-LIBRARY OF THE UNIVERSITY Of ILLI NOIS ?R2o o in CO CVJ NAFURAL HISTORY Digitized by the Internet Archive in 2011 with funding from University of Illinois Urbana-Champaign http://www.archive.org/details/onmorphologyofduOOpark /, birds that seem to be, both sorts of them, the modified descendants of Marsh's Hesperornis. However this may be, the Alcidas are quite as nearly akin on one side to the Penguins as they are on the other to the Loons and Grebes ; and there is this initial difficulty with regard to their relationship * Sec "On the Wings of the Common Fowl": Philosophical Transactions, 18S8, Plates LXII.-LXV., pp. 385-398. f Quarterly Journal Geological Society, 1869, pp. 12-31. % Loc. cit., pp. 30-31. Me. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 3 to any actual descendants of Hesperornis, that in that huge toothed bird the pre-sacral vertebrae are all " cylindroidal " in their articulation ; whereas the Alcida-, like the Penguins and the Gulls, have their dorsals " opistho- ccelous." In this they are just a step above Marsh's Ichthyornis, which has its pre-sacral in a very low stage, namely, " amphicoelous," a condition that is not quite lost in the existing Laridae. To complicate the subject still more, as if to keep the way of the tree of descent, Professor Huxley has already classified the Alcidre and the Laridae together. They are put with the Petrels (Procellariidoa), birds whose dorsals are cylindroidal, like those of Hesperornis, the Grebes, and the Loons.* But the true position and genealogy of the duck tribe (Anatidae) presents as tough a problem as the auk tribe (Alcidae) ; we have, here, a faggot of tough problems, that will task the ingenuity and strength of two or three generations of biologists. The structure of the skull in the duck-tribe is so similar to that of the fowls, in all things at first, and in many things permanently, that I have only taken up that part of the skeleton after it has acquired all the true anatine characteristics, namely, in the nearly ripe embryo of Cygnus nigri- collis. For I had long ago worked out the skull of the common fowl, the early stages of which illustrate so accurately those of a duck, goose, or swan. f The skull of the guillemot ( Uria troile), my example of an alcine skull, is worked out as early as the third stage in the chicken (op. cit., Plate LXXXII.) The swan's early stage corresponds with one between the fourth and fifth stages in the chick (op. cit., Plates LXXXIIL, LXXXIV.). In the rest of .the skeleton the more jDrimitive condition of the parts has been worked out in the embryo duck. In these parts I have gone down far below the morphology of the adult Iguanodon, and have, as I believe, unconsciously thrown some light upon its development, for that huge beast was highly specialized. It had got a long way from its amphibian ancestors : its size, as well as its peculiar "hind-quarters," attest this. * See his Classification of Birds, Proceedings, Zoological Society, 1867, pp. 457, 458. f See Fowl's Skull, Philosophical Transactions, 1869, Plates LXXXL-LXXXVII. pp. 755-807. [1*] 4 Cunningham Memoirs. The Morphology of the Anatih^;.* The Cranium in Cj/gnus. The intense ossification seen in birds makes this part of the skeleton a "closed book" in the adult; embryos, near the time of hatching, are the most profitable for interpretation of the various parts, and for comparison with what is found in the skull of other types. The two extremes of cranial structure in those hot-blooded Sauropsida are to be found, on one hand, in the Tinamou, which retains many of its sutures, and has one, or even two, rows of supra-orbital scale bones ; and, on the other, in a Passerine bird, where the metamorphosis of a skull, essentially reptilian, lias reached its utmost perfection. The ectocranium of the nearly ripe embryo of Cygnus nigricollis (Plate III., figs. 1— G, and Plate IV.) has most of its sutures open, and remains of those that arc closing. These bones are very massive for a bird, and have a struthious coarseness about them : in the adult bird this is greatly altered by the absorption of much of the diploe, for the sake of pneumaticity. The facial splints, as compared with those of the chick, are very broad ; for we have in these " lamellirostres " (or sifters) a spoon-shaped bill, not ending insensibly in a more or less hooked point, but in a neat "unguis" like a finger-nail, and adapted to the flatter part in the mandible, like a thumb to a finger-nail in us. The premaxillaries (px.), as in osseous fishes, dominate the upper face : they form three-fourths of the spoon- shaped " rostrum," and are already ankylosed in the foremost third. Unlike mammals, the bird has long "nasal processes" to its premaxil- larium — long, narrow splints, that run backwards between the nasals, and overlap the forehead. Laterally (Plate IV., p. n.) the dentary margin, covered with a false dentition of horny lamina?, overlaps the maxillary (;».?-.), and reaches to the jugal bar (,/., q. j-). The notch between these processes is rounded, and a similar notch in the nasal (;?.) finishes behind a large * See, on this subject, Dr. E. 0. Cunningham's Paper " On the Steamer Duck [Micropterus rinereus) " : Ti ansactions, Zoological Society, vol. vii., Plates LV11I.-LXIL, pp. 493-501. Mk. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 5 oval space, in which is seen the alinasal folds (al. n.) and external nostril (e. n.). Already we have come across two agreements between the anatine and the gallinaceous skull, the hidden position of the maxillary like its counterpart, the " os mystaceum" of the perch, and the large oval space in which the nasal vestibule is exposed; these birds are both " holo- rhiual." The AlcidaB, as we shall see, are " schizorhinal," the nasals not being notched behind, but split. In the Anatidos the fore-part of the skull is very peculiar ; the lachry- mal or pre-orbital region is unusually long (see Plate III.). The nasals (n.) have a very large frontal plate, and the " hinge " is in front of that plate, not at the posterior edge of the nasal bones. They become thinned down and elastic where the motion is recpiired. The lachrymals (7.) here attain their greatest size, and have the longest suture above ; they then become nar- row and are hooked backwards below, and help, by their hind margin, to enclose the very open orbit. In the fore palate the premaxillaries (see Plate III., fig. 1, p.v.) have a short palatine process that binds upon the inner edge of the maxillaries (mx.) ; the median region is taken up by the huge temporary prenasal part of the intertrabecula (pi.); half the dentary edge is formed by the maxillary, overlapped by the premaxillary ; each palatine process (or maxillo-palatine, mx. p.) runs inwards and backwards, approximating, be- hind, to its fellow ; and then, ending in a rough point, they diverge to embrace the vomer at its thickest part. This latter bone is a flat vertical spatulate plate, with its broad end behind ; pointed somewhat there, it is again fixed between the sharp styloid "ascending processes" of the palatine (Plate III., figs. 1 and 5, v., pa.). At present the vomer is only composed of one centre ; another appears on the antero-superior corner afterwards (Plate II., fig. 15, v.). The vomer, palatines, and pterygoids belong to the mid-palate ; a pre-palatine bar, however, runs far forwards, wedged into a deep notch in the maxillaries. These large, long bones (pa.) form the lateral boundaries of the nasal passages, which open at their hinder part in one common median " posterior nostril." Their widest part is near the angle of the upper jaw ; they narrow in, sinuously, to their end ; they approximate then, and send forwards and upwards their sharp ascending 6 Cunningham Memoirs. process. The "middle nasal openings" are between the vomer and the palatines. The next bones are the pterygoids (pff.). They are only one third the length of the palatines, which are wedged into their fore-part below; whilst the pterygoids form a peg in front, which is fitted into the upper face of each palatine. This is a curious doubly-pegged joint, which is imperfectly developed in the fowl tribe ; their palatines and vomer are very slender, and the pterygoid peg is not so small and neat ; it is styloid. Nevertheless these two families agree in having a truly azygous vomer, and in not having this pterygoid peg segmented off and fused with the palatine, as in most birds. Also in the small epipterygoid process of the pterygoid, in the breadth of its fore end, and in the fact that it articulates with the basi- pterygoid processes of the basis cranii at its front third, the geese and fowls agree. For, in most birds, when these parts are developed, the articulation is at the middle of the pterygoid : in the struthious birds, Tinamous, and in the embryo of Opisthocomus, it is at the end. Although the palatines and pterygoids, because of their histological de- velopment, are here classed with the parts of the " ectocranium," they are in reality degenerated einIo-crama\ tracts that have lost their cartilaginous pith. Behind the palate, under the broad hind-part of the endocranium, there are three tracts of parosteal bone that at an early stage became fused together as one tract this bony growth is the " parasphenoid " ; the three parts are the " basi-temporals " behind, and the " rostrum " in front (Plate III., figures 1 and 5, pa.s., s., r.b.s., b.t.).* Of all birds the fowls and the duck tribe have the basi-temporals most massive ; this is well seen in the goose, and in Tetrao urogallus. The parasphenoid is generally, not always, in one piece in the Ichthyopsida ; it sometimes has a separate centre in front in certain frogs, f It grafts itself on the basis cranii, aborting the cartilage, in some of the Urodela.J In birds which have a certain amphibian stigma§ in many parts of their organization, * Fowl's Skull, Plate LXXXIL, fig. 2. f Philosophical Transactions (1881), Plates V. and VIII. J Transactions, Linnean Society, series ii. (Zoology), vol. ii., Plates XVII. and XX. § In the existing reptiles the parasphenoid is but little developed. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 7 this grafting of a " parostosis " on the basal cartilage, thus taking the place of a normal endoskeletal bony centre, takes place very early ; and the three primary centres, fused into one, support, in front, the interorbital wall, then develop large " anterior tympanic recesses," and, behind, form most of the thick but excavated basicranial floor (see Plate III., figs. 1 and 5, r.b.s., b.t, a.t.r., and Plate IV.). The basi- temporal mass, a transverse tract bulging forwards at the middle, lies on a lower plane than the fore-part ; in a deep chink between the two masses, the eustachian tubes (eu.) converge towards each other. I have already spoken of the articulation of the basi-pterygoids with the pterygoids ; this takes place in a remarkable manner,* for a new plate of cartilage is developed on both bones ; in the Struthionidaef the pterygoids acquire an articular plate of cartilage, but the basi-pterygoids are direct outgrowths of the basis cranii, and their articular facet is formed by an arrest in the process of ossification of the outgrowth, as in Lizards. This shows how far the fowls and the goose tribe have travelled from those archaic birds — the Struthionidae and their immediate allies. The cheek, in this and most birds, is very feeble, and is funned of three overlapping splints, the foremost of which is a mere outgrowth of the maxillary, its jugal process. This is overlapped by a separate style of the same size, the jugal (/.) ; and under and within these the quadrato- jugal (q.j-) binds the whole together to the quadratum (>].) ; it is one-third longer than the jugal, and is hooked inwards behind, where it is articu- lated to the quadrate. These parts are true parostoses, and are extremely unlike their broad counterparts in the Crocodiles and Tortoises, and in Hatteria. The roof-bones and temporal plates add three pairs more to the cate- gory of parostoses; the foremost of these are the f rentals (/.), which are the largest bones in the skull, and are yet extremely deficient above and over the orbits. A large " fontanelle " still exists at the part where the small hole is seen in Lizards — the orbit of their median eye ; in old geese this fontanelle remains, sometimes bringing the bird near the Lizard, but * Sec Fowl's Skull, he. cit., Plate LXXXIII. f Philosophical Transactions, 18G6, Plates VII. -XV. 8 Cunningham Memoirs. the organ itself is very little developed in birds. The parietals (p.) are of small axial extent in the Anatidse, as in the Ruminant and Cetacean Mammalia ; they meet the frontals, are overlapped laterally by the squa- mosals (•$'/.)> an( l overlap the supraoccipital (s. o.). The squamosals (sq.) are roughly pentagonal bones that overlap the frontals and parietals at their junction, binding the supraoccipital (s. o.) behind, and forming an cave over the auditory recess. The rest of the osseous centres belong to the endocranium. These are transforming the massive " chondrocranium," a remarkable beaked struc- ture, with a short, wide, cranial basin. This has to be described before the bony tracts. Much of this can be seen from below (Plate III., fig. 1), and has also to be surveyed on its side (Plate IV.); its end (Plate III., fig. 3) from above (Plate III., fig. 2), and in a section taken longitudinally and vertically, a little to the left of the mid-line (Plate III., fig. 5) ; thus the crested and rostrate fore-part is seen from its side, and not in section. The occipital base, sides, and plane show that this part is a bulging and oblique hindwall ; it also forms the hindmost part of the floor. The auditory capsules (cat.) are very large, and are jammed in obliquely between the occipital arch and the sub-transverse posterior sphenoids. At present the notochord (nc) forms the axis of the basi- occipital bone (5.0.) ; it has shrunk from its extension into the posterior clinoid wall (Plate III., fig. 5, j>//-), and now forms only the axis of the hindmost cranial segment. Right and left, it was enclosed in the " parachordal " cartilages, which becoming alate laterally, and their wings meeting over the myelon, formed also the hinder skull basin and its end wall, i.e. alisphenoids (a.Ls.), exoccipitals (e. o.) and supraoccipital (s. /), it runs rapidly into the floor of the skull behind, and right and left. Together, this grafted bone, and the superficial growths — which form the anterior tympanic recesses, and the basi-temporal plate — produce in the bird, whose skull is so thoroughly pneumatic, very complex tympanic outworks, as complex as those of the crocodile,* but of a different type. As in those osseous fishes that have a high skull, the pituitary floor is open; it is finished by the parasphenoid ; the internal carotids (i.e.) enter the skull through this space, creeping over the basitemporal plate, whose diplbe forms a bony tube for each artery. At present the pinched-up anterior sphenoid (o. s., p. s.) is unossified ; but the perpendicular ethmoid (p. c.) is a large slab of bone behind the notch for the hinge, larger than the notch. The auditor)/ sense-capsules, like the olfactory, are built into the cranium, and have to be described as parts of it, although they have no original right to this position. These parts are very large, and each carti- laginous capsule, which is planted like a bulb in the side wall of the hind skull, soon coalesces with the proper cranial walls. These oval capsules are tilted backwards, so as to lie supine, and almost in a horizontal position (Plate III., fig. 5). The upper part of each capsule is occupied with the three semicircular canals (a. s. c, p. s. c, h. s. c), and under the arch of the anterior canal there is a recess like that for the "flocculus cerebelli " in * Transactions, Zoological Society, vol. ii., 1'latcs LXII.-LXXI. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 13 the Mammal. The hyena, or rudimentary cochlea, is buried in the basi- latcral cartilage (Plate III., fig-. 1) over the hind edge of the basitemporal plate. The recess, or " meatus interims " for the seventh and eighth nerves (vii., viii.) is shallow, the meatus externus is membranous and very short, and the tympanic cavity is formed by the utilization of many parts round the primary tympanic (or 1st) clef ((see Plate IV.). In front, the large quadrate bone (q), mistaken by our ancestors for the tympanic, and mistaken for it still by those who are not cmbryoloyists, forms the front wall of the porch. Its floor is formed by the basitemporal, its inner wall by the auditory capsule, and its roof and sides by the squamosal. Sometimes there is one, sometimes more than one, six even, true tympanic bones.* I find no separate tympanic in the Anatidae ; but in the duck the floor and sides approximate, closing in the cavity, all but a narrow chink ; this structure is seen still better in the green woodpecker ( Gecinus viridis).~f In that bird this secondary tympanum is like a small Cowrie shell [Trivia). Pound the meatus interims ^ Plate III., fig. 5, vii., viii.) a considerable oblong bone, the periotic (pro.), is already formed; the opisthotic (op.) is seen behind and below; a chink separating it from the exoccipital (e. o.) ; it is a much smaller bone ; externally it joins the delicate bar that separates the fenestra ovalis from the/, rotunda. The epiotic is not seen here, and is rare in birds. There are three visceral arches developed in a bird ; the palatine extension forwards — a part of doubtful morphology — I have already described as the pterygoid and palatine membrane bones : bones that had no true cartilaginous model. The proper pier of the mandibular arch, the quadrate (q), is well developed ; it is much more like that of an amphibian than the quadrate of a serpent or a lizard. It is indeed developed distinctly from the chon- drocranium, and does not coalesce with it at any part ; but it has a large " pedicle," or orbital process, and a large " otic process " with two condyles, as in the Peristeropodous Gallinaceous birds, and in most of the Carinatse. The quadrate has already a large bony shaft ; the pedicle and the articular regions are still soft. That bone corresponds to the upper piece of a branchial arch, with only two segments; that is its true nature: it is * Transactions, Zoological Society, vol. ix., Plates LV., in Corvus corone. f Sec Transactions, Linnean Society, second series (Zoology), vol. i., Plate II., fig. '2. 14 Cunningham Memoirs. a " pharyngo-epihyal." The core of the mandible is a cerato-hypohyal (Plate IV. and Plate III., fig. 4, ar. mlc). Here let it be noticed that the posterior and internal angular processes (p.a.p., i.a.p.) are parts of this " articulo-meckelian " bar; these processes are unusually developed in the cultrirostral fowl, and in these lamellirostrcs, also in that lamellirostral relation of the Ibis, the Flamingo. The cartilaginous rod (mk.) runs inside the dentary splint (d.) nearly to its end; and the kinship of the trabecule to the visceral arches is nowhere more plainly suggested than in this stage of the bird ; that, however, is a knotty problem. There are two layers of bone covering this rod, a deep and a superficial layer. The deep deposit is the ectostcal " articulare" ; its endosteal part has not yet appeared; the superficial or parosteal bones are the dentary (. 47'J. Mr. W. K. Paekee. — Morphology of the Duck and the Auk Tribes. 21 the next following rib. The .sacral and caudal regions of embryo clucks in earlier stages than this (Plate II., figs. 1-3) will be described with the hip girdle. In the second stage cygnets of G. olor, fourteen and fifteen inches long, and about a month old, there are many important changes to be noticed in the vertebral chain . In the atlas (Plate V., figs. 2, 2a, 3, at.) the two centres of the neural arch are united above, and a considerable deposit of bone has taken place in the base; that basal piece, however, is not the true centrum, but an occipito- atlantal " inter- centrum " (i.e.). The centrum, proper, of the atlas has become fused with that of the axis {ax.) to form its odontoid process, as in us ; it is now a considerable bony mass inside the thick odontoid pivot of this peculiar cranio-vertcbral articulation. The atlas is proccelous, but in most land and water birds the cup is deeply notched for the pivot; in many of the nobler arboreal birds the cup is complete, save for a small hole through which the odontoid ligament passes to tie the process to the basis cranii. The back of the atlas fits to the front of the axis by an almost flat-faced joint, but this is not an articulation of centrum with centrum, but of the first and second inter-centra dislocated in some degree through the arrest and tilting of the borrowed atlantal centrum or odontoid process. Under and behind that process, in that part of the base of the axis which binds on to the atlas below, another inter-centrum is seen ; whilst the proper centrum (c.) of the axis is behind both the bony tracts seen in this second vertebra. Only post-zygapophyses are seen in the atlas, both pre- and post-zygapophyses in the axis and all the rest of the pre-sacrals. Also the hinder face of its centrum fits on to the next in the same manner as all the remainder of the pre- sacrals; the joint is " cylindroidal," the centra seeming to be convex behind, whilst in reality they are concave. A vertical section (fig. 2a) corrects what the horizontal section (fig. 4) seems to show ; of course we have the exact opposite of this in the fore-face of each centrum. Thus the fore-face of a normal ornithic centrum, as is well seen in wide, flat vertebra 3 , is a convex condyle that rolls in the rounded groove of the one in front of it. This joint, assisted by the yoking processes or zygapophyses, allows, with perfect 22 Cunningham Memoirs. safety to the myelon, a very considerable amount of mutual movement between vertebra and vertebra. But this is only part of 'this delightful piece of animal mechanics. There is an annular meniscus interposed between the contiguous cartilaginous surfaces in this synovial joint (fig. 4) ; and this part being annular allows the suspensory ligament (s.l.) to pass from one to the other; this ligament is nothing more than the old notochord. But even this is not a full account of the care with which nature has provided for the bird, in the structure of its neck — which is indeed its one arm. As I have already mentioned, the vertebral arteries burrow their way along the sides of the centra in the neck ; and behind the axis, in all birds, the riblet finishes a tunnel right and left at the fore end of each vertebra. Here, as in the great Ratita?, the topmost cervicals, the atlas and axis have, like so many reptiles, ribs up to the occiput. There was no bony riblet in the first stage (Plate IV.) ; here, in these cygnets, there is a small ossification right and left on both these bones. That on the atlas (figs. 2, 3, c.r. 1 ) is a short needle of bone formed in a costal part of cartilage that had become imperfect. That on the axis (fig. 2. c.r. 2 ) isquite normal, like those that follow : it is a bony wedge pointing backwards, and is part of the costal band that ties together the upper and lower transverse processes. I have mentioned that in the herons and some other birds there is an anteroinferior bridge to several of the cervicals (6 or 7) for the protection of the carotids. The ribs do not fasten their " capitulum " between two centra, as in us ; and they have a synovial joint for both capitulum and " tuberculum." The latter is a gliding, the former a cup-and-ball, joint (Plate V., fig. 4, r., e.). Thus everything in the skeleton of birds is carried to its uttermost perfection. They, not we, are, in respect of bodily movements, the crown- ing forms of creation. The dorsal vertebrae differ little from the last cervical (Plate IV., c.r., d.v.): the primary dorsal region, however, has been largely taken in, to form the fore-part of the long sacrum (Plate V., fig. 11): the avian sacrum is four regions in one. Finding how close the Anatidse come to the Ratitse in many things, Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 23 notwithstanding their aquatic habits, and feeling sure that the very term " Ratitaa," as ordinal, is a mistake — a misleading term — I shall now show how near these forms, the duck-tribe and the ostrich-tribe, come together in the structure of their vertebral chain. Both have cylindroidal pre-sacrals, and both have ribs on the atlas and axis. Finding (from my son, Professor T. J. Parker*) that the intercentra of the atlas and axis were the same as in the Carinatas, I looked for them in a ripe embryo of the rnooruk (Casuarius Bcnnetti).^ That embryo is as large as the cygnets a month old, and as much developed: its three foremost vertebra; (Plate IX., figs. 13—15) and its pelvis % show this. The sectional view (Plate IX., fig. 15) shows that the odontoid process (od. p.) leans over the atlantal intercentrum (i.e.), and is scooped below where that intercalary element fits in. Then, again, by a remarkable adaptation the second intercentrum (i.e.) comes close behind the first; and the proper centrum of the axis only forms two-thirds of that compound vertebra. The two opposed intercentra are narrow transverse plates of bone, half as wide across as the contiguous centra. The cartilage is imperfect over the vertebral artery in the atlas (at.), and the riblet is not yet ossified: that on the axis (ax.) is also small, at present, but is embedded in cartilage : that on the third (c.v. 3.) is much larger. The common Casso- wary§ has no ossified atlantal rib, nor has the Rhea ;|| but the Emu ^] lias it well marked on both sides. In Stmlhio** it is seen on one side only. So that in these forms the atlantal ribs are less constant than in the Anatidse ; and it is worth noticing that in the swans the sacrum has one or two vertebra? more than in the giant African ostrich, which has only twenty. -\\ The sacral vertebras of the cygnet (Plate V., fig. 11) do not correspond with * An exhaustive memoir on the morphology of the Apteryx has been prepared by him, and will see the light, in the Philosophical Transactions, as soon as the present Paper, f See Zoological Transactions, vol. iv., Plate LXXIL J Philosophical Transactions, 1888, B., Plate LXV., figs. 8-10. § Mivart, Transactions, Zoological Society, vol. x., p. 28, fig. 23. || Ibid., p. 3, fig. 3. f Ibid., p. 17, fig. 14. ** Ibid., vol. viii., p. 388, fig. 2. ff Ibid., Transactions, Zoological Society, vol. viii., p. 420. 24 Cunningham Memoirs. what I find in very old specimens. I will therefore give the vertebral for- mula of each of my stages : — — C. D. D. S. L. S. S. U. S. Cd. Cygnus nigricollis, embryo '24 5 4 3 4 11 G + 5 ,, olor, one month old . 25 5 3 4 4 in 6 + 5 olor, aged .... 25 5 4 3 4 10 7 + 5 Thus, whilst the two first have sixty-two vertebra? in all, the third has sixty-three ; and there is a difference in each case as to the number in the different regions. A little overgrowth of bony deposit, in the case of the black-necked swan, would give it twenty-three sacrals, as its first caudal is partly between the ilia. This great number of vertebra? in the Cygnince may be adaptive : it is manifestly Reptilian. The great length of the thorax in these heavy wide-bodied birds has necessitated the development of three or, mostly, four pairs of ribs in the dorso-lumbar region : in a large number of birds there is only one pair. The gentle manner in which the individual vertebra? are modified as they pass from one region to another is well seen in this stage (Plate V., fig. 11). The lines of fusion of the vertebral elements in the embryo are still cartila- ginous: where the uro-sacral region begins there two pairs of separately- ossified riblets (s.r.) are seen below the corresponding diapophyses. I find three pairs in Casuarius Bennett i * in which only two pairs of ribs are de- veloped in front {Joe. eit. s.r.); but these two sacra are very similar, and the same number of vertebra? are enclosed by the ilia in both cases. In the mooruk (Casuarius Bcnnetti), however, the first of these retains its distinct- ness as a dorsal vertebra. The arrested and somewhat retrograded Ratitse show their loss of parts and want of specialization in the caudal region. Mivart (op. eit., p. 430) gives ten as the number of caudal vertebra? in the ostrich. I find only eight in the mooruk. The same abortive condition of this part is seen * Philosophical Transactions, 188S, B., Plate LXV., fig. 8, *. r. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 25 in the Tinamous ; but in the Anatidse, as in most Carinatae, and especially in certain arboreal birds, it is a highly developed or greatly specialized* part ; for the two first moveable joints in the caudal series become pro- ccelous, and also acquire a joint-cavity. This is partly perfected in the swan, but is best seen in such birds as the horn-bills : the rest of this series is gently amphicoelous ; the two contiguous facets are joined together by fibro-cartilage. The nobler Carinatse with strong " rectrices," or tail- quills, have intereentra in this region to give greater purchase to the " depressor coccygis."")" In the cygnet (Plate V., figs. 5, 6, 11, i. c.) I find eight of these milioline cartilages : the last three of these belong to the uropygial series : the three in the middle are the largest. These figures show how strongly these unfused caudals are like those of the Ratitse: in the swans and their congeners their number is greater ; and the uropygial piece is a highly specialized region. In the adult the cervical vertebrse have a notable structure. From the third to the eighteenth inclusive, the re-entering angle between the neural arch and the retral styloid rib is largely filled in by a secondary bony lamina : thus the canal for the vertebral artery is walled in altogether in from half to two-thirds of its extent : behind, in each vertebra, the outer wall remains membranous. At the lower end of this series this plate is separated by a fenestra from that part of the wall which is formed by the open part of the riblet : thus, there is a delicate " flying buttress " running obliquely upwards and backwards from the riblet to the neural arch — a very elegant structure ; and, in this manner, the canal is often protected, notably in the Cuculine types. In the swan and its congeners the wall is completest ; and any cervical vertebra of a bird of this kind is easily recognized. All the vertebras of the swan are pneumatic, except the caudals : the cervicals, except at the two ends, are elegantly oblong, depressed more than usual, and narrowest at the beginning of the post-zygapophyses. The huge dorsals have ossified tendons on their spines and diapophyses. Altogether, this is one of the neatest groups of the Class ; but as the * See Proceedings, Koyal Society, 1888, p. 472. f See Macgillivray, British Birds, vol. 1 , p. 46, fig. 6. HOIAL HUSH ACADEMY CUIsTflXGHAAl MEMOIRS, NO. VI. [4] 26 Cunningham Memoirs. old sorts of the Chenomorphse are not all extinct, the Palamedidse still lingering' in the neotropical region, the classification of these birds is upset, and the hedge set about the group is greatly injured. The Sternum and Shoulder-girdle of the early stage in the swan (Plate L, fig. 5), along with the wings, are remarkable for their small size at present. There must be some ontological reason for this ; and putting together such facts as are patent, an approximation to the truth of the matter may be made. At present the sternum is entirely cartilaginous ; it remains so, and is very small, relatively, in the large cygnets a month old. When it does ossify it is by endostosis at first, and the three main tracts are imperfectly distinct from each other. In fowls and struthious birds the sternum ossifies earlier and by ectostosis, in very definite tracts ; though large-winged, the unwebbed Palamedida3 have a smaller sternum than the Anatidaa ; but both groups have sternum and wings large. The most generalized of the Anatidas are the geese, and the true land geese most of all. The largest of all, by far, the extinct Cnemiornis (Owen) of New Zealand,* and several existing forms, are terrestrial birds: the most generalized forms I have met with, judging from the structure of embryos at a similar stage as those of Cygnus nigricollis, are Chloephaga poliocephala of the Falklands, and Cereopsis novce-hollandice of Australia. I therefore imagine the fore-parents of the Chenomorphae to have been near akin to those of the Ratita? and those of the Gallinaceous tribes — all land birds. In that case, after the dying out of the true teeth, those primor- dial forms, neither geese, swans, nor ducks, at that time, acquired the webs on their feet, and those horny succedunea to teeth that were needful for them in their peculiar method of gaining a livelihood, namely by straining out the mud of watery places for the sake of living food. Not the less did they browse and. graze, as many of them do to this day; the most aquatic — the Fuli- gulinse and the Merganserinae — being the most completely carnivorous. The extension backwards of the sternum in birds — the "xiphoid" or * This gigantic goose was fast becoming one of the Ilatitcc (Transactions, Zoological Society, vol. ix., Plates XXXV. -XXXIX. ; and Cygnna falconeri was an Anserine swan (Transactions, Zoological Society, vol. vi., Plate XXX.). Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 27 " metasternal " region* — is, in this embryo, only one-fourth as long as the whole tract : the notch between each cartilaginous tract is further forward than the insertion of the last sternal rib. The rostral jn'ocess, in front, between the coracoid grooves, is small. The keel is rather acute- angular in front, and dies out behind, not reaching to the end of the median metasternal process. Only three-fourths of the costal edge has sternal pieces ; these died out during development in the fore part : their vertebral counterparts are seen above as the styloid ribs of the two last cervical vertebrae. Seven cinctures are complete ; the eighth nearly so ; the ninth is less than half developed ; and in two distinct tracts there was an attempt to develop eleven cinctures. This makes one figure the ancestral bird with a very long thorax. Yet in true land birds, and in the most archaic in existence, more so truly than the Ratitae, the Tinamou only finishes three cinctures (T. robustus ; T. variegatus has four), and it has the longest sternum of any bird; it is almost all metasternum, and yet has a large keel.f The coracoid grooves are separated by the small rounded "rostral process" in the Anatidse: the coracoids (cr.), therefore, do not overlap as in many birds. The falcate scapula (sc.) and the strong broad-based coracoid are quite normal, and are ossifying fast : the " clavicular process," or precoracoid root, is small in these types. The furcula (Plate IV., fr.), however, is the most instruc- tive part of the shoulder-girdle, and makes most for a kinship between these birds and the Ratitas. In the Tinamou the furcula is simple : it has no cartilaginous nuclei ossified and fused, as in most birds, notably in the Passeres, the Rapaces, and the Pelecaninae. In most of the Ratitae it has died out; but styloid remnants — simple clavicles — are seen in Cassowary s and Emus (" Shoulder-girdle and Sternum," Plate XVII., tigs. 3, 4). In the Palamedidae the furcula is composed of two massive and simple clavicles fused together as in Tinamou, and forming a U-shaped bone — quite like that which has been made out in Archaeopteryx. The furcula of the swan is quite similar, but not so massive nor so pneumatic as in Chauna chavaria. The simple parosteal clavicles of Reptiles, because of their superficial, sub- * See Lindsay : Proceedings, Zoological Society, 1885, pp. 684-716, Plates XLII.-XLV. \ Transactions, Zoological Society, vol. v., Plates XXXIX. and XLI. [4-] 28 Cunningham Memoirs. cutaneous nature, are more variable than the endo-skeletal part of the shoulder-girdle : in Chameleons they are suppressed ; and in Crocodiles only the third piece, the u interclavicle," is present (op. cit., Plate XL, figs. 4 and 8). Going back to an earlier stage, we see in the embryo duck (Anas boschas) after nine days' incubation (Plate I., fig. 5) that the scapula and coracoid are fused into one bar, which is bent upon itself at more than a right angle : it is much less so in the adult. The early position is Reptilian, and so is the con- tinuity of the two parts (see in the " Urodeles," op. cit., Plate III.). The antero-inferior bar, or " pre-coracoid," has the same arrested development as in the Rhea, Cassowary, and Emu (oj). cit., Plate XVII. ); and the mem- brane that so strongly walls-in the interfurcular space has in it, above, a small patch of nascent bone, the future " furcular ramus" (fr.). The moieties of the cartilaginous sternum are uniting, and are sending down a small keel; the costal edge has seven sternal pieces (s.r.), and there is only room for one more on the pre-costal process — not two, as in the swan. The hinder half of the metasternum is membranous at present. The Wings of the Anatidce* In the nearly ripe embryo of Cygnus nigrieollis the humerus and ulna are of the same length ; the manus is one-eighth longer (Plate IV.). The ends of the main rods are still unossified, as are the carpal segments; the general form of each element is now the same as in the adult. The proximal row of carpals has only the two normal avian pieces — the radialef (Plate III., fig. 7), and the ulnare (ue.); the latter is evidently morphologically compound, for it has two unequal lobes, one on the extensor and the other on the flexor face of the limb. The distal-carpals (d.c. 1 , (I.e. 2 , d.c. 3 ) are still distinguishable above the metacarpals. The 1st (fig. 7, d.c, d.c. 1 ) is small and ventrally displaced ; it lies below the larger lunate 2nd segment ; that piece is now fairly confluent * For bibliographical notices, see "Fowl's Wings": Philosophical Transactions (1888), pp. 385-398. f The " radiale " carries a spur in Plectropterus (Sclater : "Ibis," vol. iv., 1886, fifth series ; p. 300, fig. 3 Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 29 with the 1st metacarpal (m.c. 1 ) in front; and the 3rd distalcarpal (d.c. 3 ) behind. This latter is mainly on the ulnar side of the manus, for the "index " and its carpal are inordinately large, and have dwarfed the parts on each side; the large round head of the metacarpal of the index (m.c. 3 ) is clearly seen wedged in between the 1st metacarpal (m.c. 1 ) and the 3rd distalcarpal ((I.e. 21 ), and capped by its own large curved carpal (d.c 2 ). The small patelliform 1st distalcarpal looks forwards and downwards towards its own metacarpal (m.c. 1 ), which is only one-third the length of the next, and is not yet ossified. This segment has a large proximal "trochanter," partly formed of a band of fibro-cartilage ; this part, in some birds (e. g. Parra and Pluvianus), and notably in the Palamedidse, carries a defensive spur. The 1st metacarpal has hinged upon it a " pollex " (dg. 1 ), nearly as large as the two last phalanges of the index (dg.' 2 ); of course this latter has another — its proximal phalanx, and both are normal digits as to the number of their segments. In each of these digits the distal phalanx is the core of a claw. They are ungual phalanges ; they are already ossifying at their tip, and the others have a shaft-bone. But the proximal phalanx of the index has a flat dilatation on its hinder or ulnar edge (dg. 2 ) ; and the metacarpal of the index has, in the duck, near the top of its bony shaft on the ulnar side, a small accessory cartilage (Plate I., fig. 6, m.c. 2 ) ; the dilatation on the proximal phalanx arises as a distinct car- tilage later than the main segment. The 3rd digit has a metacarpal (m.c. 3 ) only one-third the diameter of the 2nd ; it reaches only to the bony shaft of that rod above ; but at its lower end it reaches a little further down ; its ends are still soft, and the upper is modelled on the extensor face into a distinct head ; on the flexor face it is confluent with its own distalcarpal (d.c. 2 ) This narrow bar is bowed out in the middle so as to leave an interosseous space for the muscle of that part ; below, it dilates a little, and then has articulated to it a single phalanx (dg. 3 ), where in a Reptile there would he four phalanges ; this is only one-third the size of the second phalanx of the index ; it is not yet ossified. Altogether, the index has overshadowed and starved the 3rd or hind-finger. As a rule, in old birds, this is the hindmost digit. There is, however, a very small remnant of a 4th metacarpal on the flexor side of the 3rd near its top (Plate III., fig. 7 a , m.c. 4 ); the accessory cartilage attached to 30 Cunningham Memoirs. the 2nd metacarpal is on the extensor side. I shall refer to these parts again in describing the Alcidre. The wings, like the sternum of the cygnet (Plate V., fig. 7), grow slowly ; all there is to remark upon, as yet, is the extension of the bony shaft and the ossification of the 1st metacarpal (m.c. 1 ) In old swans the relative, as well as the really great size of the wings, is greatly altered from that of the nearly ripe embryo ; this is well seen by comparing the fore and hind limbs. In. that early stage the ulna was 17 millims long, and the tarso-tibia 27 millims. In the old white swan the ulna is 270 millims long, and the tarso- tibia 203 millims, or only four-fifths. The humerus is now 287—5 millims long, or 17 - 5 millims longer than the ulna. The manus is now 240 millims, or 30 millims shorter than the ulna. But in the embryo the manus, as I have shown, was one-eighth longer than the humerus and ulna, which were both of the same length. I found, in the old white swan, the distalphalanx of the pollex 10 millims long, and that of the index 14 millims ; they were, in both, straight and sharp-pointed — they had lost their claw-form. Thus the specialization in those birds is seen in the humerus becoming larger than the ulna, instead of being the same size, while the manus. which was one-eighth longer than both those segments, is now 30 millims shorter than the ulna, and 47*5 shorter than the humerus. The teleological bearing of this is, that the wings have largely changed their size as compared to the legs ; they were only half the size — they are now much larger. The overgrowth of the humerus, as compared with the ulna, has reference to the quiet, buoyant, continued power of flight in these birds ; the ulna has gained more room for the secondaries, whilst the space for the primaries, although larger, is relatively less. The humerus is the only pneumatic bone in the limbs of the Auatidae ; in Chauna chavaria only the ungual phalanges retain the marrow. All these things suggest that the Anatidee were, in their remote parents, stout strong-legged land birds, with short wings, a small sternum, and with no special fitness for an aquatic life, beyond that of wading in shallow waters.* * Wolf's excellent figure of Chauna nigricollis (Proe. Zool. Soc, 1864, Plate XLL, p. 74) shows that archaic hen-faced " Cheuomorph " in the very attitude anil act of wading ; its resemblance Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 31 If I were to go no further down, and no further afield, than this exami- nation of the large embryo of the nestling and the old swan, half the interest of the matter would be still untouched. I have still to describe the early stages of the wing in the common cluck, and the rare conditions of this part seen on the embryo of Chloephaga, and in the adult of one of the Palainedidas. Stage 1. — Wing of Embryo Duck (Anas boschas), 9th Day (less advanced). The paddle-shaped fore-limb at this stage differs but little from the hind-limb (Plate L, figs. 1, 2). There is a tendency to lobulation of the spatulate end of the limb ; and this is manifestly due to the growth, along certain lines, of radiating thickenings of the tissue which are fast growing into pointed hyaline cartilages. There are, already visible, three such rays in the fore-limb, and four in the hind-limb. There is, indeed, an arrest, almost suppression, of two of the normal rays in the wing, and of one in the leg. If these limbs be considered to be the modifications of what we see everywhere in Reptiles, it is evident that some of the rays have been smothered in their growth — probably, in some degree, by the great start that the developed parts have got. Potentially, the seeds, so to speak, of the missing rays were duly sown ; for in the case of the wing, one of the two lost rays makes a little attempt at growth, and the one missing ray in the leg does the same; but the developed parts have " sucked their verdure out." Already, the main regions of the limb are differentiated ; and the chief segments have become hyaline cartilage ; the more inconspicuous elements and distal parts of the skeleton of the wing are still composed of embryonic cartilage or "indifferent tissue"; as to the larger rods, I have not overdrawn their distinctness. Whilst the muscles are still in formation, the harder tracts of tissue for their origin and insertion are already prepared. This is well seen in the humerus (Plate L, fig. 1, outside view of to the coots (Rallidse), in respect of its huge toes, which are really those of a swan without the web, made the old Ornithologists (Vigors, Cuvier, &c.) put it with the Eallida; and also along with Parra and Megapodius. 32 Cunningham Memoirs. right wing) and in the cubitus (r.,u. ). Distinct from these parts, but only semi- distinct from each other, are the parts that form the carpus ; on the ulnar side, a large wedge of soft cartilage (ue.) is seen, with its sharp edge above ; and on the radial side there is a thick mass (re.) notched both by the ulna (u.) and the radius (;■.) Beyond these, at the mid line, another large mass is seen (d.c. 2 ), and on its ulnar side a much smaller half-distinct nucleus (d.e. 3 ); these both become the second and third distalcarpals. Growing forward from them, quite cartilaginous rods are seen ; these, which are more and more soft towards the end, are distinctly segmented a little beyond their middle. Thus we have the large second and the small third metacarpals (m.c. 2 , m.c. 3 ), with their sprouting phalanges (dg.", dg. 3 ) forming the second and third digits. The first distal carpal is not evident in this stage (I shall show it in the next) ; but the first metacarpal with its sprouting digit, the pollex, is already clearly seen. The small rough model of a bird's-wing skeleton is to be clearly seen in this weak rudiment up to the wrist (carpus) ; but the three rays are the diverging, sprawling fingers of a Reptile. Stage 2. — Embryo of Duck after Nine Dags' 1 Incubation [more advanced). In a further growth of the wing (Plate I., fig. 3, inside view of right wing) the sprawling of the fingers is not so great, and the softer parts are more clearly outlined ; they are now almost hyaline cartilage. The pre- paration here figured was a stronger and larger embryo than Stage 1, but the period of incubation was the same. The elbow is now definitely bent ; and, the whole structure becoming avian, the bird is becoming more and more, the reptile less and less. What may be called the necessary and normal parts of the skeleton of the wing are all now present. These are the parts chosen beforehand by the elective affinities of the morphological force to form this — the strangest type of limb. The human arm and hand are simple and primitive, and nearly normal in comparison with this "freak," which is specialized for flying. We have only to look at the large masses of hardening cartilage that form the avian radiale and ulnare {re., ue.) to see that they are only semi- Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 33 differentiated lumps of tissue. They, as can be proved by their behaviour in certain birds, represent two or sometimes three carpals of more normal fore-limbs ; the ulnare is in two lobes even now. The three distalcarpals (fig. 3, d.c. 1 , d.c. 2 , d.c. 1 ) can all now be seen on the inner or flexor side of the wing; the first (d.c. 1 ) is a small hemispherical nucleus inside the junction of the second metacarpal witli it distal carpal (m.c. 2 , d.c. 2 ). The latter is a large lunate mass, curving round the head of its own metacarpal ; it thrusts the third distalcarpal (d.c. 3 ) forward. This is an oval piece, larger than the ventrally displaced first, but oidy one-fourth the size of the second. The pollex (dg. 1 ) shows its distal phalanx as a conical mass of soft tissue on the end of the proximal phalanx. The index (dg. ") and the third digit (dg. 3 ) have only their proximal phalanges in the state of hyaline cartilage. The third digit is drawing nearer to the second, which all along has been twice its bulk, but not much longer. Stage 3. — Embryo of Duck, after Twelve Days' Incubation. During the next three days the transformation of the tridigitate paw (or paddle) into the wing has been very rapid, and almost complete as to form. The main bones (Plate I., fig. 6, r., u.) have acquired an ectosteal sheath, and all the elements are well solidified as hyaline cartilage : more- over, fusion of some of them has already taken place, and new parts have become differentiated. The various joints, or condyloid faces of the segments, are now fairly modelled by the process of mutual adaptive growth of contiguous parts : these are very perfect, notwithstanding the limited mobility of this metamorphosed member. The proximal carpals, the radiale and ulnare (Plate I., figs. 6, 7, re., ue.), are now very perfectly pre- formed in cartilage : the radiale is a massive lunate wedge ; the ulnare is a bilobate segment, with its " elbow" behind, and its longer oval lobe on the inside : it overlaps both the ulna and the third distalcarpal (u., d.c. 3 ). The large projecting second distalcarpal (d.c. 2 ) is now confluent with the first metacarpal (m.c. 1 ) in front, and the third distalcarpal (d.c. 3 ) KOYAL IEISH ACADEMY CUNNINGHAM MEMOIRS, NO. VI. L^J 34 Cunningham Memoirs. behind : thus, its own huge metacarpal (m.b. % ) has its head inclosed in a thick cap of cartilage. Its outline, however, is quite clear ; so also is that of the third metacarpal (m.c. 3 ) ; but its distalcarpal (d.c. 3 ) is fused above. The first distalcarpal (fig. 7, d.c. 1 ) is now a clear bud of cartilage, flattened on its adherent face, and placed inside the head of the second metacarpal. The first metacarpal (m.c. 1 ) runs parallel with the unossified head of the second ; it is half the size of that head, and has a large flat " trochanter" on its proximal end ; it then narrows and forms a condyle for the pollex (dff. 1 ). That digit, with its metacarpal, is half the length of the whole index, meta- carpal, and phalanges, together ; but its proximal phalanx is as long, but not as stout, as that of the second; its distal phalanx (so-called ungual) is almost the size of that of the index, which is nearly as large as the second or middle joint of the digit. In the pollex, especially, it is seen that the distal phalanges are not ungual as yet, but are lobate and flat at their free end, and represent not the claw- joint of a Reptile, but the last piece in the soft-ended finger of an amphibian. At present, the terminal pieces of all the three digits are alike ; but that on the third (dg. 3 ) represents merely the proximal stump of a Lizard's third fore-toe, which has four phalanges in it. The first and second digits in this wing are normal ; the third is aborted. But a much more abortively- developed digit is seen behind the third : this {in.c. i ) is a rudiment (or remnant) of the fourth metacarpal of a Lizard's fore-foot : it is on the flexor side of the hind margin of the third, close to its rounded and distinct top. This remnant is common in the Carinatse : in Opisthocomus this digit re-appears as a proximal phalanx ; it is, in that bird, a distal, not a proximal, remnant. An accessory cartilage is now seen as a thin flap on the ulnar side of the proximal phalanx of the second digit (dg.~): the second and third meta- carpals have acquired a considerable bony (ectosteal) tract. The distal phalanx of the second digit is not so well developed on the right (fig. 6«) as on the left side : bilateral asymmetry is not uncommon in the wings of birds. Me. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 35 Stage 4.— fflmbryo of Duck, after Fourteen Days' Incubation. After two days more there are two new ectosteal tracts — those of the proximal joint of the pollex and of the index (Plate I., fig. 8, dg. 1 , dg. 2 ) ; the other parts are similar, but larger: the first distal carpal (d;c l ) is growing towards its own metacarpal (m.c. 1 ). The difference in the size of the two lobes of the ulnare is now well seen (figs. 8, 9, tie.). The distal phalanges of the pollex and index (dg. 1 , dg. 2 ) are becoming curved as ungual joints. Stage 5. — Embryo of Duck, after Eighteen Days' Incubation. In this stage (Plate II., figs. 4—6) there are several points to be noticed. The second phalanx of the index (dg. 2 ) is ossifying; and the large curved distal joints of both that and the first digit (dg. 1 , dg. 2 ) have a terminal horny sheath. In the more enlarged figures (figs. 5, 6) there are some important parts displayed more plainly : the accessory tract of the second metacarpal (m.c. 2 ), which is very small in the Anatidse, and very large in the fowl tribe, can be seen as a narrow tract of cartilage growing forwards from the ulnar side of the great distalcarpal (d.c. 2 ). The first distalcarpal (fig. 5, d.c. 1 ) is now a thick band of cartilage which has grown across the head of the second metacarpal, and has applied itself to its own metacarpal (m.c. 1 ). In the same view the fourth metacarpal (m.c. i ) is plainly seen as a small pyriform nucleus of hyaline cartilage. On the outer or extensor face (fig. 6) the peculiar free end of the outside of the third metacarpal is also well seen. Stage 6. — Embryo of Duck, just Ripe. In this stage I have shown the proximal end of the manus (Plate II., figs. 8, 9) : it differs but little from the last ; but the fourth metacarpal (m.c}) is becoming confluent with the top of the third (m.c. 3 ) Stage 7. — Duckling Three Days Old. The same parts are shown in this stage (Plate II., figs. 10, 11): the fourth metacarpal (m.c. 4 ) is now confluent with the third (m.c. 3 ) : the accessory [5*] 36 Cunningham Memoirs. part to the second metacarpal (m.c. 2 ) is now a thin point of cartilage embracing the large bar on its ulnar edge above. Stage 8. — Old Duck (Anas boschas). As compared with that of the swan, the wing of the mallard — and also that of the tame duck and of the sub-family Anatidae generally — is relatively, as well as really, short : they are heavy birds to be carried with such wings as they possess. In these smaller forms the cubitus is considerably the smallest of the three divisions of the wing-skeleton, and the manusthe longest ; they beat their wings rapidly in flight, unlike the " longipennes," birds with very long humeri. During the growth of the duckling, the carpals all acquire an endosteal centre ; the two proximal segments remain free ; the three distal become fused with the metacarpals, and these with each other ; the second and third at both ends. The ungual phalanges of the pollex and index remain in the adult as sharp and straight pieces: the latter is the longer; and thus, besides the free synovial articulations of the two proximal carpals with the cubital bones above, and the compound manus below, the pollex has two, the index three, and the third digit one, moveable articulation permanent — just as much as is necessary in this transformed arm and hand, with its marvellous investment and its new function. The Hip-girdle of Anas boschas. In this species I am able to give three stages earlier than that of the nearly ripe embryo of the swan (Plates IV. and V.); and these show what transformation an average reptilian pelvis undergoes in the bird, correla- tively with that of the shoulder-girdle and wing. The changes are very great in these parts, but not so great as in those. Morphologically, the steps or stages of this metamorphic process may be said to be four in number: we have — 1, the general Reptilian; 2, the Ornithoscelidau ; 3, the Struthious ; and 4, the normal Carinate stage. These stages are not so clearly defined in the hind-limbs : they are very marked in the moieties of the hip-girdle. Me. W. K. Pakker. — Morphology of the Duck and the Auk Tribes. 37 Stage 1. — Pelvis of Embryo Duck, Nine Days' Incubation {less advanced). This first, or Reptilian, stage of the hip-plate (Plate II., fig. 1) is shown in relation to the hinder-part of the vertebral chain, which is rapidly form- ing round the notochord (nc), and over the myelon. This stage is well illustrated in Miss A. Johnson's valuable Paper on the development of these parts in the Chick.* The vertebral formula of the adult duck is as follows : — C. 16; D. 5; D. S. 3; L. S. 3 ; S. 3 ; U. S. 7 ; Cd. 8 + 5 = 13 : Total, 50. Of these the last two cervicals have free ribs : and also the first three sacrals, or dorso-sacrals ; and there are rib-bars on two or three — originally on five — of the urosacrals. Now, the three true sacrals are exactly over and between the acetabula. In this first stage, therefore (Plate II., fig. 1), there are four in front of these covered by the anterior lobe of the ilium (pre-tlium), and three uro- sacrals by the posterior lobe or post-ilium — ten altogether, instead of sixteen as in the adult. At a still earlier stage there would be fewer, f in which stage the crest of the ilium is scarcely more dilated than the " supra-scapula," as in some Lizards (see, in Stellio, Shoulder-girdle and Sternum, Plate XL, fig. 1, s.sc). It has, moreover, to be kept in mind that hosts of small and nobler birds have only ten vertebras embraced by the ilia, although eleven is the most common number : the duck is a medium, the swan an extreme, case. In Ignanodon bernissartensis there are ten vertebras fairly between the ilia, as in my first stage in the embryo duck. J This first stage, however, has the hip-plate, as a whole, not in an Ornithoscelidan, but in a general Reptilian condition. It is instructive to see how the pre-ilium at present preponderates over the post-ilium ; for it is the great development of the latter region that makes the bird's pelvis so remarkable; a still more remarkable fact being the adumbration, by the unwieldy Iguanodon, of the * Studies, Morph. Lab., Camb., vol. ii., Plate IV., figs. 3-6. f See A. Johnson, op. cit., Plate IV., figs. 3, 4. X Dollo, Bull. Mus. Koy. Hist. Nat. Belg., t. ii., Plate V. 38 Cunningham Memoirs. hip and legs of such small, light, airy forms as the nobler types of birds. Of the vertebrae that are built in between the hip-plates the last seven are, properly speaking, caudal ; then follow, as a rule in this bird, thirteen more, the last five forming the uropygial piece. But I have seen as many as ten segments in that terminal region (Plate II., fig. 12); that would give twenty-five for the post-sacral or caudal series.* These, were they elongated as in the tail of Archseopteryx, would have formed another " Saururous" type. It is easy to imagine such a hind-spine as the one depicted (Plate II., fig. 1) as rapidly developing into the tail of a Saururous bird, instead of contracting itself into the stunted and largely fused uro-sacral and caudal series of a duck, or of any normal Carinate bird. Palaeontology is extremely tantalizing at this point. Geologically not so much older than Marsh's toothed birds, the Archaeopteryx has no claim of fatherhood upon them : the gulf is not so great as between the Iguanodon and the Humming Bird ; it is, however, unbridgeable, notwith- standing. One more remark. In cartilaginous fishes — above all, in the Ray family — the neck becomes a quasi-s&cram ; for the shoulder-girdle is fixed like the hips of higher forms : the fore limbs dominate the hind limbs, as they are the chief paired organs of progression. The flying bird would seem to be relapsing in this respect, the fore limbs being its main organs of progression : but the bird is merely a land animal modified ; hence its hind limbs are well developed also. In the formation of these noble feathered forms it is instructive to see the part played by the notochord, and the rapid manner in which it becomes contracted and obscured, and then transformed into a mere ligament ; in my first stage (Plate II., fig. 1), had it gone on growing and developing t'he vertebral segments on and around it, this bird must have soon become one of Professor Huxley's " Saururae " ; it was, however, ordained to become one of his Carinatce. By careful dissection of early embryos, Miss B. Lindsayf was able to * See Proceedings, Zoological Society, 1863, p. 1-8. f Proceedings, Zoological Society, 1885, p. 704. Mr. W. H. Parker. — Morphology of the Duck and the Auk Tribes. 39 show that the shoulder-girdle of the bird arises as three {apparently") separate tracts of embryonic cartilage ; that is, however, prior to the formation of true or hyaline cartilage, for this tissue runs freely from the scapular to the coracoid region, thus forming one curved bar. The jDre-coracoid tract only partially ossifies, and that in two ways, namely, by a rudiment grow- ing directly from the coracoid, and often by one or two distinct cartilaginous tracts; the rest of the anteroinferior bar grows into a mere "parostosis" — the simple clavicle. But there is no parostosis in the hip-girdle : the whole structure answers to such a shoulder-girdle as that of the Amphibia, Chelonia, and of Struthio camelus. (See " Shoulder-girdle and Sternum, Plates III. — VIII. ; Plate XII. ; and Plate XVII., figs. 5, 6.) This subject is rendered difficult through the peculiar development of the hip-plate in the Dinosaurs. (See Dollo, op. cit., Plates III. and V. See especially Plate III., fig. 2. In Iguanodon bernissartensis the pubis sends forwards a large broad prepubic bar, called by Dollo "pubis"; whilst the already rotated pubis — the long, narrow hind-part — he calls "post-pubis"; the term pre-pubis is the better for the fore-part. The ischium also, where it binds upon the post-pubis, sends down upon that bar a shorter anterior and a longer posterior process, to enclose the proper obturator foramen. Now, if these parts and pro cesses be compared with those seen in the shoulder-girdle of certain Lizards, e.g. Iguana tubcrculata {op. cit., Plate IX., figs. 1, 2), and if the unossified free edge is supposed to be absent, then we are shown how that these plates may send out secondary bars : in the Iguana there is one large bar from the scapula, and two in front of the coracoid proper. So I interpret the pro- cesses on the pubis and ischium of the Dinosaurs. In birds the pre-pubis is often suppressed, but it has a considerable development in the Ratitse, Tinamidas, Gallinacese, and the Ground Cuckoos (e.g. Geococcygx, &c). In Dollo's Plate III. the pelvis of a young fowl is figured : in it the small pre- pubis is shown to be ossified by the ilium, and not by the pubis. In other Carinatse, as far as I have seen, the same thing takes place ; a good instance at hand being the pelvis of a newly-hatched quail (Coturnix dactylisonans). In it the pubic ossification reaches the base of the finger-shaped pre-pubic lobe ; afterwards the suture between that bone and the ilium runs directly inwards, as in Dollo's figure; and thus the spur receives its bony deposit 40 Cunningham Memoirs. from the ilium. In an earlier stage of Phasianns versicolor the spur is endosteally ossified, and is in front of the suture between the ilium and pubis.* I feel certain that Professor H. G. Seeley, F.R.S.,t has unnecessarily raised a difficulty and a doubt about the pubis of the Crocodile ; and that the view taken by Ratlike, Hoffman (in his later writings), Huxley, Hulke, and myself, is quite right ; our interpretation of this part will be found to be true. In perfect harmony with these received views are the figures given in Miss A. Johnson's Paper {op. cit., Plate IV., figs. 3—6) ; and my own first stage in the duckling, fig. 1 (Plate II.), as compared with figs. 2 and 3, suggest the same identification, exactly. J In my figure of the first and second stages in the embryo duck I have shown a considerable amount of distinction between the three main parts. This is seen still better in a chick than in these embryos. In it, espe- cially when the pubis and ischium have just rotated, the three parts are semi-segmented from one another ; a deepish chink is formed, as although a piece of cardboard were nearly cut through with a knife ; the chinks are filled with connective tissue cells : at the first adjustment with a high power these seem to pass through. A deeper adjustment shows an extremely thin tract of cartilage on the inner face of the object: anyhow, this is very noteworthy, showing that the root and foundation of the limb is formed of three rays — parts that are homologous with those that form the fore-limb. * In a letter from one of the best of living paloeontologists, J. "W. Hulke, Esq., F.K.S., received December 15th, 1887, in answer to one from me, he says : — " In your fig. 3 of a bird's pelvis you represent the pre-pubic spur as wholly iliac. The corresponding spur in Apteryx, and in alien ainericana certainly contains a pubic element ; for its suture, in immature specimens, runs through the spur, which has thus an iliac and a pubic component." Bearing thereon, Mivart's figure of the pelvis of a young Ostrich (Trans., Zoological Society, vol. viii., p. 437, fig. 74) shows this; but unfortunately the cartilaginous spur was not pre- served nor figured. Yet, if that figure be compared with one of the adult (p. 433, fig. 71), it will be evident that the ilium and pubis meet in the root of the process. f Proceedings, Royal Society, 1887, pp. 235-242. J The embryos of the Crocodile referred to by Professor Seeley as coming from me {op. cit., p. 24) were unfortunately too old for such researches. Two years afterwards I recovered the early stages which I had wished to put into Professor Seeley's hands. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 41 The flabelliform ilium (il.) is parallel with the spine in its dilated part ; but its axis is at a right angle with it : such an ideal line would pass directly between the two lesser bars, the pubis and the ischium. The former of these has now very nearly the position which is permanent in the crocodile.* In this early stage the pubis and ischium diverge at less than a right angle : they are broad and flattish tracts composed of hyaline cartilage in their upper three-fourths, but are still in a state of " indifferent tissue " below : the angles of the ilium are in the same stage, as yet. The deep setting of the femur has stopped the growth of the cartilage, so as to show, already, a large hole in the fundus of the acetabulum. Stage 2. — Pelvis of Embryo Duck of Nine Days' 1 Incubation {more advanced). In this stage the hip-girdle embraces fifteen of the general sacral series of vertebrae ; only the last appears like a pre-caudal. In a general way this condition is very Dinosaurian, for the pubis (pb.) and ischium (isc.) are rotated backwards, but are still at a great distance from the caudal spine, and are relatively very large. Afterwards (fig. 3) the pubis becomes much longer than the ischium ; now it is but a little longer : in Dinosauria, as a rule, the ischium is much longer than the pubis. There is no pre-pubic spur ; and, at present, besides the absence of any bony deposit, the distal parts of all the three bars are still composed of indifferent tissue. They are all free from each other behind, so that there are no "fenestra?," but a series of long notches, a sacro-iliac, an ilio-ischiatic, and an obturator notch. A comparison of this, of the next stage, and of that of the almost ripe embryo of the swan, with those of the adult Ratitse and of the Gallo- struthious Tinamous, is very instructive as helping to throw light upon the forms that birds assumed in the olden times. We have, however, to be very careful to sift out the specialization of * Huxley, Proceedings, Geological Society, 1869, p. 27, fig. 3; Dollo, op. cit., Plate III., fig. 1 c. ROYAL IRISH ACADEMY CUNNINGHAM MEMOIRS, NO. VI. [6] 42 Cunningham Memoirs. arrested types ; for, as a rule, existing archaic forms are in some respects more modified than the culminating types ; and we must recollect that they have as long a list of ancestors, and have been as long in existence in the loins of those ancestors, as the newest and noblest forms. That the Ratitas represent several distinct families of birds there can be no doubt ; nor can it be doubted that the Tinamous are less degraded archaic forms closely allied to them. I have already shown how near the embryo swan's pelvis comes to that of the African ostrich. In this second stage of the duck the hip-plate wants but little further growth and modification to make it into one like that of the cassowary.* In a few birds [e.g. the Buceridas and Pieidse) the pubis, in the adult, becomes fused with the ischium, below, as the post-ilium does normally, above. In the cassowary all these bars are fused together in the cartilaginous condi- tion: a little further chondrification would have done this in this second stage of the duckling. Further, in the chick, at this stage, the pelvic plate is precisely like that which is seen in the adult Tinamou. All these things are to be noticed and kept in mind.f Behind the sixteen vertebras that are, all but one, enclosed between the hip-plates there are thirteen segments, forming the caudal series : these are terminated by the blunt end of the notochord (no.). The rapidity of this pre-natal transformation is extremely great — as great as anything to be seen in the flowering of plants. The first and second stages had both been incubated nine days ; but the second had got, in some way or other, a fair day's start, as to growth, of the first ; and, in this short time, the whole difference between a general Reptilian and a Dino- saurian pelvis had been effected. Stage 3. — Embryo of Duck after Tioclvc Days' Incubation. Here (Plate II., fig. 3), we see how rapidly the Carinate bird's pelvis passes into its typical condition : the general size has greatly increased ; * Philosophical Transactions, 1888, B., Plate LXV., figs. 8-10. f See Mivart, Transactions, Zoological Society, vol. viii., pp. 385-451 ; and vol. x., pp. 1-52 ; and " Gallinaceous Birds and Tinamous" : Transactions, Zoological Society, vol. v., pp. 149-241, Plates XXX1Y-XLII. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 43 the cartilage is completed, and in parts is being transformed into bone. The pre-ilium (pr.i.) is now broader and relatively shorter; and the post- ilium (pt.i.) is well ossified, and is very broad behind the sacro-ischiatic fenestra (s.i.fX That space is not yet enclosed by fusion of the post-ilium with the ischium (isc.), but lies upon its hinder half, or nearly half; its broad, lobate hind-part lies upon the long, curved, and spatulate hind-part of the pubis {pi.). As in the African ostrich and the swan, the pubis of the duck and its congeners becomes greatly unlike that of a Dinosaur : instead of being shorter it is one- third longer than the ischium. Bony deposit is seen both in the pre-ilium and the post-ilium, fore and aft of the acetabulum (ac. ), and at the lower border : the bony shafts of the pubis and ischium are rapidly elongating ; that of the former remains unossified at its dilated end in the adult, and then the pubis is twice as long as the ischium : it is somewhat shorter in Stage 1, a little longer in Stage 2, and one- third longer in Stage 3. These pubic bars differ little in the ostrich and the duck tribe, except that in the latter they do not coalesce, but remain as distinct elastic supports to the oviduct in oviposition. The Hind-limbs* of Anas boschas. Stages 1 and 2. — Embryo of Duck, Nine Days' Incubation (less, and more matured). My earliest stage (Plate I. , fig. 2) is very nearly the equivalent of that given by Miss A. Johnson in the chick (op. cit. Plate V. fig. 9). It is remarkably like the fore limb (fig. 1) of the same stage, already described; but it has four developed digits, and the rudiment of a fifth. The main rods are composed of hyaline cartilage, sharply differentiated from the surrounding tissue: the distal parts are still "indifferent" and soft. The rapidity of growth of these embryos is well illustrated by a comparison of the humerus with the femur (fig. 1, h; fig. 2,/.); for they have already acquired their peculiar form. In the next segment, the leg, * The reader is referred to the following Papers out of many on the subject. They will be sufficient to show that it has taken a quarter of a century to find out what are the real elements [6*] 44: Cunningham Memoirs. the two limbs are now sharply in contrast ; for the fibula (fig. 2, fb.) is only half as thick as the radius (fig. 1, r.) ; moreover, the inner (or pre-axial) rod in the wing is the shorter and slenderer piece : in the leg it is the outer (or post-axial), namely, the fibula (fig. 2, fb.). This difference and the oppo- site direction in which the limb is bent — the elbow backwards, and the knee forwards — show what great changes the ancestral amphibian limb has under- gone.* The pala3ontologist will see at once how carefully the bird walks in the steps of the Dinosaurs. My figure of the skeleton of the leg (fig. 2) can be simply superimposed upon his. There is part for part, digit for digit : the nearly useless fibula, dominated by the one necessary segment of the leg proper, the tibia, is already slender and short ; it is only one-third the thick- ness of the tibia, and its terminal part runs short of the ankle-joint: it is only five-sixths of its proper length ; whilst the distal part of the tibia is dilated so as almost to reach the fibular, or outer, edge of the limb. What seems like an " elbow " at the top of the tibia is, in reality, the rudiment of the large, folded cnemial crest: this part is developed like a "trochanter," and always has its own epiphysis in a young bird. In many birds there is no other epiphysis whatever. of this remarkably modified limb — a limb curiously transformed from what is typical, and, what ■was still more unexpected, its almost perfect conformity with that of the Dinosaurs. W. K. P.: "Osteology of Balceniceps rex": Transactions, Zoological Society, vol. iv., 1851-61, p. 343. Gegenbaur, C. : " Vergleichend-anatomische Benierkungen iiber das Fussskelet der Yogel" : Archiv. fiirAnat. und Phys. Jalirgang, 1863: pp. 450-472. Huxley, T. H. : " Dinosauria and Birds." — Proceedings, Geological Society, 1869, pp. 12-31. Morse, E. S. : "On the Identity of the Process of the Astragalus with the Intermedium." — Anniversary Memoirs, Post. Soc. Nat. Hist,, 1880, Plate I., pp. 1-10. Baur, G. : "Her Tarsus der Yogel und Dinosaurier."— Morph. Jahrbuch, Bd. VIII. (Taf. 19, 20, pp. 417-456. Johnson, A. : " On the Development of the Pelvic Girdle and Skeleton of the Hind-limb in the Chick."— Stud. Morphl. Lab. Camb., vol. ii., 1886, Plates IV., V., pp. 13-27. W. K. P. : Proe. Hoy. Soc. 1887, pp. 57-58 : N.B.— On p. 58, line 11 from the bottom, for " always," read " never." * This is not well shown in the somewhat diagrammatic figures here given, in which the inner or anterior side is figured behind and below. Me. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 45 But in all birds, whilst growing, there is what seems to be a large distal epiphysis to the tibia.* The absence of any apparent tarsal bone in existing birds has been so long taken as a fact about which there is no question, that, even now, some of my fellow-labourers are still sternly opposed to such a great primary complexity in this part, as for some years past I have been able to demon- strate. Both in Dr. G. Baur's figures of sectionsf and in the figure, just referred to, of Miss A. Johnson there is no sign of a cartilaginous intermedium, such as I have figured in my first and second stages (Plate I., figs. 2 and 4, /.). Happily, however, they both show the distinctness of the tibiale and fibulare, and also the proximal rudiment of the fifth metatarsal. My preparations of these parts in the duck's embryo were made in the early part of 1887: those of the chick in a stage equal to that of Miss Johnson's fig. 9 were made a year before. After lying in oil of cloves for some months all these preparations were mounted in Canada balsam : they show still more clearly now what I discovered then. In Dr. Baur's method — by sections — nothing would be easier than to miss the thin intermedium ; for it lies above and con- siderably in front o/the tibiale and fibulare. Both under a lower and a higher power it can be clearly seen as a thin pyriform cartilage, with its broad end below, and lying in front of the fibrous lower end of the fibula (fb.). The tibia (fig. 4, t.) soon gets behind it, as it becomes very much dilated below. When the microscope is adjusted so as to show the tibia, fibula, tibiale, and fibulare (Miss A. Johnson's fig. 9 shows this well), then there is no intermedium to be seen. The gentlest elevation of the object glass, how- ever, makes all these jjarts cloudy. And now the intermedium comes clearly into view : it may easily be mistaken, even then, for a part of the dilated base of the tibia. Now, as this distinct tract of cartilage becomes ossified by ectostosis at about the middle of incubation ; and, as the tibiale and * My figures of this pseudo-epiphysis in an emu chick, six weeks old, were made in the year 1842. After much meditation upon this anomalous structure, I, at length, timidly suggested that this part was, in reality, the astragalus, and not an epiphysis, f " Der Tarsus der Vogel und Dinosaurier," Plate XX. ■JL6 Cunningham Memoirs, fibulare are still mere endosteal nuclei in the centres of the cartilage in cygnets one month old, how can the ascending process be a mere outgrowth, or peri- osteal addition, to either the tibiale or fibulare, or both parts, which have no such periosteal structure possible until the bird is fairly adult? Also, to which of these tarsals does it belong? and why do they develop this tibial clamp, seeing that they must so soon be fused with the main bone ? Another question arises, namely, is it a tarsal bone ? — was it not a third shaft-lone in the leg of the old ancestors of the reptiles and birds ? As cartilage, it arises earlier than the tibiale and fibulare — as bone, much earlier ; and its mode of ossification is not that of any. tarsal (or carpal) that I know of.* At present the fibulare (fie.) is a round nucleus of soft cartilage, only one-third as large as the transversely-expanded tibiale (te.). This is well shown in the chick in Baur's sections, and in Miss A. Johnson's dis- section. The distal part of the tarsus is in a very undifferentiated condition. Only one nucleus can be traced (d.t.): this appears over the middle of the perfect metatarsals (m. t. 3 ) ; it then grows right and left as a horizontal wedge. The most evident subdivision of this piece is to be seen in nestling sparrows (Passer domesticus) when the bony deposit is in these lobes. Belonging to the 2nd, 3rd, and 4th metacarpal, this piece corresponds with the inner part of the "cuboid," and the outer and middle "cuneiform" bones of one foot. But in our foot there is an element called the " scaphoid " : it is wedged in between the astragalus (tibiale) and the three cuneiform bones. This element is more or less developed, generally, in embryo birds : in fowls, struthious birds, and Tinamous, and in arboreal birds generally, it becomes ossified, and serves as a sesamoid to the plantar tendons. Morse (op. cif., Plate I., fig. 8) figures it in the embryo of the Eider duck, and puts a ? to it. It is not quite distinct even in my second stage ; but I shall describe it in * I greatly rejoice over tlie -work of rny young friends, whose views are criticized above ; but I have spent years over this kind of work, where they have spent weeks. There is such a thing as " personal equation " to be made account of in scientific research ; and there is such a state of mind in some workers, that they believe in no eyes but their own. Me. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 47 the 4th. This nucleus is found in the large interarticular plate, which is seen between the proximal and distaltarsal masses in the inner {tibial) side of the joint, and becomes thrust backwards when the ankle is complete: the scaphoid is a centrale. This part was first seen by me to have this interpretation early in 1886; and soon afterwards (independently) by my son, T. J. Parker, in the embryo of the Aptcryx, It is very large in the adult Buceros ruficollis, and is permanently anchored to the large inter- articular fibro-cartilage. Even in the adult, where it serves a sesamoidal function, it is permanently fixed between the astragalus and the part which answers to the middle cuneiform bone.* These two stages (Plate I., figs. 3, 4) show how the fore-paw of a reptilian form begins to take on the ornithic characters. In its utmost specialization (the whole limb becoming single down to the toes, and then supported on four, three, or even two of these), the leg and the shank being, as in the flamingo and stilt plover, extremely elongated ; and yet, so exquisitely hinged and upheld, that one limb alone is sufficient for the firm support of the whole body. This last result of the avian transforma- tion cannot be too much admired. Nor are the varieties of the avian leg and foot less excellent in this class, each member of which is a cunning gymnast. Here in the duck we have the beginning of that modification of the hind limb which has attained its utmost perfection in the loon (Colymbus). Already, in stage 1, the hallux, or 1st digit, is being carried away from the tarsus ; in stage 2, its arrested metatarsal (mi. 1 ) is attached to the middle of the next (m.t. 2 ); still, even in this stage, the toes are sprawling, and their metatarsals are free and diverging. In stage 1 the digits (fig. 2, dg. 1 " 4 ) are soft, and their phalangeal segments very un- defined ; in stage 2 (fig. 4) these are hardening and sub-dividing : the remnant of the 5th {m.t. 5 ) can now be seen as a globular mass of softish cartilage. Had it been developed with three or four phalanges at its end, the reptilian foot would have been complete. Even in the second stage the toes are amphibian as yet ; and the general * See T. J. Parker, Proceedings, Eoyal Society, 1888, p. 487; and W. K. Parker, ibid., 1887, p. 58. 48 Cunningham Memoirs. web, which is retained for all but the 1st digit, is simply the common expansion of the paddle, or hind oar, of a low, swimming creature. Stage 3. — Embryo of Duck, after Twelve Days' Incubation. In three days' growth the sprawling reptilian foot becomes almost typi- cally ornithic : it is typically ornithoscelidan. What concerns us most now is the further and further marking of the elements of the ankle-joint and instep, tarsus and metatarsus. The bony shaft of the tibia (fig. 10, t.) is creeping along the cartilaginous rod ; the fibula, also, and the femur are ossifying. In the figure, the parts that form the ankle-joint are shown in a dislocated state for illustrative purposes. As yet the tibia, proximal tarsal, and distal- tarsal masses, and the metatarsals (fig. 10) are all distinct; but the three elements of the proximal tarsal row are all fused together : the distal was always undivided. The tibia, having starved the fibula, is dilated below and deeply grooved, with extensor tendons in front : it is gently concave behind. The curious knuckle which is strapped to it below has a double condylar face below, and is like two heavy wheels joined by a broad axle. This part is hollowed out, right and left above, for the lobes of the tibia to fit into ; while towards the outer (or fibular) side, there runs upwards a lone: tongue of cartilage, which is bound to the front of the outer tibial ridge ; actually, this band reaches to the tibial ectostosis. On its tibial side it has a square but convex bridge of newer and softer cartilage attached to it, which passes over the deep tendon valley of the tibia.* In the Papers, above referred to, neither Gegenbaur nor Huxley seem to have dreamed of there being more than the astragalus in the large proximal tarsal mass. The latter says (I. c, p. 20) of this part in the fowl : — " The astragalus is a much depressed bone, with a concave proximal and a convex pulley-like distal surface. A process ascends from its front margin in the groove in the front face of the tibia. This process is comparatively short, and perforated by two canals for the tibialis anticus and extensor communis in * In my Memoir on Balaniceps, p. 343, I erroneously ascribed the formation of the tendon bridge to the " ascending process " of the astragalus. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 49 the fowl ; while in the ostrich and emu it is extremely long and not so perforated." Note here that the later band of cartilage had already become ossified and fused with the short ascending process in the pullet's leg described by Professor Huxley ; and here again the anatine type is seen to correspond with the struthious, and to differ from the gallinaceous. I trust that these figures and descriptions of mine will at least suggest to the palaeontologist that he is not observing the primitive condition of the limbs of Dinosaurs, nor, indeed, of the remains of any adult extinct reptile whatever. If, in the development of a duck's leg, such a complete fusion of the three primary proximal tarsals takes place in three days (Plate I., figs. 4 and 10), surely some allowance may be made for the pre-natal transforma- tion of an ornithoscelidan reptile. It is seen here (fig. 10, tb.,fbe., i.) that the lesser fibulare has become completely fused with the larger tibiale, and the intermedium with both : these three were all equally independent of each other. The long tongue-shaped intermedium (/.) is united with the fibular part of the common mass by a shorter, and to the tibial parts by a longer tract of cartilage. The scaphoid, or centrale (c.) is a lunate wedge of cartilage behind the tibial side of the joint, and is not, in the duck, formed into solid cartilage as it is in the fowl. The great distaltarsal (d.t.) has become completely formed, so as to show two concavities above for the condyles of the proximal piece, and also a rounded intercondylar process to fit into the hollow in the front of the upper piece ; behind, it has sent down four ridges, the larger on the tibial side ; these form the tendon- bridges and pulleys (fig. 11). The three main metatarsals (m.t. 2 '*) are seen now to be closely applied to each other, and to be ossifying ; their round tops fit into three concavities in the base of the distaltarsal. The fifth metatarsal (m.V) is still to be seen as a small nucleus of cartilage : the first has not been figured ; it has got down nearly to the end of the shank. Even the condyle of the second, however, is higher up than either that of the third or the fourth. This is an adaptive condition having relation to the aquatic habits of the bird. ROTAL IRISH ACADEMT CUNNINGHAM MEMOIRS, NO. VI. [7] 50 Cunningham Memoirs. Stage 4. — Embryo of Duck, Fourteen Days' Incubation. In this stage the intermedium (Plate I., fig. 12, i.) is still unossified ; but this process begins directly after this time, that is on the fifteenth day, or at the middle of the period of incubation. The tibia (t.) is still distinct from the mass below ; the centrale can be seen as a definite nucleus ; the fifth metatarsal (m.t. b ) is now confluent with the fourth. Stage 5. — Embryo of Duck, Eighteen Days' 1 Incubation. The ossification of the intermedium, which began on the fifteenth day, is now nearly perfect, only the connective tract at tbe base being soft. The ectosteal tract (fig. 13, ?".) begins as a thin bony ring round the bar, below the middle, and rapidly runs to the apex below it : the tibiale and fibulare {tb., fbe.) are still unossified, and are still free from the tibia, above : the toe of the pedate base of the intermedium bounds the round intercondylar con- cavity in which the knob of the distal tarsal fits : the tendon bridge over these is now well developed. Stage 6. — Duckling, Three Days old. In the middle of the first week after hatching, the sections through the ankle-joint show a bone in each of the pulley-like elevations of the proximal tarsal mass ; and also one in the centre of the great distaltarsal. The tibia is still distinct from the former, and the metatarsals from the latter (Plate I., figs. 14, 15, *., tb., fbe., cl.t., m.t.). In one figure (14) the tibiale is cut through, but the lower bony centre is not reached; in the other (15), both the fibulare and the metatarsal centres are exposed ; these are all three of the normal kind of bony deposits for these short segments of the limb. They are " central endostoses," and are a long while coming to the surface ; so that, if the ascending process were in reality a mere periosteal growth of the double proximal tarsal, two Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 51 things would have to be proved concerning it : firstly, that it did not appear until the bird was fully adult ; and, secondly, that it had not its own osseous centre. The merest tyro in anatomy knows that this is true. In the duckling of the first week the "centrale" has degenerated into a mass of fibro-cartilage, forming part of the tendon sheaths at the back of the joint. Water-birds do not conserve this element as an ossified and distinct piece. The Hind-limb of the Swans (Cygnincc). In the almost ripe embryo of Cygnus nigricollis (Plate III., fig. 8, and Plate IV.) the ankle-joint is quite like that of the fifth stage of the embryo duck, except that the intermedium («.) is shorter. After hatching, the growth of the swan's young is evidently slower than that of the duckling — cygnets of a month old being not much more advanced in this respect than ducklings of the first week. Happy in the possession of two of these, which were about equal in size to a teal ( Querquedula crecca), I can show that, whilst the intermedium begins to ossify by the middle of the incu- bating period, the central endostosis, forming the rudiment of the tibiale, fibulare, and distal tarsal, has only reached the perichondrium at the end of a month after that period (Plate V., figs. 8-10); no periosteal deposit is possible as yet ; and, even afterwards, the double mass (when the tibiale and fibulare are completely fused) is covered with articular cartilage, except where it has become fused with the tibial shaft-bone. Thus, the formation of the ascending process, as a periosteal outgrowth, is impossible. The rest of the hind-limb in the swan, and in the Anatidse generally, is constructed for swimming, and even for diving, in the clucks, and especially the mergansers. The two inner and larger post-tarsal ridges form a bridge over a flexor tendon, as in the fowl : the tarso-metatarsus is compressed laterally : the fourth digit is elongated, the second and first elevated, and the latter is small and free. [7*] 52 Cunningham Memoirs. Wing of Embryo (* ripe) of Falkland Island Goose (Chloephaga poliocephala). When Dr. R. W. Shufeldt called the displaced first distal tarsal " pen- tosteon," five carpals were known in the young bird ; although, in almost every case, only the two proximal pieces remain distinct. Dr. Morse* satisfied himself that the so-called "ulnare" was a double nucleus. And he was right : it is so, morphologically ; and is, not unfre- quently, actually subdivided into two, or even three nuclei. In a Paper, soon to be printed, f I have shown that the " radiale," also, may be in two pieces : for a time it is so in Opiosthocomus, the subject of that Paper ; and I find it so, also, in Falco tinnunculus. The subdivision of the ulnare is seen in two of the most terrestrial forms of the Chenomorphoe, namely, in this goose and in the screamer ( Chauna chavaria). This is the more interesting, because the long-legged terrestrial geese are very apt to have spurs on their wings [e.g. Chenalopex, Plectrop- terus) ; and these spurs have their highest development in the unwebbed Palamedida3 — birds with cultratc bills. Thus, whilst on one hand the Chenomorphse are walking, or, at most, wading birds ; on the other, the mergansers have certainly a smack of both the cormorant and the diver in their nature. This makes it extremely difficult to conceive of the whole bundle of Chenomorpha3 as branches of one stem. In the ernbryo of Chloephaga poliocephala the claws are well developed in the wing (Plate V., figs. 12 and 13), that on the index (dg. 2 ) being especially long. The parts at the lower hinge of the wing are as remarkable for their great number as these parts in an adult bird generally are for their fewness. The radiale (re.) is single; but the thick U-shaped ulnare (ue., c. 1 , tv) has both its crura segmented across, almost perfectly, to form an outer and an inner " centrale " (fig. 14, c. 1 , c.' 2 ). At this stage the three distalcarpals (d.c. 1 ' 3 ) are clearly marked out ; and on the edge of the third metacarpal, on * Loc. cit. f In the Transactions, Zoological Society of London. Me. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 53 its flexor side (figs. 14, 14 a ), there is a distinct rudiment of a fifth meta- carpal (m.c. 6 ). On the proximal part of the second metacarpal, at the outer face of its ulnar edge, there is a distinct semi-lanceolate accessory cartilage (m.c. 2 1 ) : the accessory part to the proximal phalanx of the digit (dg. 2 1 ) has coalesced with the main piece on its ulnar side, and is ossified by it, not independently. The sub-division of the ulnare is not so evident on the right side as on the left. When the spur is formed on the " trochanter" of the first metacarpal (m.c. 1 ) in some of the geese, there is in this case a con- siderable tract of fibro-cartilage ready for any such adaptive growth. Whilst the peculiarities of this embryo, and of that of the kestrel, were the only types in which I had seen this remarkable sub-division of the radiale in one, and of the ulnare in the other, they caused me much anxiety : now I find that this is not so rare a condition as I had sup- posed. But for a quarter of a century I had been aware of a divided " ulnare" in Chauna chavaria. In that bird, on the left side, there are two proximal carpal bones attached to the ulna (Plate II., fig. 13, tie., c.)\ the outer is the outer centrale, and the inner is the "ulnare" proper: this is one-third larger than the other. Here, again, this peculiarity is seen on the left side, and not on the right. In the other Palmipeds we shall see parts of the wing-skeleton that have hitherto been quite unnoticed. We are only just waking up to the fact that the things that now are have not been so always since the foundation of the world. In the cultrate Palamedidse, and in some of the lamellirostral forms, the wing has spurs similar to those on the shank of the Phasianidse. Dr. Sclater* quotes, with approbation, the views of Mr. J. Amory Jeffries, t His words are : — " Mr. Jeffries shows definitely, for the first time so far as I can make out, that the spurs which are in some cases found on the wings of birds are of an entirely different nature from the claws also met with on * Ibis, 1886, p. 147. f "On the Claws and Spurs on Birds' Wings": Proceedings, Boston Soo. Nat. Hist., vol. xxi., p. 301. 54 Cunningham Memoirs. the same organs, and have in fact nothing whatever to do with them." In a note on this same page, Dr. Sclater says : — " Even so recent an authority as Dr. Selenka* has confounded together the spur and claw of birds. His account of the subject contains several serious misstatements, and is obviously not based on his own examination. Owen's ' Anatomy of Verte- brates ' (cf., op. cit. II., p. 74) likewise confounds claws and spurs. It must be even admitted that Nitzsch (usually a model of accuracy, and the first scientific describer of the claws of birds) did not quite understand the dif- ferences between claws and spurs."f I must also, myself, confess to having confounded claws with spurs in my Paper " On Bala3niceps,"J and also in that " On Gallinaceous Birds and Tinamous,"§ I have put the hallux as the second toe, considering the spur of the cock to be the abortively developed first toe. That error was corrected by Gegenbaur,|| and his views were adopted by Huxley. *\ The hind-toe or hallux does certainly correspond with the innermost, or first toe, in a lizard's hind-foot, just as the pollex of the bird corresponds with the innermost digit of the fore-foot of a lizard. The normal number of phalanges determines this, namely from two in the first to five in the fourth, and then a diminution in number in the fifth. But this matter cannot be settled and made sure for ever to science by the study of adult birds. If Dr. Sclater had compared the wing of Chauna derbiana (op. cit., p. 150, fig. 2) with Dollo's figures of Iguanodon bernissar- tcnsis** or even with some of my figures of the early state of the digits of the wing, ft his sense of certainty would have yielded to the confusion of * Bronn's " Thier-Reieh " : Aves, p. 75. t See his " Osteographische Beitrage, No. 5": Ueber das Nagelglied der Fliigelfinger, besonders des Dauraens : Leipzig, 1811. \ Transactions, Zoological Society, vol. iv., Plate LXVI. § Ibid., vol. v., Plate XXXV. || " Vergleichend-anatoniische Bernerkungen uber das Fussskelet der Vogel " : Arcbiv. fur Anat. und Phys., 1863. ^1 Proceeding's, Zoological Society, 1867, p. 417. ** Bull. Mus. Roy. Hist. Nat. Belg., t. i., Plate IX., figs. 2, 3. ft Philosophical Transactions, 1888, B., Plate LXIL, figs. 1, 2. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 55 mind attributed by him to Owen and Nitzsch. In that huge extinct reptile, with its extremely avian hind-quarters, both the pollex and the fifth finger diverge at a right angle from the rest. If the horn-core and the small bone at its base had been anchylosed to the other parts, nothing would have appeared more certain than the precise homology of that pollex with the upper spur in Palamedea and Chauna. The difficulty does not, however, cease here. In a continuation of his valuable Paper,* Dr. Sclater shows that the large spur on the wing of the spur-winged goose (Plectropterus gambensis) is on a projection of the racliale, or inner proximal carpal. Nothing, to those who are satisfied with adult anatomy, could be clearer than this proof that the spurs are of an entirely different nature from the claws also met with on the same organs, and have, in fact, nothing what- ever to do with them. But we must, as the saying is, " go slowly that we may make the more speed." I would remind Mr. Jeffries and Dr. Sclater that, in the evolution of the cheiropterygium from the ichthyopterygium, claws are a late specializa- tion. Only Dactylethra, amongst existing Amphibia, possesses them. In the Reptilia, as in Dactylethra, the straight nailless terminal phalanges grew out into the skin-fold, and there received a horny covering, both the dermal layer and the terminal phalanx becoming covered, and so forming a hooked claw. But the normal digits of the highly specialized pentadactyle cheiroptery- gium are not the only parts we have to deal with in the limbs of birds and mammals. Neither birds nor mammals are the descendants of true reptiles, but of much more ancient and generalized types. I find, taking the birds as a whole — in this bird and in that — a row of cartilaginous nuclei inside, or in front of, the normal first digit, or pollex. These I shall describe in a Paper succeeding the present. Not only these segments of a " pre-pollex," but intercalary segments are also common in the developing wing of a bird — feeble f orkings of the digits ; a reappear- ing, or rather a lingering, of vestiges or remnants of some archaic polydac- tyle limb. In the common fowl the core of the cock's spur is at first a solid * Ibis, 1886, pp. 300-301, fig. 3. 56 Cunningham Memoirs. fibro-cartilage — a " pre-hallux " : it fuses with the second metacarpal after it has become ossified. Now, the presence of two spurs on the same limb in the shank of Polyplectron, and in the wing of Chauna,* seems at first blush to decide the merely adaptive and, as it were, accidental nature of these spurs. My answer to this is that there are two phalanges which appear between the pollex and index in birds ; and that the distal of these two segments is present in by far the greater number of Passerine birds. That segment is a triangular plate of true hyaline cartilage, autogenously ossified by endostosis, and becomes fused with the ectosteal sheath of the second meta- carpal, near its lower end ; and is manifestly the true homologue of the horn-core of the distal spur in the Palamedidse. The Alcid^e. This palsearctic family, which has only lately lost its chief — Alca impennis — is still rich in forms ranging in size, if we take in the great lost species, from a large goose to a small gosling ; for Ciceronia pusilla scarcely exceeds the size of the latter. These birds are the isomorphs of the nearctic penguins (Spheniscidas)*; and, in the case of the great auk, the approach of the northern to the southern type was very close. As to the penguins, they are a much more isolated type than the auks and guillemots, and are also much more uniform. Specialized to the uttermost in one direction, they are nevertheless evidently archaic. The tendency of the Alcidpe is in the same direction : they appear, however, to have begun to modify in this direction later than the penguins, and the transformation is only partial. This, however, is pure conjecture. Pro- fessor Huxley's " Classification "f breaks down most among these water- birds. His " Cecomorphse " are a promiscuous flock of Palmipeds driven together by the "whiff and wind" of his taxonomic force. If it pleases * Sclater, op. cit., p. 150, fig. 2. f Proceedings, Zoological Society, 1867, pp. 415-472. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 57 him to call the group the gull-form, he must not be surprised if the next classifier should scare them all apart again. Dr. Marsh did this unconsciously ; for his toothed birds show, if they show anything (and they are the most lucid revelation we have had on this subject as yet) that the divers and the gulls were as far apart in the secondary epoch as they are now. The Ichthyornis is evidently an archaic toothed gull ; and the Hesperornis, which anticipates the modern terrestrial Ratitse, has, like its nearest living relatives, the grebes and loons (Podicipitidse, and Colymbidae), cylindroidal vertebrae down to its sacrum. Ichthyornis, a Carinate, has its pre-sacrals amphiccelous — a condition scarcely improved upon by the existing gulls in their hinder dorsals : their cervicals arc cylindroidal. This modern group of the Alcidge, like the existing gulls, have opisthoccelous dorsals ; and so have the penguins and the plovers, the cormorants and the darters ; but grebes and loons, like Hesperornis, have the whole pre-sacral series cylindroidal ; in which they agree with the modern Ratitae on one hand, and with the petrels and all the " Steganopods " or Tolipalmatse, except the cormorants and darters (Phalacrocoracida?) and Plotidse. In respect of the dorsal vertebra? the Alcidaj and LaridaB agree, and their skull* is very similar fundamentally; but so, also, is that of the aberrant Limicolse, e.g. Ononis, Attagis, and Thinocorus ; and the Rallidas, also, come very close in this respect. The fact of the case is that, in great numbers of those schizognathous birds that abort their basi-pterygoids, there is a wonderful conformity in this respect. But the skull of the penguins is also one of the same type ; it is some- what more archaic certainly ; but there is nothing in that part, nor in the rest of the bird, it seems to me, sufficient to warrant the separation of that one family into a sort of order — the " Spheniscomorphse " — whilst gulls, skuas, petrels, auks, guillemots, loons, and grebes are put together by force into a sort of " happy family " : their harmony will end the moment the personality of the " keeper" ceases to dominate them. * See Huxley, op. eit., p. 430, figs. 10, 11. EOYAL IUISH ACADEMY CUNNINGHAM MEMOIRS, NO. VI. [8] 58 Cunningham Memoirs. In some respects the gulls and auks agree ; they are as unlike, on the -whole, as it is possible for two groups of water-birds to be. The Morphology of the Alcid^e.* The Cranium in Uria troile. Stage 1. — Skull of Embryo of Uria troile, One-third ripe. The chondrocranium, at this stage, is fully formed (Plate VI., fig. 1). The basal part is the most instructive ; the other regions will come under notice in the more advanced stages. f The transitory, as well as the permanent, parts of the endocranium are well developed ; much of the latter will undergo osseous transformation. The chondrocranium, at present, has some little likeness to that of a skate, the skull proper being so short, and the pre-nasal rostrum so long ; but this is a high skull, like that of a perch, and that of the skate is a low one. Here the brain is tilted upwards in front, and lies on the coping of a large wall : in the skate, as in the Amphibia, the brain lies down on the flat basi-cranial floor. The chondrocranium has not yet begun to ossify ; the notochord (nc.) is still large ; but the parachordal tracts have united across it, have coalesced with the cartilaginous ear- capsules, and have sent upwards lateral growths that have met, right and left, and become con- fluent, over the hind brain. Behind, the double tract of cartilage has formed the almost hemispherical occipital cond}de (oc.c.) ; and, in front of * For the osteology of the same parts of the embryo of Alcidoe, see my " Shoulder-girdle and Sternum " (Plate XVIL, figs. 10-14, pp. 146-148) ; and of the adult bird, see Owen, " On Alca impennis," Transactions, Zoological Society, vol. v., Plates LI.-LIL, pp. 317-335 ; and It. W. Shufeldt, "Osteology of Arctic and Antarctic Water Birds." — Journal of Anatomy and Phy- siology, vol. sxiii., Plates I.-V., pp. 1-39; ibid., Plates VII.-XL, pp. 165-18G ; ibid., pp. 400-558. f For figures and descriptions of the very similar skull of Gavia ridibunda, see Transactions, Linnean Society, series 2, vol i., Plates XXVL-XXVIL, pp. 140-151. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 59 this, and further outwards, we see the passages for the hypoglossal (xii.), and vagus and glossopharyngeal nerves (ix., x.). The auditory capsules occupy a very large space in the sides and hase of this delicate semi-transparent chondrocranium. The lagenar (««.), and the canals (a.s.c., h.s.c., p.s.c.) shine through the thin, clear walls. In front of these captsules the base of the skull suddenly closes in ; the notochord is lost to view, for it ascends into the post-clinoid wall (see in stage 3, fig. 8, p.cl.). In front of that wall there is a round opening — the pituitary space, which receives a secondary floor, but is not, as in our cranium, floored with cartilage — the seat of the " sella turcica." That open hole was formed by the growth of the trabecular round the pituitary involu- tion ; there they met, and coalesced with, the parachordals or investing mass enclosing the notochord behind. Meeting in front of this open space, the trabecular run forwards, and, apparently, at this stage, form the long, thick, rounded balk of cartilage which runs forwards to the end of the beak. But a little in front of the pituitary space there was formed a median cartilage, which wedged itself in between the other two, and can therefore be fitly called the inter tralecula. The paired trabecular only run half way to the end ; flattening out, they grow upwards and help to form the orbito-nasal partition wall (see, in 3rd stage, fig. 8, tr.,p.e., s.n.). The trabecular, in some cases, send out flat cornua where they end.* I do not see these parts in Uria. The foremost third of the long wall is free ; it has no wall growing upwards from it : it is a large Ratine pre-nasal rostrum. Just when it is becoming free, it is somewhat twisted, as also is the primary mandible below (fig. 2, mk.). I shall refer to this in the next stage. The large alisphenoidal, and the aborted orbito-sphenoidal wings will be described in the 3rd stage (fig. 8, al.s., o.s.). Instead of the direct basi-cranial outgrowths for articulation with the pterygoids, as in lizards and the Ratitar,t these birds, like the fowl and most other Carinatar, develope separate remnants of those basi-pterygoid outgrowths (fig. 1, b.pg.). In these, and many other birds, these parts, * See in Chick, Philosophical Transactions, 1869, Plate LXXXI11., fig. 4, s.v.l. f See Philosophical Transactions, 1866, Plate VII., figs. 2 and 4, tip. 60 Cunningham Memoirs. and the joint formed by them and the pterygoids, is only a temporary structure ; and in many of the passerines the remnants themselves are suppressed.* The pier of the first visceral arch — the quadratum (•) is seen ; and a large, squarish bone — the prootic {pro.) — is formed round the holes for the facial and auditory nerves (vii., viii.). Between the side of the supra- occipital and the large arch of the anterior semicircular canal (a.s.c.) there is a semicircular space fitted only with membrane ; this is the lateral occipital fontanelle which characterizes the skull in so many water and wading birds, not excepting the Anatida?, which are so unrelated to the rest.* The articular («>-.) is enlarging, but I do not yet see the separate endosteal centre in the articular enlargement of the mandible; the outer centre appears some weeks before the inner ; it is some years before the latter appears in the green turtle ( Chelone viridis); and its ectosteal articulare might * The final purpose of these windows in the back of the head, in these birds, which are made and then filled-up, as though they had been taxed, is not possible to conceive. The middle occipital fontanelle, in owls and pigeons, is a mere economy of stuff. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 71 easily be mistaken for a mere parosteal splint by a young and incautious morphologist. The ectocranium at this stage is seen as an admirable supplemental growth of bony scales over and around the primordial skull and face. The imbrication of these "natural selections" from the inner face of ancient ganoid scales, notwithstanding the extreme degree of specialization that all these parts have undergone, is still as visible as that of the armour of any ancient type of vertebrate. And yet, almost all these superficial bones have their names from human anatomy, and a beginner can see the maxillary, inter-maxillaries, nasals, frontals, parietals, squamosals, vomer, &c. (Plate VI., fig. 8, mz.,p%., n.,f.,p., sq., v.). Archaic parts, however, not seen in our own skull, are seen here, namely, the rostral basitemporal parts of the ancient parasphenoid Qtra.s., b.t.) ; and on the mandible all the reptilian splints except the coronoid (which also is present in the arboreal birds, but not in these and many other Precoces). But the dentary (d.), the splenial (sp.), the supra-angulare (s. ag.), and the angulare {ag.) are well developed here, but little altered from what is seen in ganoid fishes. From the time of hatching to the first birthday of the bird, in one year nearly every trace of the old landmarks are removed ; only in the specifically ornithic jaws and palate are the elements at all kept apart. About half of these are required in this most mobile apparatus. At this point, my work is supplemented by Dr. R. W. Shufeldt's valuable Papers, especially in that which treats of the skull of the adult guillemot.* In one or two points as to the ossification seen in the skull of the adult Alcidae, my valued fellow-worker has not quite caught my meaning in certain of my memoirs on this subject. In his earlier Paper on Alca in which the skeleton of Alca tor da is described, f Dr. Shufeldt mentions a little bone attached to the lachrymal, and which he supposes is the one called by me " os uncinatum " in my Paper in the Encyclopaedia Britannica, vol. 9, art. Birds, p. 714. The bone * Jour, of Anat. and Phys., vol. xxiii. (vol. iii. n. s.), pp. 166-171, Plate VII. \ Ibid., vol. xxiii., p. 8, Plate I. 72 Cunningham Memoirs. referred to is, however, merely a limited ossification which takes place in the hind part of the coiled inferior turbinal. This bone in my specimens is an elegant open ring, the bony deposit having affected the whole coil to a short extent; it is formed in front of the pars plana, where these two parts are confluent.* But the true remnant of the os uncinatum is formed in the intero-external angle of the pars plana (Plate VII., p.p., Plate VI., fig. 4, p.p.), which is the homologue of the ethmo-palatine of the frog.")" Besides the special middle turbinal centre which ossifies nearly all the pars plana of these birds, there is formed in the adult a small milioline bone in the angle just where the lachrymal ends below. There are two such nuclei on the right side, some on the left in one of my specimens of the skull of Uria troile, and one in the rest of my Alcido?,, namely, Alca torda and Fratcrcula arctum. In gulls of the first year this angle remains unossified ; but in old specimens it becomes a distinct os uncinatum, almost as well developed as in the albatross. In an old Larus argcntatus it is triangular, and the lower and longer side which is notched, is two millims. in extent. In an old laughing-gull ( Gavia ridibunda) it is a wedge-shaped bone, 1 75 millims. long, and 1 millim. wide above. The ossified ends of the inferior turbinate are very distinct and elegant in all my specimens of Alcidas ; and they have the same development in Alca impennis, as my friend Frederic A. Lucas has shown me. In a letter to me, dated January 22nd, 1888, he gives some descriptions and careful drawings of these parts, and also of another important and much larger osseous centre. This larger bone is the ossification of the thick isthmus of cartilage shown in my third stage in Uria troile (Plate 6, fig. 8, c.f.e.). That isthmus remains, for the segmen- tation of the wall is not perfect, and the septumnasi (s.n.) in front of it is arrested. This fore-wall is feeble in the adult of these Alcidas. This part is broad and carinate ; the perpendicular ethmoid (p.e.) stops short at the point it has reached antero-superiorly in my third stage ; and the roof and keel in front of it is ossified as a separate thick wedge of bone. This is seen in Alca impennis, A. torda, Uria troile, and Fratcrcula arctum, and * Sec Fowl's Skull, Plate 86, figs. 6 and 8, pp. 1-16. f See my Paper ou "Eemnants and Vestiges," Proc. Roy. Soc, vol. 43, Febr. 23, 1888, pp. 400, 401. Me. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 73 is mentioned by Dr. Shufeldt in his description of the skull of Uria (op. cit., p. 170) as existing both in that bird and in Alca. In old species of Uria troile I find it 9 millims. wide behind, and 9 niillims. long ; and in front of these is another bone like it, but only one-fourth the size. In an old Gavia ridibunda there is a similar septal bone behind ; then a small nucleus ; in front, the whole top of the septumnasi is ossified, and has coalesced with the nasal processes of the premaxillaries. This septal ossification, generally in one piece, is found in many of the Grallse and Palmipeds, to say nothing of arboreal types. I find the main or hinder piece in Podlceps minor, Rallus aquaticus, Porplujrio poltocephalus, Ardea cinerea, and in Nycticorax. The basi-pterygoids are absorbed in the adult ;* but the pterygoids retain a little ingrowth towards the place where they existed in the embryo. For the rest the reader is referred to Shufeldt's excellent figures and descriptions. I have purposely referred to the structure of other types of water-birds and of their grallatorial relatives. Guided by the skull alone, we might tie into one taxonomic bundle many a family of these birds : that is a clear fact, and most important in ontological research. But it is a misleading thing to do this in ornithology ; — a gull is one thing, a guillemot is another, and a plover is diverse from both. Let us keep our evolutional speculations apart from our taxonomic work: "there is no need of such varieties " in that field of Science. The Vertebral Chain and Bibs in Uria troile. 1st, 2nd, and 3rd Stages ; and 4th, or Adult. It will be convenient to describe these stages together for the sake of the mutual light shed by them. The vertebral formula in this type is as follows : — C. 15 (two or three ribs free); D. 7; D. S. 2 (second rib im- perfect); L. S. 3 ; S. 4 ; U. S. 5 (riblet on first of these fused); Cd. 10 + 3 : Total 49. * See in Alca tarda, Shufeldt, op. cit., Plate I. ROYA1 IRISH ACADEMT. CUNNINGHAM MEM01BS, NO. VI. [10] 74 Cunningham Memoirs. In the first, stage (Plate VIII. , fig. 1) there are only twelve vertebrae between the hip-plates instead of fourteen : this is the ornithoscelidan stage. In the second stage there are three distally articulated ribs on the left side, at the end of the cervical region (Plate VII., c.r.) : the first of these becomes fused in the adult. It is worthy of remark that these birds, which feed on " small fishes and Crustacea,"* should have a very strong neck with short vertebrae that have strongly marked processes, whilst the heron, which, as a rule, deals w r ith large prey, should have long, smooth, slender cervical vertebrae. I suppose it is due to the more hurried manner in which they feed. The meditative heron, when the necessity is laid upon him, suddenly — swift as an arrow — seizes his prey. As compared with the Anatida? of the same size, the e-uillemot has fewer cervicals, and each bone is shorter ; more dorsals — seven instead of five ; fewer dorso-sacrals and uro-sacrals ; and a rather longer, but feebler, caudal series. The spines, both upper and under, are strong; the riblets are well developed, but do not exist on the atlas. On the left side the last three, on the right the last two, are free. In the second stage (Plate VII.), in the pre-sacrals, ossification has taken place in the centra, neural arches, and riblets ; these latter are losing their distinctness. The odontoid element, already united with the axis, the fore part of the centrum of that joint, and the base of the atlas, are not yet ossified — one centrum and two intercentra. Below, where the ribs are articulated, the cervicals become rapidly approximated to the dorsals ; the spines become square and crowded ; below, the spaces are bifurcated and dilated, right and left. In the general sacrum, and in the caudal region, the centra are acquiring an osseous deposit in the sheath of the notochord, but not as yet the neural arches. In Stage 1 the vertebrae are unossified ; in the pre-sacral region the notochord, which had shown contractions at the joints, had become largest there, and also was constricted so as to have two new swellings inside the cartilaginous centrum. Behind the dorsal region (Plate VIII., fig. 1, nc.) only two moniliform swellings are seen in each centrum, and these are lost * Macgillivray, "Manual of Ornithology," 1842, p. 213. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 75 in the caudal region ; yet there the notochord has the amphibian character of being largest at the intercentral spaces.* Hence, this vertebral chain has evidently, like the rest of the organism, been subjected to some dominating force that has fashioned it anew for some further and higher ends in life, so that some unsightly creature, not perhaps dissimilar to Siebold's gigantic salamander, or the eel-like Siren lacertina, has been "clothed upon" not only with a warm, soft, feathery and downy vestment, but has had its whole structure metamorphosed into this "rich and strange" type. Nearly half a hundred links have been developed in this cunningly wrought chain, where, perhaps, a hundred did exist in the low quasi-larval ancestor. It is passing strange that a blind force should produce such " new things in the earth." The stunted condition of these post-dorsal vertebrae, the fore half becoming fused and the hind half arrested, is in harmony with the rest of the structure of this Pygopod ; nevertheless, had it been necessary, a moderate amount of elongation would have made the eighteen vertebras that are behind the true sacrals into the tail of a Saururous type as long as the rest of the spine. The last four imperfect segments formed round the notochord become the uropygial joint ; the nine in front of that keep distinct ; their transverse processes (diapophyses) gradually decrease to the end. In this first stage the ribs on the first dorso-sacral are developed — are almost complete below ; but on the second they are in three pieces, the proximal (Plate VIII., fig. 1, s.r.) being a very small bar — simply a rudiment of the capitulum and tuberculum. On the first uro-sacral there is an attempt at the formation of a distinct rib bar. Hence, this part of the axis is seen to be less perfectly developed than in the Anatidse. Before hatching, in my third stage (Plate VIII., figs. 2, 3), the whole of the general sacral series is enclosed between the ilia ; and the centra, but not the neural arches, except in the first dorso-sacral, are ossifying. These bony patches, formed, at first, round the notochord, are transversely oval : the widest are in the swollen proper sacral region. These tracts are formed * See Proceedings, Koyal Society, 1888, p. 466; and Foster and Balfour's "Elements of Embryology, 1874," p. 157. [10*] 76 Cunningham Memoirs. as far back as to the last four imperfect segments. Under the largest of these, and under all the rest of the free caudals, there is, at the fore edge of each centrum, a small milioline intercentrum ; above (fig. 3), four vertebrae have a spine, that on the fourth being the smallest. The last lumbo-sacral and those of the four proper sacrals are mere round belts; then a small tubercular spine reappears, and is hardly lost on the last of the four uropygial segments. That the cervicals in the adult are short is seen by the following measurements: — The centrum of the eighth, or longest of this chain, is 11 millims. long, the whole length of the vertebrae, with its oblique processes, being 16 millims., and the width over the prezygapophysis 14 millims. The spines are well developed ; the four next behind the atlas have upper and lower spines ; the tenth has a large lower spine ; then this decreases, and there are three such outgrowths on the fourteenth. On the fifteenth, or last cervical, and on the first two dorsals, the lower spine is double, and dilated transversely, as in the loon (Colymbus), and another fish-eating bird not related, the kingfisher (Alccdo ispida). The other five dorsals — the first dorso-sacrals — have long simple spines, pedate below, sloping from before backwards ; these spurs are like those of the grebes (Podiceps), but are not so long. In this point the guillemot is intermediate between the loon and the grebe, as Hesperornis is in its general structure. The upper spine reappears in the last three cervicals. Thus, the last of these, the seven dorsals and the two dorso-sacrals, form a gently arched series of square spines, closely fitting— that is, with only a small tract of elastic ligament between them, and tied together by fine bony tendons. The dorsals, one with another, and the last of these with the first dorso- sacral, are united by opisthocoelous joints, that have paired overlapping processes, such as I have described in the oil bird.* All the cervicals, even the last or fifth in its junction with the first dorsal, are heteroccelous, or cylindroidal. The caudals are feebly amphiccelous, and have no joint cavity. In the guillemot the atlas has no rib bar enclosing the vertebral artery, as in the duck and its congeners. It has one, however, on the axis, which * Steatornis, Proceedings Zoological Society, 1889, Plate XVIII., p. 174. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 77 is not present in birds generally ; these riblets are developed into a long style on the 3rd, 4th, and 5th, and these become short, and the retral part is lost. The free rib on the 14th is 8 millims. long; that on the loth is almost as long as that on the first dorsal, and it has an ossified uncinate cartilage (see Plate VII.) ; these parts are long, and are present also on all the seven dorsals ; thus there are eight pairs of them; they do not become fused with the ribs. The ribs are extremely long, slender, and sinuous in form, and are articulated to equally delicate sternal ribs at an acute angle. The first forms, when at rest, a right angle merely; this is seen in an exagge- rated form in the embryo (Plate VII.). Of course they are somewhat opened out in inspiration. The last dorsal rib in Uria troile is 95 millims. long, its sternal piece 81 "5 millims., a little more than half the length of the same parts in Alca impennis.* The cinctures formed by the first dorso-sacral rib just fall short below ; that of the second dorso-sacral is in three pieces on each side. Above, a delicate bridge of bone is ankylosed to the vertebra at both ends ; below a distal piece appears, 40 millims. long, attached to a sternal piece, 50 millims. long ; the average breadth of these needles of bone is - 75 millims. Sitting up, in full dress, these birds have a bulky look ; but they are much more compressed than the duck or the penguin ; and their trunk is not only very long for a bird, but also very deep. In the loon ( Colymbus septentrionalis), and in the great diver (C. glacialis), as also in the grebes (Podiceps), the body is very flat or dejn'essed, strikingly so; compare Alca impennis [op. cit.), and Brandt's figures of the skeleton of the loon {Eudyptcs {Colymbus) septentrionalis), and of Podiceps auriius.f Besides, in these latter birds the ribs are much shorter and stronger than in the Alcidse. Altogether, in comyjaring these water-birds, each family seems to me to be isolated, and they are probably much less nearly related to each other than they seem to be, the similar adaptive modifications giving them a misleading isomorphism. In my second stage (Plate VII.) the ribs are accpiiring a long ectosteal * Owen, Transactions Zoological Society, vol. v., Plate LI. f " Zur Osteologie der VSgel," 1837, Plates XVI. and XIV. 78 Cunningham Memoirs. sheath, the sternal ribs (s.r.) are not yet ossified; their ossification takes place in the same manner as in the vertebral ribs. It is evident that sometimes the last cervical rib may join the sternum by a sternal piece, although as a rule in Uria troile, Alea impennis, and Aha torda, there are only seven pairs of sternal ribs. This additional sternal exists in my third stage,* although there are only seven in the first stage (ibid., fig. 10), and in the second stage also (Plate VII. of this memoir). Also, in the same figure of the thorax of the third stage, the uncinate cartilages (c.a.) are seen to have an adze-shaped dilatation above, when they are fully formed. Even this undergoes change, and the enlargement is much less evident in the adult. "With regard to the number of perfect cinctures in the thorax in all Dr. Shufeldt's exquisite figures, f there is only one with eight perfect sternal ribs, and this is on both sides (Plate III., fig. 18, and Plate IV., fig. 20, p. 23). My specimen has only seven on each side ; and some of the small forms of Alcidse figured by Dr. Shufeldt (op. cit., Part III., pp. 400-558) are shown as having only six. The Sternum and Shoulder-girdle of Uria troile, Embryos and Adult. My dissection and drawings of the sternum of the first stage made long ago (op. cit., Plate XVII. , figs. 10, 11) show that the metasternum is small at first ; at that time it is no longer than the proper costal tract ; in the adult it is three times as long (see Shufeldt). Why in these birds, which have a tendency to abort the wing into a mere paddle, and in Tinamous which have short wings that they have scarcely the sense to use, the meta- sternum should be so extremely long, whilst in gulls, cormorants, the tropic bird (Phaeton), and in the frigate bird (Tachypetes), it should be so short, is to me, not at present engaged in myology, an anomalous fact. The mechanism of flight in all these birds should be studied in reference to this ; for the metasternum is, like the sternal keel, a thoroughly avian structure. In Mammals it is a very feeble structure ; and in its earlier appearance in Reptiles (Stellio, Crocodilus, op. cit., Plate XL, figs. 1, 2, 7, and 8) it is * See " Shoulder-girdle and Sternum," Plate XVII., fig. 14. t Jour, of Anat. and Phys., vol. xxiii. Mr. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 79 scarcely stronger than a rib. The common granular plate in which the rib, at first, ends below, soon chondrifies, and then the right and left moieties meet, unite together, form a keel, and become segmented from the lower costal segments, or sternal ribs (op. cit., Plate XV., fig. 1). In my first stage all this is complete, the structural relations are perfect ; but the relative proportion of the regions undergoes much after-change. In the second stage (Plate VII.) the rapidly growing embryo has its sternum quite similar to that of the adult, and the metasternum is already twice as long as the costal edge. The pre-costal process (p.cp.) has room on it for two more sternal ribs, which might have grown down from the neck. The rostrum, a special avian outgrowth,* and not a further sternal rudiment, is already formed as a semicircular figure-head, separated from the sharply-produced keel (st.k.) by an almost regular semicircular notch. From that point to the flat, thin, keelless hind-part of the middle metasternal process, the outline of the keel forms a large part of a quad- rant. This convexity of outline is also seen in the body of the sternum, which at this time bellies downwards, the thoracico-abdominal cavity being pregnant with the copious viscera, and a huge mass of still unused food- yolk. The lateral metasternals (m.st.) are separated by a round notch from the middle plate, and are only half as long as its keelless part, behind the fore end of the notch. In the third stage (op. cit., Plate XVII., fig. 14) the sternum is rapidly approaching the adult form, which is well illustrated in Miss Beatrice Lindsay's Paper (op. cit., p. 690, fig. 1), and still better in Dr. Shufeldt's 4th part (p. 538, fig. 1, and p. 546, fig. 4). The sternum straightens out very much, and the line of junction of the keel and body becomes sinuous, for it rises in the middle of the metasteimum. The keel projects its angle in front of the large deep rostrum, and ends behind in a thickened edge, 3 millims. wide ; beyond this about 7 or 8 millims. of the rounded end is unossified. The rostrum comes up well between the coracoid grooves. The whole bone is very evenly oblong ; it measures 37 millims. across the tips of the pre-costal * Lindsay, Proceedings Zoological Society, 1865, p. 707. 80 Cunningham Memoirs. processes, and also across the outer metasternal processes, and only 31 millims. behind the last sternal rib. The whole median length is 123 millims. — nearly four times the average width ; and the keel is 128 millims. long, measured in a straight line above its gently curved lower limbate edge : its greatest depth is 30 millims. The depth of the notches in the metasternum varies in individuals ; in my specimen of an adult they reach half-way to the last sternal rib, and the lateral bars are 20 millims. long and 4 millims. wide. The gently descending series of the seven transverse costal condyles look equally outwards and upwards ; thus the costal cinctures swell out above the sternum. I have noted down this great length and narrowness in the guillemot, both for comparison with the short-breasted gulls,* which come so near the Limicolas in this respect, f and also with the loons.J In the gulls the sternum is both narrow and short ; in the loons it is as long, or nearly so, as in the Alcidae, but much wider. These long sterna had their counterpart in an arrested condition due to the abortion of the wings in the extinct Hesperornis.§ In that bird the sternum, and also the furcula, are almost exactly like those of my third stage of the guillemot.|| Even the skull itself is of less value to the ornithologist than the sternum ; it will be seen at once that this statement is somewhat remarkable as coming from one so partial to the skull. And yet, notwithstanding this, the Alcidae, in several important respects, come nearer to the Laridae than to the other divers (Urinator, Eudyptes, or Colymbus), for these latter forms, with their quasi-ancestor Hesperornis, and the grebes, have all their pre-sacrals cylindroidal.^f The ossification of the sternum in the Alcidae is by a very generalized sort of endostosis, the lophosternum having a very short independence of the * Shufeldt, Part i., Plate IV., fig. 2. j ^id., figs. 22 and 23. \ Shufeldt, Part ii., Plate VIII., fig. 7 ; and Brandt, op. tit., Plate XVI. § Marsh, op. cit., Plate VII. || Shoulder-girdle and Sternum, Plate XVII., figs. 10, 11, and 13. ^f The nomenclature of these birds is very confusing. E. Nitzseh (Pterylography, Ray Soc, 1867, p. 152, Plate X., figs. 10, 11, and 12) calls the grebes Colymbus, and the loons Eudyptes ; whilst Macgillivray (Manual, 1842, pp. 200-206) calls the grebes Podiceps, and the loons Me. W. K. Parker. — Morphology of the Duck and the Auk Tribes. 8 1 pleurostea. The shoulder-girdle of the g-uillemot* has a falciform scapula (so.) nearly twice as long as the coracoid (or.). In the first stage (op. cit.) the axes of these two bars are coincident ; they are ossifying separately, but are only half free from each other at the shoulder-joint. On the fore part of the head of the coracoid there is a small continuous remnant of the precoracoid, which becomes the clavicular process. In the third stage (op. cit.) there is a separate nucleus of cartilage — an external precoracoidal remnant — -which becomes part of the ramus of the f urcula, after undergoing endostosis ; and it forms a shelf, on which the large f or wardly- curved head of the coracoid rests ; that is a flat synovial joint. This structure can be seen even on the inner aspect, f The shaft of the coracoid is moderately slender, and the epicoracoid below has a dilated hook at its hinder angle.J The clavicular rami are largely curved forwards above, and the Avhole from a side view, with the crescentic interclavicle, forms a rough semi- circle; but the rami are not so evenly curved as in the loons, § which have also a smaller interclavicle. In the loon, in the first stage of Uria,|| and in Hesperornis,^| each ramus is much dilated above ; and this dilatation is formed in a mass of granular tissue, which is almost cartilaginous, and belongs to the acromial or meso-scapular region. The rami of the furcula, like the little bone at their junction (the interclavicle), are parostoses. This median part was not seen by Marsh in Hesperornis.** Anyone who will compare together the figures given in the thirteenth Plate of my work on these parts will see at a glance that the reptile has the raw materials out of which the bird's shoulder-girdle might have been made. Colynibus ; whilst Brandt (op. cit.) calls the loons Eudyptes, and the grebes Podiceps. To mend the matter, the best and latest authorities, the ornithologists of the American Union (The Code of Nomenclature and Check-List of North American Birds: New York, 1886), have for the grebes the generic terms iEehmopliorus, Colymbus, and Podilynibus ; and for the loons Urinator (pp. 73-76). * Op. cit., Plate XVII. , figs. 10-4 ; and Plate VII. of the present Paper. f Shufeldt, op. cit., Part iii., p. 556, fig. 8. J Ibid, § Brandt, Plate XVI.; and Shufeldt, Part ii., Plate IX., figs. 2 and 13. || Op. cit., Plate XVII., fig. 13. ■■ g- h. I. (I.C. i.n.p. io, i.e. i.el. it. i.o.f. i.pa. i.tb. i.tr. J- /. I.e. l.s.v. in. ink. ■in. st. mt.e. ml.t. nix. p. ii. n.px. ob.f. oc.c. od.p. op. o.s. p- pa. p.n.p. pa.s. pb. p. el. pc.p. Fibulare. Foramen magnum. Furcula. Ganglion. Humerus. Horizontal semicircular canal. Intermedium. Interarcticular cartilage. Internal angular process. Intel-centrum. Internal carotid foramen. Interclavicle. Ilium. Inter-orbital fenestra. Inter-palatine. Intermedio-radiale. Ischium. Inferior turbinal. Inter-trabccula. Jugal. Lachrymal Laclrrymal canal. Lumbo-sacral vertebrae. Mouth. Meckel's cartilage. Metasternum. Metacarpal. Metatarsal. Maxillo-palatine, Nasal. Neural arch. Notochord. Nasal floor. Nasal process of pre-maxil- lary. Obturator fenestra. Occipital condyle. Odontoidprocess. Opisthotic. Orbitospbeuoid. Parietal. Palatine. Posterior angular process. Parasphenoid. Pubis. Posterior clinoid process. Postcoraeoid process of ster- ner. p.c.s. p.e. V0- pi i . p. ii. pr.i. pro. pr.z. p.s. p. s.e. pi.,. pt.:. px. 1- aj- r.st. s.og. sc. S.ll. s.i.f. s.o. sp. sp.o. sq. s.r. s.sc. St. st.k. s.r. tb. t.e. te. t.eo. ts. u. ue it. s.r. r. v. a. r.b. Precoracoid. Pre-costal process of ster- num. Perpendicular ethmoid. Pterygoid. Phalanx. Prenasal rostrum. Pre-ilium. Prootic. Pre-zygaphophysis. Presphenoid. Posterior semicircular canal. Post-ilium. Post-zygapophysis. Premaxilla. Quadrate. Quadrato- jugal. Radius. Rostrum of basisphenoid (= rostrum of parasphenoid). Eadiale. Rostral process of sternum. Supra-angulare. Scapula. Septum nasi. Sacro-ischiatic fenestra. Supra-occipital. Splenial. Spbenotic. Squamosal. Sacral rib. Supra-scapula. Sternum. Sternal keel. Sacral vertebra. Tibial. Tendon-canal. Tibiale. Tympanic wing of occipital. Tarsal. Ulna. Ulnare. Uro-sacral vertebra?. Vomer. Vertebral artery. Vestibule. RL. IRISH ACAD CUNNINGHAM MEMOIR:VI. Plate i WKParker del adnal iMP Parker, kth .: an, imp ANATHXE PLATE II. MORPHOLOGY OF THE DUCK AND THE AUK TRIBES. ROYAL HUSH ACADEMY. CUNNINGHAM MEMOIRS, NO. VI. [14] 102 C 'unningharn Memoirs. Fig. 1. 3. EXPLANATION OF PLATE II. Anas hosclias ; 1st stage; left side of pelvis and hinder part of spine, outer view, The same ; 2nd stage ; a similar view of the same parts, .... The same ; 3rd stage ; twelve days' incubation ; a similar view of the same parts, with the pelvis somewhat dislocated from the spinal column, The same ; 5th stage ; eighteen days' incubation ; distal part of left wing, outer view, ........... part uf same object, inner view, ...... part of the same as fig. 4, ...... . 6th stage ; ripe embryo distal part of wing, outer view, part of same preparation, outer view, ..... same object ; inner view, ....... 7th stage ; proximal part of manus, outer view, same object ; inner view, ....... 7th stage ; another specimen ; coccygeal tract of spine ; side 5. The same 6. The same 7. The same 8. The same 9. The same 10. The same 11. The same 12. The same view, Number of times magnified. 16 diameters. 12 diameters. 9-J diameters. 9J diameters. 19 diameters. 29 diameters. 8 diameters. 16 diameters. 16 diameters. 10 diameters. 10 diameters. 5 diameters. 13. CJtauna ehararia ; adult; distal end of ulnar, -with carpals, . . . J Natural size. 14. Cygnus atratus ; part of palate, ........ J Natural size. 15. Anser palustris six 'weeks old ; vomer and antero-superior additional ossicle ; lateral and upper views, 2i diameters. [For List of Abbreviations used on this Plate, vide over.] 104 Cunningham Memoirs. LIST OF ABBEEVIATIONS. [The Roman Numerals indicate Nerves and their Foramina. ,] tic. Acetabulum. fie. Fibulare. per. Precoracoid. ac.p Acromial process of scapula. f.m. Foramen magnum. p.c.s. Pre-costal process of ster- « ti- Angulare. /''■ Furcula. num. ttle. Aliethmoid. 9- Ganglion. p.e. Perpendicular ethmoid. al. it Alinasal. h. Humerus. P'J- Pterygoid. Ul\ Articulare. h.s.c. Horizontal semicircular canal. ph. Phalanx. all. Alisphenoid. i. Intermedium. p. n. Prenasal rostrum. al.sp. Aliseptal. i.ii.c. Interareticular cartilage. pr.i. Pre-ilium. (7.0. Antorbital. i.a.p. Internal angular process. pro. Prootic. a.s.c. Anterior semicircular canal. ic. Intercentrum. pr.z. Tre-zygapliophysis . ut. Atlas. i.e. Internal carotid foramen. p.s. Presphenoid. a.t.r. Anterior tympanic recess. i.cl. Interclavicle. p. .i.e. Posterior semicircular canal tin. Auditory capsule. il. Ilium. pt.i. Post-ilium. ax. Axis. i.o.f. Inter-orbital fenestra. pt.z. Post-zygapophysis. b. It. hi- Basi-liyoliranchial. i.pa. Inter-palatine. px. Premaxilla. ll, h ij . Basihyal. l.r. Intermedio-radiale. ?• Quadrate. bio. Basioccipital. ise. Ischium. <1-J- Quadrato-jugal. b.jy. Basipterygoid. i.tb. Inferior turbinal. r. Radius. l»: Ceratobranchial. i.tr. Inter-trabecula. r.b.i. Rostrum of basisphenoid (= b.s. Basispbenoid. J- Jugal. rostrum of parasphenoid). b.t. Basitemporal. 1. Lachrymal. re. Radialc. c. Centrum and centrale. I.e. Lachrymal canal. r.st. Rostral process of sternum. C.ll. Uncinate process. Ls.v. Lumbo-saoral vertebra;. S.llff. Supra-angulare. Cll.f. Caudal vertebra. in. Mouth. sc. Scapula. c.f.c. Cranio-facial cleft. ink. Meckel's cartilage. S.ll. Septum nasi. c.hij. Cerato-byal. III. St. Metastemum. s.i.f. Sacro-ischiatic fenestra. el. Clavicle. Illt.C. Metacarpal. s.o. Supra-occipital. CO. Columella. mt.t. Metatarsal. sp. Splenial. cp. Carpal. i'i.c./i. Maxillo-palatine. sp.o. Sphenotic. cr. Coracoid and cervical rib. n. Nasal. sip Squamosal. cr.g. Crista galli. ■n. a. Neural arch. l.r. Sacral rib. e.ty. Tympanic cavity. nc. Notochord. s.ie. Supra-scapula. C.ll. Centralo-ulnare. «,/'. Nasal floor. St. Sternum. e.v. Cervical vertebras. n.px. Nasal process of pre-ruaxil- st./t. Sternal keel. ll. Dentary. lary. s.r. Sacral vertebra. d.c. Distal carpal. ob.f. Obturator fenestra. tb. Tibial. thj. Digit. oc.c. Occipital condyle. t.c. Tendon-canal. d.t. Distal tarsal. Oil. p. Odontoidprocess. te. Tibiale. tie. Dorsal rib. op. Opisthotie. t.eo. Tympanic wing of occipital d.s.v. Dorso-sacral vertebras, o.s. Orbitosphenoid. ts. Tarsal. d.v. Dorsal vertebra. p- Parietal. u. Ulna. e.eth. Ectoetbmoid. pa. Palatine. lie. Ulnare. C.ll. External nostril. p. a. p. Posterior angular process. II.S.V. Uro-sacral vertebrae. e.o. Exoccipital. pu.s. Parasphenoid. v. Vomer. En. Eustachian opening. pb. Pubis. v. a. Vertebral artery. /■ Frontal and femur. p.cl. Posterior clinoid process. v.b. Vestibule. fb. Fibula. pep. Postcoracoid process of ster- num. RL. IRISH ACAD CUNNINGHAM MEMOIR: VI . Plate 2. . ker del ad.i^v Id I ■ . ■ ANAT ID At . PLATE III MORPHOLOGY OF THE DUCK AND THE AUK TRIBES. KOTAL IRISH ACADEMY. CUNNINGHAM" MEMOIRS, NO. VI. [^ 5 ] 108 Cunningham Memoirs. LIST OF ABBREVIATIONS. [ The Roman Numerals indicate Jyerces ana t heir J! oramma.J ae. Acetabulum. /be. Fibulare. per. Precoracoid. ac.p. Acromial process of scapula. f.m. Foramen magnum. p.c.s. Pre-costal process of ster- ag. Angulare. />■ Furcula. num. al.e. Aliethmoid. ff- Ganglion. p.e. Perpendicular ethmoid. al.n. Alinasal. h. Humerus. pg- Pterygoid. ar. Articulare. h.s.c. Horizontal semicircular canal. ph. Phalanx. al.s. AlisplrenoiJ. i. Intermedium. p. it. Prenasal rostrum. al.sp. Aliseptal. i.a.c. Interarcticular cartilage. pr.i. Pie-ilium. a.o. Antorbital. i.a.p. Internal angular process. pro. Prootic. a.s.e. Anterior semicircular canal. ic. Intercentrum. pr.z. Tre-zygaphophysis. at. Atlas. i.e. Internal carotid foramen. p.s. Presphenoid. a.t.r. Anterior tympanic recess. i.cl. Interclavicle. p.s.c. Posterior semicircular canal ait. Auditory capsule. il. Ilium. pt.i. Post-ilium. ax. Axis. i.o.f. Inter-orbital fenestra. pt.z. Post-zygapophysis. b.h.hr. Basi-hyobranchial. i.pa. Inter-palatine. px. Premaxilla. h.luj. Basiliyal. i.r. Intermedio-radiale. t. Nasal. so. Squamosal. cr.g. Crista galli. it. a. Neural arch. i.r. Sacral rib. <•■'.'/• Tympanic cavity. nc. Notochord. s.se. Supra-scapula. C.ll. Centralo-uluave. n.f. Nasal floor. St. Sternum. C.V. Cervical vertebra;. n.px. Nasal process of pre-maxil- st./;. Sternal keel. d. Dentary. lary. s.v. Sacral vertebra. i.e. Distal carpal. ob.f. Obturator fenestra. tb. Tibial. dg. Digit. oc.c. Occipital condyle. t.c. Tendon-canal. d.t. Distal tarsal. od.p. Odontoidprocess. te. Tibiale. d.r. Dorsal rib. op. Opisthotic. t.eo. Tympanic wing of occipital d.s.v. Dorso-sacral vertebras, o.s. Orbitosphenoid. ts Tarsal. d.v. Dorsal vertebra. V- Parietal. u. Ulna. e.eth. Ectoetbmoid. pa. Palatine. lie Uluare. e.n External nostril. p.a.p. Posterior angular process. 11. s.v. Uro- sacral vertebra;. e.o. Exoecipital. pa.s. Parasphenoid. v. Yorner. En. Eustachian opening. pb. Pubis. v. a. Vertebral artery. f. Frontal and femur. p.cl. Posterior clinoid process. v.b. Vestibule. fb. Fibula. pep. Postcoracoid process of ster- num. RL. IRISH ACAD. CUNNINGHAM MEMOIR: VI. Plate 3. m WKParW del .ad. nat.MPPii:'li:»:- '.:!_'.. WestJ3ewzna.il imp ' PLATE IV MORPHOLOGY OF THE DUCK AND THE AUK TRIBES. BOYAL IEISH ACADEMY. CUNNINGHAM MEMOIRS, NO. VI. [16] 110 Cunningham Memoirs. EXPLANATION OF PLATE IV. Number of Fig. times magnified. 1. Cygnus nigricollis ; nearly ripe skeleton ; side view, . . . 3 diameters. [For List of Abbbeviations used on this Plate, vide over. J 112 Cunningham Memoirs. LIST OF ABBREVIATIONS. [_The Roman Numerals indicate Nerves and their Foramina.'] ae. Acetabulum. fte. Fibulare. per. Precoracoid. ac.p. Acromial process of scapula. f.m. Foramen magnum. p.c.s. Pre-costal process of ster- ag. Annulare. /''• Furcula. num. al.e. Aliethmoid. 9- Ganglion. p.e. Perpendicular ethmoid. a2.ii. Alinasal. h. Humerus. pg- Pterygoid. ar. Arliculare. h.s.c. Horizontal semicircular canal. ph. Phalanx. al.s. Alisphenoid. i. Intermedium. p. u. Prenasal rostrum. al.sp. Aliseptal. i.n.e. Interarcticular cartilage. pr.i. pre-ilium. a.o. Antorbital. i.a.p. Internal angular process. pro. Prootie. a.s.c. Anterior semicircular canal. ic. Intereentrum. pr.:. Pre-zygaphophysis. at. Atlas. i.e. Internal carotid foramen. p.s. Presphenoid. a.t.r. Anterior tympanic recess. i.cl. Interclaviele. p.S.C. Posterior semicircular canal an. Auditory capsule. it. Ilium. pt.i. Post-ilium. ax. Axis. i.o.f. Inter-orbital fenestra . pt.z. Post-z ygapophysis . li.li.br. Basi-hyobranchial. i.pa. Inter-palatine. px. Premaxilla. h.lnj. Basihyal. i.r. Inl ermedio-radiale. <]■ Quadrate. b.o. Basioccipital. isc. Ischium. IJ-j- Quadrato-jugal. b.pg. Basipterygoid. i.tb. Inferior turbinal. r. Radius. In: Ceratobrancliial. i.tr. Inter-trabecula. r.b.s. Rostrum of basisplienoid (= t.8. Basisplienoid. ./'■ Jugal. rostrum of parasphenoid) . b.t. Basitemporal. 1. Lachrymal, re Radiale. c. Centrum and centrale. I.e. Lachrymal canal. r.st. Rostral process of sternum. C.ll. Uncinate process. I.s.v. Lumbo-sacral vertebra" 1 . s.ng. Supra-angulare. cd.v. Caudal vertebra. in. Mouth. SC. Scapula. city, el. Cranio-facial cleft. ml;. "Meckel's cartilage. s.n. Septum nasi. Cerato-hyal. Clavicle. III. si. Metasternum. s.i.f. Saero-ischiatic fenestra. lllt.C. Metacarpal. s.o. Supra-occipital. CO. Columella. nil.t. Metatarsal. sp. Splenial. ep. Carpal. mx.p. Maxillo-palatine. Sp.O. Spbenotic. cr. Coracoid and cervical rib. it. Nasal. sq. Squamosal. er.g. Crista galli. n.a. Neural arch. s.r. Sacral rib. '•■ ttj. Tympanic cavity. ne. Notochord. s.se. Supra-scapula. C.ll. Ccntralo-ulmire. n.f. Nasal floor. St. Sternum. r.r. Cervical vertebra;. n.px. Nasal process of pre-maxi 1 - St./,. Sternal keel. d. Dentary. lary. s.r. Sacral vertebra. d.c. Distal carpal. ob.f. Obturator fenestra. tb. Tibial. ,hj. d.t. Digit. oc.c. Occipital condyle. t.C. Tendon-canal. Distal tarsal. od.p. Odontoidprocess. te. Tibiale. d.r. Dorsal rib. op. Opisthotic. t.co. Tympanic wing of occipital d.s.v. Dorso-sacral vertebra:, o.s. Orbitospbenoid. ts. Tarsal. d.v. Dorsal vertebra. p- Parietal. 71. Ulna. , jili. Ectoethnioid. pa. Palatine. ne Ulnare. c.ll. External nostril. p.a.p. Posterior angular process. u.s.r. Uro- sacral vertebra:. CO. Exoccipital. pa.s. Parasphenoid. v. Vomer. En. Eustachian opening. P b. Pubis. v.a. Vertebral artery. f. Frontal and femur. p.cl. Posterior clinoid process. v.b. Vestibule. ft. Fibula. pep. Postcoracoid process of ster- num. RL. IRISH ACAD. CUNNINGHAM MEMOIR-. VI .Plate 4. W !v F ■ -,-,- d.l ainat K P Parker kth PLATE V, MORPHOLOGY OF THE DUCK AND THE AUK TRIBES. ri7l ROYAL IRISH ACADEMY. CUNNINGHAM MKMOISS, NO. VI. i_*'J 114 Cunningham Memoirs. Fig 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. EXPLANATION OF PLATE V. Cygnm olor ; («) cygnet 141 inches long ; skull in vertical section The same ; (a) atlas and axis ; side view, . . . . The same ; («■) section of the first three cervical vertebrae, The same ; (5) cygnet 15 inches long; part of atlas ; side view, The same ; (a) centrum of 2.5th part of 24th cervical vertebrae ; horizontal section near lower surface, .... The same ; (b) terminal part of spinal column ; side view Tin same ; same object; lower view, The same ; (a) distal part of wing ; inner view, The same ; («) ankle-joint ; inner view, The same ; same object ; outer view, The same ; same object; front view, The same ; (b) pelvis ; lower view, Chlo'ephaga poliocepJiala, ripe embryo ; distal p The same ; same object ; inner view, The same ; part of fig. 13, lit of wing ; outer view, Number of times magnified. 2 diameters. 3 diameters. 3 diameters. 6 diameters. 3 diameters. 3 diameters. 3 diameters. 3 diameters. 2 diameters. 2 diameters. 2 diameters. 1 1 diameters. 3 diameters. 3 diameters. G diameters. [For List of Abbreviations used on this Plato, vide over.l 116 Cunningham Memoirs. LIST OF ABBEEVIATIONS. [The Roman Numerals indicate Nerves and their Fo, ac. Acetabulum. ae. p. Acromial process of scapula. ag. Angulave. al.c. Alietlimoid. al.ii. Alinasal. nr. Artieulare. al.s. Alisphenoid. al.sp. Aliseptal. a.o. Antorbital. a.s.e. Anterior semicircular canal. at. Atlas. a.t.r. Anterior tympanic recess. an. Auditor}' capsule. ax. Axis. b. lt.br. Basi-hyobranchial. b.luj. Basihyal. b.o. Basioccipital. b.pg. Basipterygoid. br. Ceratobranchial. b.s. Basisphcnoid. h.t. Basitemporal. c. Centrum and centrale. c.a. Uncinate process. cd.v. Caudal vertebra. c.f.c. Crauio-facial cleft. e.Iiij. Cerato-hyal. cl. Clavicle. co. Columella. ep. Carpal. cr. Coracoid and cervical rib. cr.ff. Crista galli. c.tg. Tympanic cavity. at. Centralo-ulnare. (-.!'. Cervical vertebrae. d. Dent uy. d.c. Distal carpal. dg. Digit. d.t. Distal tarsal. d.r. Dorsal rib. d.s.v. Dorso-sacral vertebra;, d.r. Dorsal vertebra. e.eth. Ectoetbmoid. e.n. External nostril. e.o. Exoccipital. En. Eustachian opening. /. Frontal and femur. fb. Fibula. fbc. Fibulare. f.m. Foramen magnum. fr. Furcula. g. Ganglion. h. Humerus. Ji.s.c. Horizontal semicircular canal. i. Intermedium. i.a.e. Interarctieular cartilage. i.a.p. Internal angular process. ic. Intercentrum. i.e. Internal carotid foramen. i.cl. Interelavicle. it. Ilium. i.o.f. Inter-orbital fenestra. i.pa. Inter-palatine. i.r. Intermedio-radiale. isc. Ischium. i.lb. Inferior turbinal. i.tr. Inter-tralieeula. j. Jugal. I. Lachrymal. I.e. Lachrymal canal. l.s.v. Lumho-sacral vertebrae. in. Mouth. ink. Meckel's cartilage. 7ii. sL Metasternum. int.e. Metacarpal. mt.t. Metatarsal. mx.p. Maxillo-palatine. n. Nasal. ii. a. Neural arch. iic. Notocliord. n.f. Nasal floor. n.p.r. Nasal process of pre-maxil- lary. ob.f. Obturator fenestra. oc.c. Occipital condyle. od.p. Odontoidprocess. op. Opisthotic. o.s. Orbitosphenoid. p. Parietal. pa. Palatine. p. a. p. Posterior angular process. pa.s. Parasphenoid. pb. Pubis. p. el. Posterior clinoid process. pep. Posteoracoid process of ster- num. per. p.e.s. p.e. P'J- ph. p. It. pr.i. pro pr.z. p.s. 2).s.e. pl.t. pt.z. p.r. ']■ 'j:i- r. r.b.s. r.st. s.ag. sc. S.ll. s.i.f. s.o. sp. sp.o. sq. s.r. s.se. St. .st. I.'. s.r. lb. t.e. te. t.co. Is. V. ■ne. it. s.r. v. v.a. v.b. Preeoracoid. Pre-costal process of ster- num. Perpendicular ethmoid . Pterygoid. Phalanx. Prenasal rostrum. Pre- ilium. Prootic. Pre-zygaphophysis. Presphenoid. Posterior semicircular canal. Post-ilium. Post -z ygapophysis . Premaxilla. Quadrate. Quadrato-jugal. Radius. Rostrum of basisphenoid (= rostrum of parasphenoid) . Radiale. Rostral process of sternum. S upra-angulare. Scapula . Septum nasi. Sacro-ischiatic fenestra. Supra-occipital. Splenial. Sphenotic. Squamosal. Sacral rib. Supra-scapula. Sternum. Sternal keel. Sacral vertebra. Tibial. Tendon-canal. Tibiale. Tympanic wing of occipital. Tarsal. Ulna. Ulnare. Uro- sacral vertebra?. Vomer. Vertebral artery. Vestibule. RL. IRISH ACAD. CUNNINGHAM MEMOIR: VI. Plate 5. <§a "" @S*W Lit- •->•" i^gr > 1 ft -/? x "-'-'''".'-' W KParker Aelainat .MPEirfcr lltb West.Nrjwinan i-ititj ANATID/E PLAT E VI. MORPHOLOGY OF THE DUCK AND THE AUK TRIBES. ROYAL ntTSH ACADEMY. CUNNINGHAM MEMOIRS, NO. VI. ri8i 118 Cunningham Memoirs. EXPLANATION OF PLATE VI. Fig. 1 Uria troile ; 1 st stage ; embryo, one-third ripe ; skull ; lower view, 2. The same ; mandible of same stage ; inner view, .... 3. The same ; hyoid arch ; upper view, ...... 4. The same ; 2nd stage ; embryo two-thirds ripe ; skull ; lower view, 5. The same ; same skull ; upper view, ...... 6. The same ; mandible of same skull ; inner view, .... 7. The same ; hyoid arch of same skull ; upper view, . 8. The same ; 3rd stage ; embryo, nearly ripe ; section of skull, and innei view of mandible, ••....... Number of times magnified. 6 -} diameters. 6*- diameters. 6-J- diameters. 4 diameters. 4 diameters. 4 diameters. 4 diameters. 4 diameters. [For List of Abbreviations used on this Plate, vide over.] 120 Cunningham Memoirs. LIST OF ABBEEVIATIONS. [The Roman Numerals indicate' Nerves and their Foramina.'] ae. Acetabulum. fie. Fibulare. per. Precoracoid. ac.p. Acromial process of scapula. f.m. Foramen magnum. p.c.s. Pre-costal process of ster- ag. Angulare. fr- Fureula. num. al.e. Aliethmoid. a- Ganglion. p.e. Perpendicular ethmoid. a?. 11. Alinasal. il. Humerus. P9- Pterygoid. ar. Articulare. li.s.c. Horizontal semicircular canal. ph. Phalanx . al.s. Alisphenoid. i. Intermedium. p. ii. Prenasal rostrum. al.s p. Aliseptal. i.a.c. Interarcticular cartilage. pr.i. Pre-ilium. (i.o. Antorbital. i.a.p. Internal angular process. pro. Prootic. a.s.c. Anterior semicircular canal. ie. Intercentrum. pi-.:. Pre-zygaphophysis . at. Atlas. i.e. Internal carotid foramen. p.s. Presphenoid. a.t.e. Anterior tympanic recess. Lei. Interclavicle. p.s.c. Posterior semicircular canal an. Auditory capsule. it. Ilium. pt.i. Post-ilium. ax. Axis. i.o.f. Inter-orbital fenestra. pl.z. Post-zygapophysis. li.h.br. Basi-hyobranchial. i.pn. Inter-palatine. px. Premaxilla. b.hij. Basihyal. i.e. Interuiedio-radiale. g- Quadrate. 1.0. Basioccipital. isc. Ischium. >/:/■ Quadrato- jugal. b.pf/. Basipterygoid. i.tb. Inferior turbinal. r. Radius. br. CeratobranoHal. i.tr. Inter-trabecula. r.i.s. Rostrum of basispbenoid (= b.s. Basispbenoid. J- Jugal. rostrum of parasphenoid). b.t. Basitemporal. I. Lachrymal. re. Radiale. e. Centrum and centrale. I.e. Lachrymal canal. r.st. Rostral process of sternum. c.a. Uncinate process. l.s.v. Lumbo-sacral vertebrae. s.aij. Supra-angulare. ed.v. Caudal vertebra. in. Mouth. sc. Scapula. c.f.c. Cranio-facial cleft. ink. Meckel's cartilage. s.n. Septum nasi. e.liij. Cerato-hyal. m.st. Metasternum. s.i.f. Sacro-ischiatic fenestra. el. Clavicle. int.e. Metacarpal. s.o. Supra-occipital. CO. Columella. mt.t. Metatarsal. sp. Splenial. cp. Carpal. mx.p. Maxillo-palatine. sp.o. Sphenotic. cr. Coracoid and cervical rib. it. Nasal. sq. Squamosal. cr.g. Crista galli. n.a. Neural arch. s.r. Sacral rib. C.tlJ. Tympanic cavity. lie. Notochord. s.se. Supra-scapula. e.n. Centralo-ulnare. ii. f. Nasal floor. St. Sternum. c.v. Cervical vertebra?. n.px. Nasal process of pre-maxil- st.k. Sternal keel. d. Dentary. Distal carpal. lary. s.r. Sacral vertebra. d.c. oh.f. Obturator fenestra. tb. Tibial. dg. d.t. Digit. oe.e. Occipital condyle. t.c. Tendon-canal. Distal tarsal. od.p. Odontoidprocess. te. Tibiale. d.r. Dorsal rib. op. Opisthotic. t.eo. Tympanic wing of occipital d.s.r. Dorso-sacral vertebra?, o.s. Orbitosphenoid. ts Tarsal. d.v. Dorsal vertebra. p- Parietal. it. Ulna. e.eth. Ectoethmoid. pa. Palatine. ue Ulnare. e.n External nostril. p.a.p. Posterior angular process. ii. s.r. Uro-saeral vertebra;. e.o. Exoccipital. pa.s Parasphenoid. v. Vomer. Eu. Eustachian opening. ph. Pubis. v.a Vertebral artery. f. Frontal and femur. p. el Posterior clinoid process. r.b. Vestibule. fl> Fibula. pep. Postcoracoid process of ster- num. RL. IRISH ACAD. CUNNINGHAM MEMOIR: VI. Plate 6 . W K.farkpr del a rj nat "MP.Paxker lith ■.....!■ AL C PLATE VII MORPHOLOGY OF THE DUCK AND THE AUK TRIBES. ROVAL IIUSE ACADEMY. CUNNINGHAM MEMOIRS, NO. VI. [19"! 122 Cunningham Memoirs. EXPLANATION OF PLATE VII. Number of Fig. times magnified. 1 . ~Uria troile ; 2nd stage ; embryo two-thirds ripe ; skeleton ; side view, . 3i diameters. [For List of Abbreviations used o£l tins Plate, vide over.] 124 Cunningham Memoirs. LIST OF ABBREVIATIONS. \The Roman Numerals indicate Nerves and i heir I V am in a. .] flC. Acetabulum. fbe. Fibulare. per. Precoracoid. ni\ p. Acromial process of scapula. f.m. Foramen magnum. p.c.s. Pre-costal process of ster- ag. Annulare. /'■■ Furcula. num. al.e. Aliethmoid. 9- Ganglion. p.e. Perpendicular ethmoid. it Kit. Alinasal. h. Humerus. P!l- Pterygoid. ur. Articulare. h.s.c. Horizontal semicircular canal. ph. Phalanx. aJ.fi. Alisphenoid. i. Intermedium. p. ii. -Prenasal rostrum. ills p. Aliseptal. i.a.c. Interarcticular cartilage. pr.i. Pre-ilium. a.o. Antorbital. i.n.p. Internal angular process. pro. Prootic. il. S.I'. Anterior semicircular canal. ic. Intercenlrum. pr.z. Pre-zygaphophysis. at. Atlas. i.e. Internal carotid foramen. p.s. Presphenoid. n.t.r. Anterior tympanic recess. i.el. Intei'clavicle. p.s.e. Posterior semicircular canal an. Auditory capsule. il. Ilium. pt.i. Post-ilium. ar. Axis. i.o.f. Inter-orbital fenestra. pt.z. Post- z ygapophysis . b.h.br Basi- 1 1 yobranchial . i.pa. Inter-palatine. p.r. Premaxilla. b.hij. Basihyal. i.r. Intermedio-radiale. >!■ Quadrate. b.o. Basioocipital. ise. Ischium. 'J-J- Quadrato-jugal. b.pg. Basipterygoid. i.tb. Inferior turbinal. r. Radius. br. Ceratoliranchial. i.tr. Inter-trabecula. r.b.s. Rostrum of basisphenoid (= b.s. Basisphenoid. J- Jugal. rostrum of parasphenoid). b.t. Basitemporal. 1. Lachrymal, re Radiale. c. Centrum and centrale. I.e. Lachrymal canal. r.st. Rostral process of sternum. at. Uncinate process. l.s.v. Lumbo-sacral vertebrae . s.ag. Supra-angulare. cd.v. Caudal vertebra. in. Mouth. se. Scapula. c.f.o. Cranio-facial cleft. ink. Meckel's cartilage. s.n. Septum nasi. C.lllJ. Cerato-hyal. m.st. Metastermnn. s.i.f. Sacro-ischiatic fenestra. el. Clavicle. Illt.C. Metacarpal. s.o. Supra-occipital. CO. Columella. int. t. Metatarsal. sp. Splenial. ep. Carpal. ni.r.p. Maxillo-palatine. sp.o. Spbenotic. cr. Coracoid and cervical rib. it. Nasal. Sq. Squamosal. ci-.ij. Crista galli. ii.ii. Neural arch. s.r. Sacral rib. e.ty. Tympanic cavity. ■lie. Notocbord. s.se. Supra-scapula. c.u. Centralo-ulnare. ,,./. Nasal floor. St. Sternum. c.v. Cervical vertebra'. n.px. Nasal process of pro-maxil- st.k. Sternal keel. d. Dentary. lary. 8.V. Sacral vertebra. (I.e. Distal carpal. Clb.f. Obturator fenestra. til. Tibial. dg. Digit. oe.e. Occipital condyle. t.e. Tendon-canal. d.t. Distal tarsal. od.p. Odontoidprocess. te. Tibiale. d.r. Dorsal rib. op. Opisthotic, t.eo. Tympanic wing of occipital d.s.v. Dorso-sacral vertebra 1 , o.s. Orbitosphenoid. ts. Tarsal. d.v. Dorsal vertebra. p. Parietal . H. Ulna. e.eth. Eetoethuioid. pa. Palatine. lie. Ulnare. e.ii. External nostril. p.a.p. Posterior angular process. n. s.r. Uro- sacral vertebrae. e.o. Exoccipital. pa.s. Parasphenoid. V, Vomer. En. Eustachian opening. pb. Pubis. r.a. Vertebral artery. /■ Frontal and femur. p.cL Posterior clinoid process. r.b. Vestibule. /*. Fibula. pep. Postcoracoid process of ster- num. RL. IRISH ACAD. CUNNINGHAM MEMOIR: VI. Plate 7 \< - \ . i \ : 1 1 ? \ WK.Pai-kcr d=L ai nat.,M p Parker.lrtli PLATE VIII MORPHOLOGY OF THE DUCK AND THE AUK TRIBES. KOYAL IRTSH ACADEMY. CUNNINGHAM MEMOIRS, NO. VI. [20] 126 Cunn ingham Memoirs. Fig. 1. 2. 3. 4. 5. 0. 7. s. EXPLANATION OF PLATE VIII. Uria troile ; 1st stage; pelvis; lower view, . The same ; 3rd stage ; pelvis ; lower view, The same ; same object ; upper view, The same ; 1st stage ; distal part of leg ; front view The same ; same object ; hind view, The same ; 3rd stage ; part of leg ; front view, The same ; manus of 2nd stage ; inner view, . Part of same ; outer view, .... 9. Cioeronia pusilla ; distal part of wing ; outer view, 10. The same ; distal part of pollex, . 11. The same ; distal part of index, . 12. The same ; proximal part of manus ; inner view, 13. The same ; part of fig. 9, .... Number of times magnified. 7i diameters. 3f diameters. 3|- diameters. 8 diameters. 8 diameters. 3| diameters. 7i diameters. 1 1 diameters. 4i diameters. 13^ diameters. 13i diameters. -i} diameters. 131 diameters. [For List of Abbreviations used on this Plate, ride over.] 128 Cunningham Me mioirs. LIST OF ABBEEVIATIONS. [T/ie Roman Numerals indicate Nerves and their Foramina.'] ac. Acetabulum. ae.p. Acromial process of scapula. at/. Angulare. al.c. Aliethmoid. al.1i. Alinasal. ar. Avticulare. al.s. Alisphenoid. al.sp. Aliseptal. a.o. Antorbital. a.s.c. Anterior semicircular canal. at. Atlas. a.t.r. Anterior tympanic recess. an. Auditory capsule, ax. Axis. b.h.br. Basi-hyoljraiicliial. h.luj. Basihyal. h.o. Basioccipital. li.pi/. Basipterygoid. l/r. Ceratobranchial. b.s. Basispbenoid. b.t. Basitemporal. c. Centrum and centrale. e.a. Uncinate process. cd.c. Caudal vertebra. c.f.e. Cranio-facial cleft. e.lii/. Ccratu-hyal. el. Clavicle. co. Columella. cp. Carpal. cr. Coracoid and cervical rib. c'r.g. Crista galli. c.ty. Tympanic cavity e.n. Centralo-uluare. i.e. Cervical vertebra;. d. Dentary. (I.e. Distal carpal dg. Digit. d.t. Distal tarsal. d.e. Dorsal rib. d.s.v. Dorso-sacral vertebrae, d.v. Dorsal vertebra. e.elh. Ectoetbmoid. e.n. External nostril. e.o. Exoccipital. En. Eustacbian opening. f. Frontal and femur. fb. Fibula. fbe. .'''■■ 9- h. h.s.c. i.n.e. i.a.p. !('. i.e. i.cl. it. i.o.f. i.pa. i.tb. i.tr. J- I. I.e. t.s.i: in. ink. ■in. s(. mt.c. int. I. mx.p. ii. it. a. lie. n.f. ll.p.r. Ob.f. oc.c. od.p. op. o.s. p- pa. p.a.p. pa.s. pb. p.cl. pep. Filmlare. Foramen magnum. Furcula. Ganglion. Humerus. Horizontal semicircular canal. Intermedium . Interareticular cartilage. Internal angular process. Intercentrnm. Internal carotid foramen. Interclaviele. Ilium. Inter-orbital fenestra. Inter-palatine. Internredio-radiale. Ischium. Inferior turbinal. Inter-trabecula. Jugal. Lachrymal. Lachrymal canal. Lumbo-sacral vertebra'. Mouth. Meckel's cartilage Metasternum. Metacarpal. Metatarsal. Maxillo-palatine. Nasal. Neural arch. Notochord. Nasal floor. Nasal process of pre-maxil- lary. Obturator fenestra. Occipital condyle. OJontoiJprocess. Opistliotic. Orbitospheuoid. Parietal. Palatine. Posterior angular process. Parasphenoid. Pubis. Posterior clinoid proi ess. Postcoracoid process of ster- num. per. Precoracoid. p.c.s. Pre-costal process of ster- num. p.e. Perpendicular ethmoid. pg. Pterygoid. ph. Phalanx. p. n. Prenasal rostrum. pe.i. Pre-ilium. pro. Proutic. j»/'.i.-Pre-zygapbopbysis. p.s. Presphenoid. p. s.c. Posterior semicircular canal. pt.i. Post-ilium. pt.z. Post-zygapopbysis. /'.'■. Premaxilla. q. Quadrate. q.j. Quadrato-jugal. /•. Radius. r.b.s. Rostrum of basisphenoid (= rostrum of parasphenoid). re. Radiale. r.st. Rostral process of sternum. s . a ij . S upra-angulare. sc. Scapula. s.u. Septum nasi. s.i.f. Sacro-isehiatic fenestra. s.o. Supra-occipital. sp. Splenial. sp.o. Sphenotic. sq. Squamosal. s.r. Sacral rib. s.sc. Supra-scapula. st. Sternum. st.k. Sternal keel. s.e. Sacral vertebra. ll>. Tibial. I.e. Tendon-canal. te. Tibiale. t.ev. Tympanic wing of occipital. ts. Tarsal. a. Ulna. ue. Ulnare. n. s.e. Uro-sa^ral vertebra:. r. Vomer. v.n. Vertebral artery. v.b. Vestibule. RL. IRISH ACAD. CUNNINGHAM MEMOIR: V!, Plate 8 W.K. Parker, del aAnat.,MP Parker, Lth '■■.'..■ ALCIL<,r, RL. IRISH ACAD. CUNNINGHAM MEMOIR: VI. Plate 9. cLa t J 8 .- eza .. • J c ! - | ||fer v 12 I i - - •ni~. _ I - ■mi ? <•;,._. 13 , 3 14 4 15 ■«* ? -- a •■' x m (V L 1 ' ..1 r \ ... .:..■• ' PLATE IX. MO UP HO LOGY OF THE DUCK AND THE AUK TRIBES. HOITAL IRISH AGADE1I¥. CUNNINGHAM MUMOIRS, NO. VI. [21 | 130 L 'unningham Memoirs. EXPLANATION OF PLATE IX. Fia 1. Aha tor da ; 1st stage ; one-third ripe embryo : distal part of wing ; outer view, 2. The same ; part of same object ; inner view, .... 3. The same ; 2nd stage ; three-quarter ripe embryo distal part of inner view, ......... ■4. The same ; same object; outer view, .... 5. The same ; 3rd stage ; nearly ripe embryo proximal part of maims view, ......•••• 6. The same ; same object ; outer view, ..... 8. The same : 1st stage ; upper part of tarsus ; front view, . 7. Uriatroile; 3rd stage; distal part of wing ; inner view, 9. The same ; 3rd stage ; ankle-joint ; front view, 10. The same ; lower part of same object ; inner view, . 1 1 . The same ; adult ; distal part of pollex, ..... 12. The same ; same skeleton ; distal part of index, 16. \Ga. The same ; head of embryo, one-third ripe ; 1st stage, 17. The same ; do. do. two-thirds ripe ; 2nd stage, 18. The same ; do. do. nearly ripe ; 3rd stage, . 13. Casuarius bennettu ; ripe embryo ; first three vertebras ; upper view, 14. The same ; same object ; lower view, ...... 15. The same ; same object; vertical section, ..... Number of times magnified. 15 diameters. 15 diameters. 6 diameters. 6 diameters. 8 diameters. 8 diameters. 22i diameters. 5 diameters. 3 J diameters. 3f diameters. 2 diameters. 2 diameters. li diameters. Natural size. Natural size. 3 diameters. 3 diameters. 3 diameters. [For List or Abbkeviations used on this Plate, vide oyer. 132 Cunningham Memoirs, LIST OF ABBEEVIATIONS. {The Roman Numerals indicate Nerres and their Foramina.'] ac. Acetabulum. ae.p. Acromial process of scapula. ag. Angulare. al.e. Aliethmoid. al.ii. Alinasal. ar. Articulave. al.s. Alisphenoid. nl up. Aliseptal. a.n. Antorbital. a.s.c. Anterior semicircular canal. at. Atlas. n.t.r. Anterior tympanic recess. an. Auditory capsule. fix. Axis. b.h. In: Basi-li y obranchial . b.luj. Basihyal. b.o. Basioccipital. b.pg. Basipterygoid. br. Ceratobranchial. b.s. Basispbenoid. b.t. Basitemporal. c. Centrum and centrale. at. Uncinate process. cd.v. Caudal vertebra. c./.c. Cranio-facial cleft. e.lnj. Cerato-byal. cl. Clavicle. eo. Columella. ep. Carpal. er. Coracoid and cervical rib. or.g. Crista galli. c.ty. Tympanic cavity. c.n. Centralo-ulnare. c.v. Cervical vertebree. d. Dentary. (I.e. Distal carpal. dg. Digit. d.t. Distal tarsal. d.r. Dorsal rib. d.s.r. Dorso-sacral vertebras, d.r. Dorsal vertebra. e.eth. Ectoetbmoid. e.n. External nostril. e.o. Exoccipital. Eu. Eustachian opening. f. Frontal and femur. fb. Fibula. fbc. Fibulare. f.m. Foramen magnum. fe. Furcula. g. Ganglion. it. Humerus. h.s.c. Horizontal semicircular canal. i. Intermedium. i.a.e. Interarcticular cartilage. i.ii.p. Internal angular process. ic. Intercentrum. i.e. Internal carotid foramen. i.cl. Interclavicle. it. Ilium. i.o.f. Inter-orbital fenestra. i.pa. Inter-palatine. i.e. Intermedio-radiale. ise. Ischium. i.tb. Inferior turbinal. i.tr. Inter-trabecula. j. Jugal. /. Lachrymal. I.e. Lachrymal canal. l.s.v. Lumbo-sacral vertebra;. in. Mouth. ink. Meckel's cartilage. in. st. Metasternum. mt.e. Metacarpal. int.t. Metatarsal. in.c.p. Maxillo-palatine. a. Xasal. ii.ii. Neural arch. ne. Notochord. ii.f. Nasal floor. n.p.r. Nasal process of pre-maxil- lary. ob.f. Obturator fenestra. oc.c. Occipital condyle. u'/./i. Odontoidprocess. up. Opisthotic. o.s. Orbitosphenoid. p. Parietal. pa. Palatine. p. a. p. Posterior angular process. pa.s. Parasphenoid. ph. Pubis. p. el. Posterior clinoid process. pe.p. Postcoracoid process of ster- num. per. Precoracoid. p.c.s. Pre-costal process of stei num. p.e. Perpendicular ethmoid. pg- Pterygoid. ph. Phalanx. p.n. Prenasal rostrum. pr.i. Pre-ilium. pro. "Proutic. pr.z. Pre-zygaphophysis. p.s. Prespbenoid. p.s.e. pt.i. pl.z. p.v. 1- q.j. r. r.b.s. r.st. s.aff. se. s.n. s.i.f. s.o. sp. sp.o. sq. s.r. s.sc. St. st.k. s.v. tb. I.e. te. Leo. ts. ll. e.a. e.b. Posterior semicircular canal. Post-ilium. Post-zygapophysis. I'remaxilla. Quadrate. Quadrato-jugal. Radius. Postrum of basisphenoid (= rostrum of parasphenoid). Radiale. Rostral process of sternum. Supra-angulare. Scapula. Septum nasi. Saero-ischiatic fenestra. Supra-occipital. Splenial. Spbenotic. Squamosal. Sacral rib. Supra-scapula. Sternum. Sternal keel. Sacral vertebra. Tibial. Tendon-canal. Tibiale. Tympanic wing of occipital. Tarsal. Ulna. Ulnare. Uro-sacral vertebra;. Vomer. Vertebral artery Vestibule. NOVEMBER, 1890.] ROYAL IRISH ACADEMY. «n CUNNINGHAM MEMOIRS. >J No. VI. ON THE MORPHOLOGY OF THE DUCK AND THE AUK TRIBES. BY W. KITCHEN PARKER, F.R.S. mm Mint llai.es. 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