oblique, hor- izontal, lengthwise or transverse ; a bill so marked is said to be striate or carinate; when numerous and irregular, they are called rugoe (L. ruga, a wrinkle) and the bill is said to be corrugated or rugose. When the eleva- tions are in points or spots instead of lines, they are called pimctce; a bill so furnished is punctate, but the last word is oftener employed to designate the presence of little pits or depressions, as in the dried bill of a snipe, towards the end. Larger, softish, irregular knobs or elevations pass under the general name of warts or papiUce, and the bill so marked is papillose; when the processes are very large and soft, the bill is said to be carunculate SPECI.VL PARTS OF THE UNDER MANDIBLE. 27 (L. caro, flesh, dimimitive canaiculus, little bit of flesh). Various linear depressions, ofteu but uot always associated with carinte, arc grooves or sulci (L. sulcus, a furrow) aud the bill is then sulcate. Sulci, like carinjE, are of all shapes, sizes and positions ; when very large aud definite, they are some- times called canaliculi, or channels. The various knobs, "horns," aud large special features of the bill cannot be here particularized. Any of the fore- going features may occur on both mandibles, and they are exclusive of that special mark of the upper, in which the nostrils open, and which is consid- ered l)elow (§ 51). We have still to notice the special parts of either mandible ; and will begin with the simplest, the § 49. Under Mandible. In the majority of birds it is a little shorter and a little narrower and not nearly so deep as the upper ; but sometimes quite as large, or even larger. The upper edge, double (^. e. there is an edge on both sides), is called the mandibular tomium (Gr. temnein, to cut; fig. 5, J), as far as it is hard; this is received against, and usually a little "within, the corresponding edge of the upper mandible. The prongs already mentioned (§ 44) are the mandibular rami (pi. of L. ramus, a branch; fig. 5, i) ; these meet at some poiut in front, either at a short angle (like >) or with a rounded joining (like ^ ). At their point of union there is a promi- nence, more or less marked (fig. 5, ^•) ; this is the gonys (corrupted from the Gr. gonic, a knee ; hence, any similar protuberance). That is to say, this point is gonys proper ; but the term is extended to apply to the whole line of union of the rami, from gonys proper to the tip of the under mandible ; and in descriptions it means, then, the under outline of the bill for a corres- ponding distance (fig. 5, I). This important term must be constantly held in mind. The gonys is to the under mandible what the keel is to a boat. It varies greatly in length. Ordinarily, it forms, say, one-half to three- fourths of the under outline. Sometimes, as in conirostral birds, a spaiTow for example, it represents nearly all this outline ; while in a few birds it makes the whole, and in some, as the puffin, is actually longer than the lower mandible proper, because it extends backwards in a point. Other birds have almost no gonys at all : as a pelican, where the rami only meet at the extreme tip, or in the whole duck family, where there is hardly more. As the student must see, the length of the gonys is simply a matter of the early or late fusion of the rami, and that similarly, their mode of fusion, as in a sharp ridge, a flat surface, a straight line, a curve, etc., results in corresponding modifications of its special shape. The interramal sjDace (§ 41, c). is complementary to length of gonys: some- times it runs to the tip of the bill, as in a pelican, sometimes there is next to none, as in a puffin ; while its width depends upon the degree of diver- gence, and the straightness or curvature of the rami. The surface between the tomium and the lower edge of rami and gonys together is the side of the under mandible (fig. 5, m). The most important feature of the § 50. Upper Mandible is the cidmen (Lat. for top of anything; fig. 5, h). The culmen is to the upper mandible what the ridge is to the roof of a 28 SPECIAL TARTS OF THE UPPER MANDIBLE. house ; it is the upper profile of the bill — the highest middle lengthtvise line of the hill; it begins where the feathers end on the forehead, and extends to the tip of the upper mandible. According to the shape of the bill it may be straight or convex, or concave, or even somewhat co -shaped; or double- convex, as in the tufted puffin : but in the vast majority of cases it is con- vex, with increasing convexity towards the tip. Sometimes it rises up into a thin elevated crest, as well shown in Crotophaga (gen. 126) and in the puffins, Avhen the upper mandible is said to be heeled, and the culmeu it- self to be cultrale; sometimes it is really a furrow instead of a ridge, as toward the end of a snipe's bill ; but generally it is simply the uppermost line of union of the gently convex and sloping sides of the upper mandible (fig. 5, a). In a great many birds, especially those with depi'cssed bill, as all the ducks, there is really no culinen ; but then the median lengthivise line of the surface of the upper mandible, takes the place and name of culmen. The culmen generally stops short about opposite the proper base of the bill ; then the feathers sweep across its end, and downwards across the base of the sides of the upper mandible, usually also obliquely backwards. Variations in both directions from this standard are frequent ; the feathers may run out in a point on the culmen, shortening the latter, or the culmen may run a way up the forehead parting the feathers ; thus either in a point, as in the I'ails and gallinaceous birds, or as a broad plate of horn, as in the coots and gallinules. The lower edge (double) of the upper mandible is the maxillary tomium, as far backward as it is hard and horn}'-. The most con- spicuous feature of the upper mandible in most birds is the § 51. Nasal Fossa (L. fossa, a ditch), or nasal groove (fig. 5, c), in which the nostrils open. The upper prong of the intermaxillary bone (§ 44) is usually separated some ways from the two lateral ones ; the skinny or horny sheath that stretches betwixt them is usually sunken below the general level of the bill, especially in those birds where the prongs are long or widely separated; this "ditch" is what we are about. It is called fossa when short and wide, with varying depth ; sulcus or groove when long and narrow ; the former is well illustrated in the gallinaceous birds ; the latter in nearly all wading birds and many swimmers. When the prongs are soldered throughout, or are very short and close together, there is no (or no evident) nasal depression, and the nostrils open flush Avith the level of the bill. The § 52. Nostrils (fig. 5, d) vary in position as follows : — they ai'e lateral when on the sides of the upper mandible (almost always) ; culminal when together on the ridge (rare) ; superior or inferior when evidently above or below midway betwixt culmen and tomia ; they are hasal, when at the base of the upper mandible ; sub-basal when near it (usual) ; median when at or near the middle of the upper mandible (frequent, as in cranes, geese, etc.) ; terminal when beyond this (very rare ; and probably there are now no birds with nostrils at the end of the bill, except the Apteri/x). The nostrils are pervious, Avhen open, as in nearly all birds ; impervious, when not visibly open, as among cormorants and other birds of the same order ; they are THE XOSTPilLS AND NASAL FOSSiE THE GAPE. 29 perforate "when there is uo septum (partition) between them, so that yon can see through them from one side of the bill to the other, as in the turkey- buzzard, crane, etc. ; imperforate when partitioned off from each other, as in most birds; but different ornithologists use these terms interchangeably. The principal shaj^es of the nostrils may be thus exhibited : — a line, linear nostrils ; a line variously enlarged at either end, davate, diih-shaped, ob- long, ovate nostrils ; a line, enlarged in the middle, oval or ellijitic, nostrils ; this passing insensibly into the circle, round or circular nostrils; and the various kinds of more or less linear nostrils may be either longitudinal, as in most birds, or oblique, as in a few ; almost never directly transverse (up and down). Eounded nostrils may have a raised border or rim; when this is prolonged they are called tuhidar, as in some of the goatsucker family, and in all the petrels. Usually, the nostrils are formed entirely by the substance surrounding them, thus, of cere, in a hawk, of softish skin, in a pigeon, plover or snipe, or of horn, in most birds; but often their contour is partly formed by a special development somewhat distinct either in form or texture, and this is called the nasal scale. Generally, it forms a sort of overhanging arch or portico, as well shown in all the gallinaceous birds, among the wrens, etc. A very curious case of this is seen in the European wryneck {Ljnx torquilla) , where the scale forms the floor instead of the roof of the nostrils. The nostrils also vary in hQ.\\\g feathered or naJced; the nasal fossa being a place where the frontal feathers are apt to run' out in points (called antice) embracing the root of the culmen. This extension may completely fill and hide the fossa, as in many grouse and ptarmigan ; but it ofteuer runs for a varying distance toward, or above and beyond the nostrils ; sometimes, similarly below them, as in a chimney- swift ; and the nostrils may be densely feathered when there is no evident fossa, as in an auk. When thus truly feathered in varying degree, they are still open to view ; another condition is, their being covered over and hidden by modified feathers. These are usually bristle-like {setaceous), and form two tufts, close-pressed, and directed forwards, as is perfectly shown in a crow; or the feathers may be less modified in texture, and form either two tufts, one over each nostril, or a single ruff, embracing the whole base of the upper mandible ; as in nuthatches, titmice, redpoll linnets, snow buntings and other northern Frinr/illido}. Bristles or feathers thus growing forwards arc called retrorse (L. retrorsum, backward ; here used in the sense of in an opposite direction from the lay of the geuei-al plumage ; but they should properly be called antrorse, i. e., forward). The nostrils, whether culminal or lateral, are, like the eyes and cars, always two in number, though they may be united in one tube, as in the petrels. § 53. The Gape. It only remains to consider Avhat results from the re- lations of the two mandibles to each other. When the bill is opened, there is a cleft, or fissure between them ; this is the i/«j;e or rictus (L. rictus, mouth in the act of grinning) ; but, while thus really meaning the open space between the mandibles, it is generally used to signify the line of their 30 THE AVINGS THEIR BONY FilAMEWOHK, closure. Commissure (L. commilteve, to put or join together) means the point where the gape ends behind, that is, the angle of the mouth, where the opposed edges of the mandibles join each other ; but as in the last case, it is loosely applied to the whole line of closure, from true commissure to tip of the bill. So we say, "commissure straight," or "commissure curved ; " also " commissural edge " of either mandible (equivalent to "tomial edge") in distinction from culmen or gonys. But it would be well to have more precision in this matter. Let, then, lomia (fig. be the true cutting edges of either mandible from tip to opposite base of bill proper, rictus (fig. 5, g) be their edges thence to the point commissure (fig. 5, h) where they join when the bill is open ; the line commissure (fig. 5,/) to include both when the bill is closed. The gape is straight, when rictus and tomia are both straight and lie in the same line ; curved, sinuate, when they lie in the same curved or waved line ; angulated, when they are straight, or nearly so, but do not lie in the same line, and therefore meet at an angle. (An important distinction. See imder f^imily Fringillidoi in the Synopsis.) The Wings. § 54. Definition. Pair of anterior or jyectoral limbs organized for flight by means of dermal outgrowths. Used for this purpose by birds in general ; but by ostriches and their allies only as outriggers to aid running ; by penguins as fins for swimming under water ; used also ' in the latter capacity by some birds that fly too, as divers. Wanting in no recent birds, but imperfect in a few. To understand their structure we must notice § 55. Their Bonv Framework. (Fig. 6.) This ordinarily consists of nine actually separate bones ; but there are several more that fuse together. The ai-m-bone, humerus, a single bone, reaches from shoulder to elbow ; it is succeeded by two parallel bones, idna and radius, of about equal lengths, reaching from elbow to wrist, forming the forearm, cubit or antibrachimn. The wrist {carpus) has two little knobby carpal bones, called scapholunar and cuneiform; very early in life there is another, the mag- num, that soon fuses with the hand-bone, or metacarpal. At first, this last is of three bones, corresponding to those of our hand that support our fore, middle and ring finger respectively ; afterwards they all run together. The one corresponding to the middle finger is much the largest of the three, and it supports two finger-bones (j^halaiiges) placed end to end, just as our three similar finger-bones are placed one after the other at the end of their own hand-bone. The forefinger hand-bone sticks out a little from the side of the principal one, and bears on its end one finger-bone (sometimes two), which is commonly, but wrongly, called the bird's "thumb." For although on the extreme border of the hand, it is homological with the forefinger ; birds have no thumb (exc. Archmopteryx, Struthio, Rhea) ; and no little finger. The third hand-bone is joined to the second, and bears no finger- bone. STRUCTURE OF THE WING. 31 § 56. The Mechanisji of these bones is admirable. The shoulder- joint is loose, much like ours, and allows the humerus to swing all about, though chiefly up and down. The elbow-joint is tight, permitting only bending and unbending in a horizontal line. The finger bones have scarcely any motion. But it is in the wrist that the singular mechanism exists. In the first place, the two forearm bones are fixed with relation to each other so that they cannot roll over each other, like ours. Stretch your arm out on the table ; without moving the elbow, you can turn the hand over so that either its palm or its back lies flat on the table. It is a motion (rotation) of the bones of the forearm, resulting in what is called pronation and su- pination. This is absent from the bird's arm, necessarily ; for if the hand could thus roll over, the air striking the pinion-feathers, when the bird is flying, would throw them up, and render flight difiicult or impossible. Next, the hinging of the hand upon the wrist is such, that the hand does not move up and down, like ours, in a plane perpendicular to the plane of the elbow-bend, but back and forwards, in a plane horizontal to the elbow ; it is as if we could bring our little fin»er and its side of the hand around to touch the corresponding border of the forearm. Thus, evidentl}^, extension of the hand upon the wrist-joint inci'eases and completes the unfolding of the wing that commenced by straightening out the forearm at the elbow. There is another essential feature in a bird's wing. In the figure, 6, abc represents a deep angle formed by the bones, but none such is seen upon the outside of the wing. This is because this triangular space is filled up by a fold of skin stretched over a cord that passes straight from near a to c. But A and c approach or recede as the wing is folded or unfolded, and a simple cord long enough to reach the full distance a — c would be slack in the folded wing ; so the cord is made elastic, like an India rubber band ; it stretches when the wing is unfolded, and contracts when the wing is shut ; it is thus always hauled taut. The cord makes the always straightish and smooth anterior border of the wing. The carpus c, or the always promi- nent point of the anterior border, is a highly important landmark in de- scriptions, and should be thoroughly understood ; it is also called the "bend of the wing." (See under Directions for Measurement; see also explana- tion of fig. 6.) Fig. 6, taken from a young chicken (right wing, upper surface), shows the composition and mechanism of a bird's wing, a, shoulder; b, elbow; c, wrist or carpus; d, tip of prin- 32 MECHANISM OF THE WING. cipal (the third) finger; ab, arm; bc, forearm; CD, pinion, or hand, composed of c, carpns, theuce to e, mctacarpxis or hand proper, except the bone i, this, and kd, being diyils or fin- gers, a, shaft of humerus; b, uhia; c, radius; d, scapholunar bone; e, cuneiform bone; these last two composing wrist or carpus proper. Now tlie figure (1) marks two lines that run to the two ends of the humerus, designating a sort of cap on eillier end of that bone ; this cap is an kpipiiysis;* both ends of ulna and radius show similar epiphyses, connected in the figure, as in case of the humerus, with the shaft by waved lines. Then, of the meta- carpus, (J and / are the epiphyses of, respectively, the two principal metacarpal bones k, the tliird, and Z, the fourth; k and I have not yet coalesced together, but lie simply opposed to each other, whereas their epiphyses themselves, g and /, are seen nearly fused together. h, which seems to be the epiphysis of i, is not; it is a metacarpal itself (the second), bearing the digit, i; it is nearly soldered with g, in wiiicli its epiphysis is already ab- sorbed. Later in life, k sends a plate-lil