Mddddildddddiddéddddddddsiididdidliididididididdiidilidsldidiisdsdiés WYO Yi be Yy yy Gy =U Yj Di yyy g Yj Yj YHy \\ NAAN Ne \\ \ ; . ‘ \ | A \ \x WY ee Pith wae YO N hitet eC Wei sK h iN Tah Ne wth Lael» 1 1s u ry if 1 UHURU entay Paint Wir ee ay PTR Ate i) iit re AY ft " : n ta ian eas i i 6! wh fay ie ra Chaat ATAU ANY bey if We AeA A ini 4 ; i te i o ay Lary , Devil ye tri i wy Lh i ae Ay ¥ : P eRe HORAN KN pha bE Pee ie ; 5 AN ak 5) ‘ A) ’ Lae, i f i) Pad, Ae tee i ‘nD Sit bey AVA Al 1 OS. TELS EWNRT AY ye ONT ARUG HYD A athe ty FYE My Aki Ne Hy iH j vik vi Ne \ Mi oy AG PAA Wa LA pan { Leg 1G Uinta Yat ree e Le MN eG WITH THE AUTHORS COMPLIMENTS. Education Department Bulletin Published fortnightly by the University of the State of New York Entered as second-class matter June 24, 1908, at the Post Office at Albany, N. Y., under the act of July 16, 1894 No. 447 ATE BAINYS EN Ye May 15, 1909 New York State Museum Joun M. Crarke, Director JEANS {7 . } Museum bulletin 130 ( , an Cy \ oO r OSTEOLOGY OF BIRDS BY R. W. SHUFELDT E PNGCUP LIES to) 0c evenoioye wi ales eel o> 00. 862 5 | Anseres (continued) ipretaGeyran DRE OTC aE 5 PXMatiniaGreame mise b sore ces Oe 270 dintroditetre mn ae cep 2 encletes 7 Modification of uns larynx and Garivartidaes sres.catiec.. sec oe 10 tracheal we ne smear. c om ee ads 207 alco midace. crcetyesevaie tiene 52 Appendicular skeleton......... 301 Osteological characters synop- ANCONA. Soodn ocoda OAD e 306 ticallyrarranged)..4 4.) ceee eee 125 Trunk skeleton of the Anserinae 315 RNelationsitipSesecmm en sake anos 133 Gyominae pn tain. s Hossein 330 PNG ETAICSS rove 3c at tote nie cost alien 133 Notes on fossil Anseres....... 335 Explanation on platesuemece 137 Remarks on the classification Gallia ern ne cat tattoos cates ne 169 of the North American An- Gallltissbanciveleeteserect. tee 173 SERCO Me Ta says fale an ttereveheraie ars 4 338 Analyticalysumimartyns ste. «ole 222 PNGtA TALES cepa ercremes © cievess whe acetone 339 INGIEIHOMAIMPSs cbobscenassones Lay Explanation of plates.......... 341 UNCden Gan ari o:5 seealewcle! crs) Pewnan 225) \"iCoccystes plandanius.....,.....- 345 Explanation of plates.......... 223 eB ibliographuyspecme ss sc. ce-scde « « 357 IMDSERES SIRs Woe ee eae 2AO Rm Mlindexcaeeria cian stole te sais ke ree ace 300 ALBANY UNIVERSITY OF THE STATE OF NEW YORK 1909 M206r-N8-1500 I9t3 1917 IgIg 1914 Igt2 1918 Ig1O Igt5 Igit 1920 1916 1g2I STATE OF NEW YORK EDUCATION DEPARTMENT Regents of the University With years when terms expire Wuiretaw Reip M.A. LL.D. D.C.L. Chancellor Sr Crarr McKetway M.A. LL.D. Vice Chancellor DANIEL BEACH Ph.D? LED, 3 -e Pruay T. Sexron LLB AG T. Guitrorp SmitH M.A. C.E. LL.D. =F ihe Wittiam NortincHam M.A. Ph.D. LL.D. - CHESTER S:. LORD McA. LIED: sey Poa ALBERT VANDER VEER M.D. M.A. Ph.D. Epwarp LauTrerBacH M.A. LL.D. - - - EuGENE A. PHILBIN LL.B. LL.D. ra el Eucian LL. SHEDDEN 2B. a Ee - - - Francis M. CARPENTER ey Gee - = Commissioner of Education ANDREW S. DRAPER LL.B. LL.D. Assistant Commissioners New York Brooklyn Watkins Palmyra Buffalo Syracuse New York Albany New York New York Plattsburg Mount Kisco Aucustus S. Downinc M.A. Pd.D. LL.D. First Assistant FRANK Rouuins B.A. Ph.D. Second Assistant THomas E. FINEGAN M.A. Zhird Assistant Director of State Library James I. Wver, Jr, M.L.S. Director of Science and State Museum Joun M. CrarkeE Ph.D. LL.D. Chiefs of Divisions Administration, HARLAN H Horner B.A. Attendance, JAMES D. SULLIVAN Educational Extension, WiLLIamM R. Eastman M.A. M.L.S. Examinations, CHARLES F. WHEELOCK B.S. LL.D. Inspections, FRANK H. Woop M.A. Law, Frank B. GivBertT B.A. School Libraries, CHaries E. Fitcu L.H.D. Statistics, Hiram C. CASE Trades Schools, ARTHUR D. DEAN B.S. Visual Instruction, ALFRED W. Aprams Ph.B. New York State Education Department Science Division, November 2, 1908 Hon. Andrew S. Draper LL. D. Commissioner of Education Sir: I have the honor to transmit herewith a series of papers re- latine to the ostelogy of birds by R. W. Shufeldt M. D. of New York. . Dr Shufeldt’s eminent standing as a comparative anatomist, his generosity in donating to the State Museum his very valuable col- lection of bird skeletons and the appositeness of these papers to other studies of the New York birds now in course of publication by us justify the printing of these contributions as a bulletin of the State Museum and I so recommend. Very respectfully yours Joun M. CLARKE Director State of New York Education Department COMMISSIONER'S ROOM Approved for publication this 5th day of November 1908 ) 2a Commissioner of Education Education Department Bulletin Published fortnightly by the University of the State of New York Entered as second-class matter June 24, 1908, at the Post Office at Albany, N. Y., under the act of July 16, 1894 No. 447 ALBANY, N. Y. MAY 15, 1909 New York State Museum JouN M. Crarke, Director Museum bulletin 130 OSTEOLOGY OF BIRDS BY > R. W. SHUFELDT M.D. OSTEOLOGY OR THE yACCIPItTRES PREFACE In years gone by I find I have published a number of illustrated notes, papers and one or two more or less extensive memoirs on - the raptorial birds, the Old World vultures and the American Cathartidae. Nearly all of these were of an osteological character, and will be utilized or more or less incorporated into the present work. In doing this a few of my former figures will be reproduced, but beyond this all the text cuts illustrating the present treatise are entirely new, and have not heretofore been published anywhere, and this is the case with all of the figures upon the plates. My earliest osteological paper upon this group of birds was pub- lished in October 1881, and was entitled On the Ossicle of the Anti- brachium as Found in Some of the North American Falconidae [Nutt. Ornith. Club Bul. p. 197-203]. In January 1886 I gave a brief paper On the Free Post-pubis in Certain of the Falconidae [The Auk, v. 3, no. I, p. 133-34]. Both articles were illustrated. Three years thereafter, or in April 1880, I published an illustrated account of the Osteology of Circus hudsonius [Jour. Comp. Med. & Surg. v. 10, no. 2, art. 10, p. 126-59], and this paper with the figures to it, thoroughly revised, is incorporated into the present bulletin. In October 1892 I described some extinct birds of the 5 6 NEW YORK STATE MUSEUM group here being considered in a contribution entitled 4 study of the Fossil Avifauna of the Equus Beds of the Oregon Desert [Acad. Nat. Sci. Phila..Jour. v. 9, pl. 15-17, p. 389-425]. A year previous to this, however, appeared my paper on Some Comparative Osteological Notes on the North American Kites |The Ibis, Lond. Apr. 1891. v. 3, no. 10, p. 228-32], and the same month a brief note in The Auk on A Peculiar Character Referable to the Base of the Skull in Pandion [v. 8, no. 2, p. 236-37]. Another character in the skeleton of the Osprey was also noticed in an article published in The Ibis in July 1894, entitled On Cases of Complete Fibulae in Existing Birds’ [Lond. v. 6, no. 23, p..301-66]. Duringsthe next following three years I printed two or three other papers on the Falconidae, but none of these had anything to do with the osteology of the family. By far the most extensive memoir on the subject however and the last one preceding what is herein set forth, ap- peared in its revised form in the r2th Annual Report of the United States Geological and Geographical Survey of the Territories [Wash. Oct. 14, 1882, p. 727-88, pl. 15-24]. In the text of this treatise the osteology of the Cathartidae is very fully described, and illustrated by a few outline text cuts, while on the plates are 24 lithographic figures (natural size) giving the skulls (various views) and other bones of nearly all the American Cathartidae, including the condor, the Californian condor, the King vulture, Turkey buz- zard, and the Black vulture. The text of this memoir is incor- porated in the present work but is presented in an entirely new form, thoroughly revised, amplified and improved. None of the plate figures have been used again, though some of the same speci- mens have been taken from a different point of view, and these may be advantageously compared with those already published in the 12th Annual Report above cited. - Washington, D. C., January 31, 1901 INTRODUCTION Many ornithotomists contend that the Striges properly belong in the group to be dealt with in the present treatise. My staunch imeem tne late: Prot. VW. Kk. Warker FP: Ro Se thought so, and there are undoubtedly others who hold the same _ opinion. Huxley made his division of the Aetomorphae equivalent to the “Raptores”’ of Cuvier, and considered that they constituted four natural groups—the Strigidae, the Cathartidae, the Gypaetidae, and the Gypogeranidae [Zool. Soc. Lond. Proc. 1867, p. 462], but since the appearance of his famous contribution to the subject, the belief has been growing more general that the Striges have no place there, that the Old World vultures hardly more than constitute “a subfamily” apart from the Falconidae, and that, finally, the Cathartidae or our New World vultures are also a family of the Accipitres proper, and not very nearly connected with the Vulturidae * of the Old World. With respect to the Cathartidae, Dr Elliott Coues has said that “In a certain sense, they represent the gallinaceous type of struc- ture; our species of Cathartes, for instance, bears a curious super- ficial resemblance to a turkey” [Key. rev. ed. p. 557]. In such classification I can in no way agree; it is nearly as bad as that of Garrod who placed these New World vultures among the storks and herons [Coll. Sci. Mem. p. 215]. The more likely relation- ships are well expressed by Newton who has remarked in his article Ormthology |[Encylo. Brit. ed. 9, 18:47], that “ whatever be the alliances of the genealogy of the Accipitres, the diurnal birds of prey, their main body must stand alone, hardly divisible into more than two principal groups — (1) containing the Cathartidae or the vultures of the New World, and (2) all the rest, though no doubt the latter may be easily subdivided into at least two families, Vul- turidae and Falconidae, and the last into many smaller sections, as has commonly been done; but then we have the outliers left. The African Serpentaridae, though represented only by a single species, are fully allowed to forma type equivalent to the true Accipitres com- posing the main body; but whether to the Secretary-bird should be added-the often-named Cariama, with its two species, must still re- main an open question.” 8 NEW YORK STATE MUSEUM Furbringer entertains practically the same opinion when he makes his suborder, the Ciconiiformes, of the order Pelargornithes contain, among others, the “ Gens” Accipitres, which last is divided into the four families Gypogeranidae, Cathartidae, and the Gypo-Falconidae. This arrangement also, is probably very near the true statement of the several affinities of these groups of birds. How interesting it would be, were it possible to trace back through the geological record the several tribes of birds now represented by the Accipitres, the parrots, owls, and Caprimulgi. In the classification adopted in the present work, the suborder Accipitres, here to be considered, will be primarily divided into two superfamilies, viz: the Cathartoidea, and the Falconoidea — the first to contain all the New World vultures under the family Cathartidae, the latter all the Old World vutures (Vulturidae), and the entire assemblage of “diurnal Raptores.” These last may be divided into two families, viz: the Falconidae, and the Pandionidae. The Falconidae will be made to contain all the falcons, kites, eagles, hawks, Old World vultures and Secretary-bird, while the last named family will contain Pandion alone. In the course of the present treatise some few references will be made to the osteology of the Condor, while for the osteology of our own vultures, Gymnogyps californianus, Cathar-~ tes a, septentrionalirs and -Catharista —wnmpe I will introduce, as I have already said in the preface, a revision of my former work upon the Osteology of the Cathartidae, pub- lished several years ago in the 12th Annual Report of Hayden's Survey. Our United States Falconidae, consist then, first, of four genera of kites, each represented by but a single species. (I regret to say that I have at present no skeleton of Rostrhamus.) Elanoides forficatus Ictinia mississippiensis Elanus leucurus Rostrhamus sociabilis For the loan of 63 skeletons illustrating the osteology of the Accipitres, I am indebted to the United States National Museum, to its distinguished secretary the late Prof. G. Brown Goode, and to Mr Lucas. .For excellent skeletons of Elanoides and Ictinia as well as other Falconidae, I am greatly indebted to Mr J. A. Singley of Giddings, Tex. . | OSTEOLOGY OF BIRDS 9 The next genus Circus is also represented by but one species in this country, and I have already published an account of its oste- ology in the New York Journal of Comparative Medicine and Sur- gery, for April 1889. It will be incorporated here: Circus hudsonius There are many skeletons in my private cabinet of this well known harrier. Our genera Accipiter and Astur have four species known to orni- thologists, viz: Accipiter velox Astur atricapillus Accipiter cooperi Astur atricapillus striatulus Skeletons of several of them are to be found in my material, and Dr W. S. Strode of Bernadotte, Ill., has kindly favored me with others, to be used in the present connection, and for similar favors I am indebted to Mr T. D. A. Cockerell. The genus Parabuteo has but the species Parabuteo unicinctus harrisi Rosse Harriss hawk alco “harris: of Audubon, andi regret to say that I have not examined its skeleton. Of our long list of species representing the genus Buteo, some 13 species, I have studied only a few representative ones, as Buteo Bim atic te Oo wb,Oc-e-a, li-sy Cal rw s,.-and parts of skeletons of others. ; ' Urubitinga has but the one species in otir avifauna, the Mexican black hawk, Urubitinga anthracina, and I have investigated its skeletal structure StL Ne Asturina also has but the species Asturina plagiata, and Mr Herbert Brown of Tucson, Ariz., has kindly supplied me with skeletons of this Mexican goshawk. ; The “ Rough-legged hawks” of the genus Archibuteo, have three Species, viz: Archibuteo lagopus Archibuteo ferrugineus Archibuteo lagopus sancti-johannis IO NEW YORK STATE MUSEUM The osteology of all of them has been studied by me, from abundance of material. The first named has recently been elimi- nated from our avifauna. Coming next to the eagles — our avifauna offers the following genera and species, viz: Aquila chrysaétos Haliaetus albicilla Thrasaétus harpyia Haliaétus leucocephalus, and of them I have seen skeletons of Haliatus leucoce- phalus, and Aquila chrysaétos and some joncian forms. There has recently been’ added to our list Hy loalase Gata tsy. Some 14 or 15 species of the genus Falco are represented in the avifauna of this country, and | have been permitted to examine skeletons of a number of them, as for instance — Falco island- us, Falco columbarius;. .Palco omexicgaosu Falco sparverius, Palco-rwsticolusiey G falco. and others. Of the caracaras we ‘have Polyborus cheriway Polyborus lutosus and I see on the list of my material from the United States National Museum, Polyborus tharus, Polyborug ane@u- boni, which will probably answer for the skeletal characters of these birds. I am also indebted to Mr Lucas for a complete skeleton, Polyborus lutosus, loaned from his private cabinet. Ospreys complete our Falconidae, and we have the well known cosmopolitan type Pandion haliaétus carolinensis. The museum skeleton has been seen by me, and Mr Philip Laurent of Philadelphia has kindly sent me a complete one of his own col- lecting. Its osteology is especially interesting. Skeletons of foreign hawks, kites, eagles ete. have also been studied in connection with the preparation of the present treatise, as Geranospizias mniger,* Herpetotheres, (Na stseepa. color, Ibycter, Micrastur, Milvago, Rupornis, Gypogeranus, and a number of others. CATHARTIDAE Great pneumaticity characterizes nearly all the bones of the skeleton of any one of the species of this family, and it is only cer- tain portions of the cranium, lower maxilla and pelvis, the hyoidean arches, the atlas, the tail vertebrae, the bones of the pelvic limb OSTEOLOGY OF BIRDS il below the femur, and all the sesamoids and ossifications pertaining to the sense organs, that appear to be exempt from the condition. Where its exists it is very perfect and gives an unusual lightness to the skeleton of one of these birds— forms so constantly on the wing, and such masters of the faculty of flight. Notwithstanding all this, the several bones of these vulturine types are large, that is in bulk and caliber, while the long bones of the wings are of more than average length for the size of the species possessing them. Skull. Among the most of our Cathartidae the birds are nearly a year old before several of the cranial sutures have become absorbed, such as the frontonasal sutures, the various sutures of the lacrymal, and others. These are all more than usually well obliterated, and led Huxley to say of Cathartes a. septentrionalis that the “lacrymal bones are so completely anchylosed with the frontals and with the broad prefrontal processes, that all traces of their primitive distinctness are completely lost.” [Zool. Soc. Lond. Proc. 1867, p. 463] In a specimen of this species of the first summer, | find the great nasal bones largely overlap the frontals, being well separated from each other in the middle line. The craniofacial hinge is quite free, and an interesting supplementary hinge is formed between the superoanterior border of either lacrymal, and the mar- gin of the nasal opposite it. A small foramen is left at this point in Cathartes a. septentrionalis, into which the nasal glides when the superior mandible is depressed [pl. 6, fig. 9]. Practically, the same condition exists in Catharista uru bu, where the nasal process becomes peglike, and really articulates in a socket on the interior aspect of the lacrymal. This character is least marked in the condor (Sarcorhamphus), though in our Gymnogyps the nasal process of this peculiar joint is much longer, curved up- ward, and glides over a greater surface on the lacrymal.* [See Pe) ht 1243) 1 This mobility of the craniofacial hinge in Cathartes a. septentrion- alis is responsible for a condition of separation at the pterygobasisphenoidal articula- tions, for we have observed in nearly all of the dry skulls of the Cathartidae that the pteryapophysial processes of the basisphenoid never meet the facets on the pterygoids that are evidently intended for their articulation. This seems to be due to a warping upward of the superior mandible during the process of drying, drawing both the pala- tines and with them the pterygoids away from these pteryapophyses. If we take the pains, however, to dissect the head of a recently killed vulture, as the writer has done, we will at once appreciate the normal state of affairs, and find that by the slightest pressure downward of the upper bill the facets upon the ‘pterygoids glide over the pteryapophyses. We will find many of the illustrations representing them in published works of other authors, with the interspace between. Our own figures illustrating pre- vious memoirs do so, and Professor Huxley has done so before us, although he says of Cathartes a. septentrionalis “The basipterygoid processes are large and articulate with the pterygoids.” [Zool.. Soc. Lond. Proc. 1867. p. 440, fig. 22] 12 , NEW YORK STATE MUSEUM Returning for a moment to the craniofacial joint we find in all of our vultures the sutural traces of the nasal processes of the pre- maxillary persisting through life, the ethmoid being exposed in young birds, but gradually becomes hidden as age advances. In this internasal region the surface is concaved, the depression being shallow and broad in Gymnogyps. and Cathartes — deeper and more decided in Catharista and the condor. From this concavity, the upper and convex surface of the nasals, and the rather wide premaxillary, the osseous culmen starts broad and spreading — to rapidly contract again between the capacious nostrils, then suddenly fall, roundly convex to the tip of the beak, after first passing over a rise that occurs with greater or less abruptness just in front of the anterior margins of the peripheries of the nostrils. This is best seen in Sarcorhamphus and less decided in Gymnogyps than any of the others. It is really the upper culminal depression that per- sists down the side of the bill to cause the “swell” at its extremity in the condor and carrion crow. The osseous tomia of the superior mandible are sharp from a point taken below the center of the nostril, forward to the tip of the beak, the line being doubly curved as the beak is so powerfully hooked at its extremity. A row of nutrient foramina are found at a greater or less distance above this margin in all the Cathartidae, with numerous other smaller ones scattered about above them, which exhibit no regularity in their arrangement. Venations caused by the vessels running into them are permanently impressed upon the bone. The external osseous narial apertures in these birds are very large, being placed upon the sides of the superior mandible. In form they assume more or less of an oval outline, being long and narrow in Catharista urubu, high and broad in the Cali- fornian vulture and the Turkey buzzard. Our figures of the skulls of the Cathartidae in the present treatise will show the forms of these apertures, and give an idea of their shape better than any description can do [see pl. 2, fig. 2, 3; and pl. 6, fig. 9]. Beneath, the superior osseous beak is much concaved in all these birds, while the entire rhinal space, above, presents but few ossifica- tions. There is no osseous septum narium at all, anteriorly, and it is only above the maxillopalatines that a narrow, horizontal, bony shelf is seen, that is connected with the roof by a meager, median, bony septum. Mesially, this ossification throws out a process in front (Cathartes a. septemtr toe mashes) whichscunl seep in Gymnogyps, and the vertical plate, to which reference has OSTEOLOGY OF BIRDS 13 just been made, extends backward to meet the ethmoid in Ca- (ivanes: aose pbhentraotalrs andyCatharista urubu, and in all the species spreads out more or less laterally, thus forming a strong abutment superiorly, while it divides the space into two, so that they appear like true longitudinal bony nostrils within. In all the vultures examined, with the exception of Gymnogyps, a pit is seen to exist upon the inferior aspect of the horizontal partition, in the middle line, it having almost the appear- ance of a pneumatc foramen to supply this part of the skull. _ All of the Cathartidae have skulls of a characteristic appearance when viewed upon superior aspect. Old birds, as a rule, exhibit a transverse though moderate mounding of the frontal region im- mediately posterior to the craniofacial depression, and posterior to this the interorbital area is very broad. The cranium in the parietal region, and all down at the sides is regularly rounded and smooth. It presents evidence of a good brain case within. The surface ex- hibits, further, many osseous venations, the majority of which run to the foramina that exist in an irregular double row, removed by a few millimeters from the orbital peripheries. These foramina lay along in a shallow groove in these localities. From them the bony and sharp edged brows overhang the orbital cavities which are rendered especially deep by such beetling eaves. Age has every- thing to do with the extent to which the frontal bones thus extend out laterally and overarch the orbits above. Specimens of young and adult GCathartes a. septentrionaltis demonstrate this most conclusively, and as another good instance I have two crania of Gymnogyps before me; in one, the superior orbital peri- pheries are jagged and thin, coming very close to the foramina men- tioned in the last paragraph, being only a little over two centimeters © apart, measured at the narrowest point transversely across the frontal region. In the other specimen; and evidently a very old bird, they are rounded and arched over the orbits, upon either side, thick and heavy, their rims being nearly five centimeters apart, all of which lends this skull a far more raptorial aspect than is enjoyed by the skull of the younger specimen [see pl. 2, fig. 2]. Most prominent among the features at the lateral aspect of the skull of these vultures of ours, is the large Jacrymal bone already alluded to in part. We have sufficiently pointed out how its anterior border above articulates in a peculiar manner with the nasal, and ‘how the bone fuses with the frontal. Now below this, upon its lateral aspect is a longitudinal groove, and still inferior to this again, the main descending portion of the bone. This, in old specimens of 14, NEW YORK STATE MUSEUM Cathartes a. septentrionalis, completely coossifies with the lower external half of the pars plana, but does not quite come in contact with the maxillary bar. Essentially, Catharista urubu agrees with this, but this portion inSarcorhamphus gryphus and Gymnogyps californianus often knitting as usual with the ethmoidal wing, is produced downward, backward and outward, asa clublike process to almost reach the zygoma. In. such ‘a form~as . Neo ph ton + preremio pisess tsmaroe ar- rangement leans more toward the Falconidae than toward the Cathartidae, though there is a positive step vultureward. In this bird the superciliary portion has shrunk in size, articulates prin- cipally with the margin of the nasal, while the body of the bone, below, engages the entire border of the pars plana, and all the sutural traces are usually permanent throughout the life of the in- dividual [pl. 6, fig. ro]. As we pass falconward, the next interesting step is seen in the lacrymal as it occurs in Gy pogeranus: Ser p eat ction where the superciliary part forms much the larger share of the entire bone, while the body becomes a mere inbent osseous bar that touches the pars plana at the angle. Here the inner margin of the upper or superciliary portion meets the nasal and frontal bones for its entire length; the articulation being very close, but the suture plainly visible. When we come to the Falconidae, a great number of interesting forms of the lacrymal will be met with, and it will be seen to present characters of excellent classificatory importance. Among the vultures the lacrymal is pneumatic. This is likewise the case with the large, quadrate pars plana, which in Cathartes shows a con- siderable excavation upon its anterior aspect. Above this inter- orbitorhinal partition a large vacuity exists [sce pl. 6, fig. 9]. As for the mesethmoid it meets the vault of the rhinal space above in a spreading abutment; from this point it takes a direction’ downward and backward in the mesial plane, to become con- solidated with the extremity of the basipresphenoid, below. Be- hind, by the extension of its median osseous plate, it assists to com- plete the orbital septum. This latter is quite entire in adult speci+ mens of Cathartes a. sept enti oats sands Grane nee rista urubu, while in Gyparchus, the condors and others a vacuity is always seen to exist near its middle [see Hayden's 12th An. Rep t,.pl2ievic ere: OSTEOLOGY OF BIRDS I5 InCathante’s a.sepitentrionalis the pars plana, upon either side, is situated considerably behind the forepart of the mesethmoid, the anterior margin of which latter is sharpened and slopes from above, downward and backward. Still confining our attention to the lateral aspect of the skull, it is to be observed that the temporal fossa is much restricted and rather shallow, while the sphenotic and squamosal processes are moderately developed and of about equal length. The zygoma is a stout bar of bone, showing but faintly the sutural traces among its original elements. Between quadrate and pars plana it is quite straight; it is then bent slightly downward to pass forward to the denary process of the premaxillary. At its proxi- mal end a peglike process, placed at right angles to the continuity of the bone, is intended for articulation with a corresponding socket on the outer side of the quadrate [pl. 6, fig. 9]. Another notable feature upon this aspect of the skull is the great, gaping aperture to the internal ear; indeed, so exposed is this in the dried cranium, that the surrounding osseous walls offer no impedi- menta to our looking through the short Eustachian tube, or even into the semicircular canals. Passing next to the base of the skull in the Cathartidae, we find the foramen magnum subcircular in outline and moderately large. The condyle is usually very well developed, and distinctly notched in the middle line upon its upper surface. The lower arcs of the bony rims of the external aural openings are produced downward below the general surface, upon either side, and we are to observe that the basitemporal area is very distinctly defined, being triangular in outline and usually small. Its angle in front underlaps the large, single anterior aperture to the Eustachian tubes, while the lateral angles are frequently drawn downward as prominent processes. These latter are markedly conspicuous in such forms as the condors, Gymnosy ps ands (Cathartes a..iseptentrionalis, while in Catharista they are merely low ridges of no particular note. Often in the skulls of subadult specimens of Cathartes a. -septentrionalis we find the Eustachian tubes unprotected by bone in front, the passage being an open, gaping gutter, upon either side, extending from the ear to the base of the rostrum. Birds of several years of age may exhibit this feature in Cathartes, and it probably obtains in the condors. Inferiorly, the sphenoidal rostrum is rounded and rather broad at its base, but as we follow it forward, it is seen to gradually taper 16 NEW YORK STATE MUSEUM to a sharpened apex, which, in Cathartes a. septentrion- alis protrudes under the mesethmoid in front, where it takes the place of a vomer, that bone being apparently absent in all of our Cathartidae, except perhaps in Gyparchus. The palatines are broad plates of bone, with a wide, median fissure separating them for their anterior two thirds; in front their pointed ends are, upon either side, wedged and anchylosed in be- tween the dentary process of the premaxillary below, the maxillary and nasal above and to their outer aspects. These “ prepalatine” portions of the palatines are nearly horizontally disposed, but as we follow the bones backward, we find their internal and ex- ternal margins deflected downward, more especially the internal ones; and the bones here are in mutual contact for some consider- able distance in the median plane. These “ postpalatine” portions thus articulating, offer above a longitudinal, subcylindrical gutter, which is molded upon the nether side of the rostrum, over which it glides, whenever the superior mandible is depressed. The pterygoid extremities of the palatines are ample and offer in each case a good sized facet for articulation with the anterior end of the corresponding pterygoid. In all of our species of the Cathartidae the “ posteroexternal angles ” of the palatines are rounded off, and upon the whole these bones are much the broadest in Gyparchus papa, and narrowest in Catharista urubwu [see Hay- den’s r2th An. Rep’t, pl. 24, fig. r29] So large is a quadrate bone in any one of these vultures of ours, that it forms one of the most prominent features upon either the lateral or under view of the cranium. Its “ mastoid process’ is massive and broad, and suggests the idea that it may once have been flat, but subsequently became twisted one third upon itself so as to admit of its condyle articu- lating as it now does in the obliquely placed facet for its reception under the aural arcade. This facet is elongated and narrow. The orbital process of the quadrate is a broad but extremely thin plate of bone, with truncated free end, which is finished off by a little, raised rim. In Catharista the orbital process is very large and of an oblong outline, and here, as in all these vultures, we note at its base, above the condyle of the mandibular end, the subelliptical convex facet for the pterygoid, a special elevated crest being 1 Prof. W. K. Parker has said that “‘In the King vulture (Sarcorhamphus papa) the palate agrees with that of its congener Cathartes; but I find a small mediopalatine, and also much larger and more functional basipterygoids.” This “ mediopalatine * I regard as a rudimentary vomer, and it is found in such other palates as those of the Pici [See Parker. Linn. Soc. Lond. Trans. ser. 2, Zool. 1: 138, pl. 25, fig. 19 mpa]. OSTEOLOGY OF BIRDS 1Oy/ thrown out to support it. In all these birds a marked depression occurs just anterior to this articulation, and immediately above the inner mandibular condyle; it is best seen in the Californian vulture, and is hardly observable in Cathartes a.septentrionalis. The condylar surface on the underside of the quadrate, intended for the lower jaw, is, as usual in so many birds, divided into two irregular, undulating facets, separated by a middepression; the long diameter of the whole being situated transversely. Quite a marked constriction exists between ithe mastoid ard orbital processes and the mandibular end, made apparent by the enlargement of the latter to support the mandibular condyles. The portion bearing the outer condyle is produced outward, forward and upward, as a cylindrical, stout apophysis, having in its extremity the deep, conical pitlet for the reception of the process upon the end of the zygoma. While we are once more within the neighborhood of the orbital cavity, there is yet one point to be noticed in reference to it, and it has to do with that part of the cranium through which the nasal nerves pass. Cathartes a.septentrionalis in its cran- ium offers, a covered, osseous, mesial conduit for its first pair of cranial nerves as they pass from the rhinencephalon to the rhinal chamber. Through the presence of vacuities, in subadult birds, this may be more or less open on its sides in the orbital cavities, but in older individuals, we rarely find more than a pair of small foramina in the lateral walls of this bony passage. By an extension upward of the interorbital septum in Catharista and Gymnogyps the passage is rendered double, so that the nerve of either side has a tube for its own accommodation. Catharista often has the outer walls of this passage quite deficient, while its mesial septum is nearly entire. All Cathartidae have in the back part of the roof of the orbit the usual circular and small foramen for the orbital vein, with a shallow groove leading forward from it. In Neophron it is like it is in the Falconidae, that is, an open channel is provided for the nasal nerves. The pterygoids are horizontally compressed and twisted at their posterior ends in the Carrion crow. They exhibit upon their mesial edges the elongate facets for the pteryapophysial processes of the basisphenoid; these facets are toward the anterior and broader ends of the bones. As we have said, the posterior extremities of the pterygoids are constricted and twisted upon themselves, so as to bring their articular facets to meet those (that were described) for their reception upon the quadrates, while the anterior ends are its) NEW YORK STATE MUSEUM dilated to afford the necessary articular surface for the palatines. These bones do not meet anteriorly in any of the Cathartidae, but form the usual palatopterygoidal articular groove for the rostrum of the sphenoid. From the examination of the skulls of immature specimens of Cathartes:a. septentrionalis, 2 am: meimned: to. 9e- lieve that the orbitosphenoids will be found to exist in the crania of the representatives of this family as separate ossifications. Carrying our investigations forward again, we meet with those interesting ossifications the mavillopalatines, which still remain un- - described for the group now under consideration. In Cathar- tes a. septentrionalis they are almost entirely hidden from our sight upon a basal view of the skull; and it is only their mesial margins that can be observed upon this aspect [see Hayden’s: 12th An, Rept, ypli22) mig. 120)" Upon slaterale viens however, they are plainly visible, and are seen, in each case, to be a subvertical lamina of' bone that reaches from the mesial apex of the triangular and horizontal portion of the ossification, upward and outward to fuse with the correspond- ing nasal and rhinoseptal ossification above. What I have called the horizontal portion, is a thin lamellar piece of bone, growing out from the maxillary toward the middle line to meet the inferoanterior angle of the subvertical plate already described in the last paragraph. This is the arrangement in general in all of the Cathartidae, and can be easily comprehended by a study of any of the numerous vulturine skulls that illustrate this treatise. Huxley placed these Cathartidae among his Desmognathae, and of the desmognathous skull he has said in part that “ The maxillopala- tines are united across the middle line, either directly or by the in- termediation of ossifications in the nasal septum.” [Zool. Soc. Lond. Proc. 1867. p. 435, 436, 460, 463] With these birds this is the case provided we consider the horizontal, internasal ossification of the rhinal chamber, described above, as a portion of the nasal septum; for an examination of the skulls of the young of Cath- artes a.septentrionalis plainly shows, that it is a separate ossification and not developed by the maxillopalatines themselves. My former monograph upon the Osteology of the Cathartidae had in it some additional points upon the skulls of these birds not as yet herein mentioned, and before proceeding to notice the man- dible and other parts, we will allude to them. Among other things, 1 said that the posterior wall of the orbital cavity is quite smooth OSTEOLOGY OF BIRDS 19 and concave from above downwardin Cathartes a.septen- poomaiiscvand Catharista urubu; lessiso in Gypar- chus papa, while in Gymnogyps and the South American con- dor it is nearly flat and slopes away rapidly toward the sphenoidal suture, being marked by several transverse lines or ridges. The “ foramen ovale” is unusually large as a rule in these birds, and is, to be found rather low down in the orbit, almost hidden in the shadow of the great quadrate bone on either side. Posteriorly, the cerebellar prominence is a feature in the crania - of all these American vultures. This is strikingly the case in Gymnogyps, in which species, as among certain others of the Cathartidae, the inferior border of this elevation of the occiput and Fic. 1 Posterior view of the cranium of Gym- nogyps californianus: life size. and mandible removed. Sp, the apsphysial projections, one upon either side of the posteroexternal angles of the basitemporal the superior arc of the foramen magnum are in the same curved line, which line slopes away on either side to terminate in the par- occipitals or lower angles of the raised osseous ridges that bound the ears. This line or ridge forms a striking feature in the rear views of the skulls of the Cathartidae, and is present to a greater or less extent in many of the diurnal and nocturnal birds of prey. The occipital condyle, which has already been alluded to above, is found to be generally larger throughout the vultures than in the Falconidae. We show in our cut of the rear view of the cranium of Gymnogyps [fig. 1], how the region of the occiput is bounded by the superior muscular line, both laterally and above; this line is well marked in all of these vultures. The lines at the sides are 20 NEW YORK STATE MUSEUM quite ridgelike in the Californian condor, parallel and in the vertical plane, while the line forming them above, is a long, shallow arc, with its concavity towards the cerebellar prominence; this is also thescase in .Catharista. aruba sein oC ata ess amie septentrionwalis the side lines are curved outward, while the superior line is broken at its middle point, which point is carried down on the cerebellar prominence for about one third of its dis- tance from above, in the median plane, where the extremities of the broken line join it at a gentle curve on either side. This is nearly the patlern as seen in Gyparchus papa, but in Sarco- rhamphus gryphus we again find it as I described it for the condor of California, only we have in the former a slight in- clination for the point to come down on the prominence. If we remove a section of the vault of the cranium, and this has been: done--here “an the case;08 (Cathar tes ia. *s, eptie mee trionalis and Catharista urn bu, “we nid thamine internal and external. tables are very thin, and that a fair amount of diploic tissue is placed between them, especially toward the occipital region, where, as we approach the locality of the in- ternal ear on either side, it becomes several millimeters thick, the cellular network being more or less coarse in texture. The internal walls of the brain case as thus exposed are smooth, being traversed only here and there by vascular tracts and grooves for the exit of certain nerve branches. The fossae designed for the reception of the different cephalic lobes are moderately well separated, the one that contains the epencephalon being the most distinct, aided as it is by the internal concavity of that external feature of the occiput that we described above as the cerebellar prominence; the usual transverse groovelets do not mark this section here on the internal table. This distinctness is further assisted by thin, horizontal off- shoots from the united bones of the ear cell. The internal auditory foramen is unusually large and predicts a correspondingly good size for this important nervous branch; the same remark applies to the trigeminal and its orifice of exit. Remarkable depth and space is allotted to the fossa for the lodgment of the hypopophysis, the “ sella turcica,’’ as this receptacle is called in anthropotomy, its pos- terior wall being as high as the anterior, and the cavity having a depth of three or four millimeters or more. In our specimen of Catharista urubu, an elliptical perforation exists ini ats hinder wall near the bottom; the carotids seem to invariably pierce its base within, by two openings. Immediately above and anterior to it we find the optic and other nervous foramina. Passing to the OSTEOLOGY OF BIRDS 21 rhinencephalic fossa, we find that this concavity is also spacious, lodging as it does the encephalic lobe that presides over the sense of smell. The orifice of exit for the olfactory nerves is double in Catharista urubu, and some others of the Cathartidae which is ‘an exception to the general rule in Aves. Sir Richard Owen found the same state of affairs in a vulture that he dissected, and he said: In the vulture the olfactory nerve is single on each side, and continued from an olfactory ganglion or ‘ rhinencephalon ’ along the upper part of the interorbital space to be distributed‘ upon - an upper and middle turbinal, the latter being the largest.” [| Anat. Wert. 2123 Along the roof of the cranial cavity, in the median line, the “longitudinal crest” is seen to pass. This may become grooved as it approaches its anterior termination, or for its anterior half, which indeed is the case in the majority of these birds; the groove dilating, and the whole merging into the general surface immediately before arriving at the conical rhinencephalic recess just referred to above. Passing to the hynoid arches of Cathartes a. septen- trionalis, we find that they practically agree with what we find in the South American condor (Sarcorhamphus). As in other vultures the glossohyal remains in cartilage throughout life, and the ceratohyals, as two, slightly curved, elliptical osseous plates im- bedded in it at its base, articulate by the margins of their posterior arcs with the facets on the anterior aspect of the first basibranchial ; they are also tangent to each other at their middle points in the median line. The first basibranchial is included in the great fleshy base of the tongue in these birds, and is characterized by an osseous keel along its nether aspect, while it is somewhat expanded laterally. The second basibranchial is a slender spine, coossified with the first and tipped off with cartilage behind. The thyrohyals and the ele- ments that compose them are simple, being subcylindrical, some- what curved rods of bone, the posterior pieces being finished off with cartilage. I have not especially examined the intrinsic ossifications of the ears in our vultures, and the only example of the sclerotal plates that I have is a set from the eyes of a specimen of Cathartes a. septentrionalis. In this vulture they number 15 in each eye, are very broad, overlapping each other by about one fifth of their extent; their corneal margins are turned outward, while their sclerotal ones are reflected in the opposite direction. I have but little doubt that when opportunity for examination offers, this 22 NEW YORK STATE MUSEUM . description will apply very closely for ithese platelets among others of the Cathartidae. In contradistinction to the Falconidae and the Old World vul- tures, the members of this family are armed with much more power- ful mandibles, the increased strength lying principally in the greater depth of their rami and consequent breadth of the symphysis, as well as the ponderous articular extremities, that these jaws possess. The vacuity, forming such a characteristic feature on the sides of the mandible in so many of the class, is here rarely or never present. In Gymnogyps its location is merely indicated by a shallow slit, that does not penetrate to the bone below, though in Gyparchus papa it does for a limited distance along the base of a similar slit, but in our specimen of Sarcorhamphus gryphus every trace of the locality of the foramen has been obliterated; again in Cathartes and Catharista narrow and faint groovelets are the sole indicators of its position, or the margins of the. elements that originally bounded it. Deep pits are found in the centers of the upper surfaces of the articular ends; these are bounded externally by narrow, longitudinal facets, as do the inturned conical processes support more irregular ones. In the Californian condor there is a predisposition to develop from these articular ends quadrate apophyses behind, but this does not seem to be so much the case in the others. The under surface of either articular end is divided into two by a longitudinal ridge, continuous with the lower ramal border; of these two surfaces, the lesser and outer faces outward and downward, while the inner and larger downward and toward the median plane. Almost an unbroken smoothness characterizes the internal and external surfaces of the sides of the jaw; this is extended to the entire dentary region beyond. Even the ramal borders bounding these surfaces above and below are evenly rounded off, there being scarcely any evidences of the coronoidal projections to interrupt this general smoothness; it is only in the superior one, for its anterior third on either side, and as it sweeps around the curve of the symphysis, that it becomes sharp, to correspond with the tomial edges of the mandible above. The depth of the symphysis in Gymnogyps is about 2 centi- meters, and the deepest part of the jaw, the ramus just beyond the articular ends, is 1% centimeters; forC athartes a.septea-— trionalis and Catharista urwbw the ‘measurements are equal. The curve that is continuous with the lower ramal borders, OSTEOLOGY OF BIRDS 23 limiting the symphysis posteriorly, is parabolic in outline. View- ing the mandible: in the Cathartidae from a lateral aspect, when it has been articulated with the cranium, we observe that it is bent downward from a point a little posterior to the dis- tal end of the maxillary, from which point it is obliged to accom- modate itself with the superior mandible. A row of foramina is always present just within the sharp edge of the superior border beyond, and still within these a few others are scattered about; one or two isolated, though parial, nutrient and vascular foramina are found at corresponding points, along the sides of the mandibles of all these vultures. Vertebral column. Being large boned birds generally, we find that in the Cathartidae this feature is extended to the segments of their spinal columns. The vertebrae are large, and all their various processes well marked and strong. In the cervical region or division of the column we find the verte- bral canals as usual, passing from vertebra to vertebra, along on either side; in each segment the tube remains throughout more or less subcircular, and is closed in the ordinary manner by the para- pophyses and pleurapophyses of each vertebra. The protection afforded the vessels is markedly complete, for it is only in the atlas and axis that we discover slight deficiencies in the lateral walls. ‘The neural canal as it passes through the vertebrae of the upper half of the neck is nearly cylindrical, but as we approach the middle of the neck it gradually becomes compressed from side to side, and assumes the vertical ellipse, to become circular again before arriving at the dorsal region. In the atlas the facet for the condyle of the occiput is semilunar in outline, and the neurapophyses are broad above, but as usual exhibits no sign of a neural spine. Below we commonly find a well marked hypapophysis, though this feature is absent in Catharista urubu ; laterally we have the un- closed vertebral canal of this bone, the processes receding from each other as sharp spiculae. These points are still nearer together in the axis, and in this segment we find a thick, quadrate, neural spine occupying the center of the arch above. Below, the hypapophysis is carinalike in character, traversing in the median line the entire cen- trum of this bone. The odontoid process is an insignificant tip, being quite broad from side to side, while the postzygapophyses are tuberous lateral projections, with the facets on their under aspects in the horizontal plane, looking directly downward, with the anapo- 24 . NEW YORK STATE MUSEUM physial projections above, elevated into prominent though blunt — tuberosities. ; The facet for the third vertebra is convex from side to side, and looks almost directly upward, it facing slightly backward; the similar surface for the atlas, anteriorly, being much more extensive, - twice as broad, continuous with the articular surface beneath the odontoid process, is directed forward. Solidity and great breadth marks the third cervical vertebra; in it bony laminae connect, on either side, the pre- and postzygapophyses, an elliptical foramen be- ing found in the surface near each lateral margin. There is a con- spicuous neural spine with thickened crest, while below we have a quadrate hypapophysis. The vertebral canal is completely closed in, and paridl parapophysial processes begin to make their appearance, being directed backward; in all ‘of the vultures these spinelike appendages are long and styliform in mid neck, to become broad and tuberous as we proceed dorsalward. Facets upon the pre- and postzygapophyses of this vertebra are elliptical in outline and comparatively large; the former are directed upward and a little forward, the latter almost directly downward. The anterior facet of the centrum, below and immediately outside the neural canal, partakes of its usual ornithic characters; it is very narrow from above downward and decidedly concave from side to side. In this vertebra, the last remnants of the carotid canal are present-n all of the Cathartidae; it is formed in its usual man- ner as we pass down the serial segments. InSarcorhamphus gryphus its first appearance is made in the 11th cervical, but in the roth in Gyparchus papa, as is also the case in Carthartes:a.iseptientrd ona las and Caraga: More or less complete interzygapophysial bars are found joining the process laterally in the fourth vertebra. The hypapophysis of this segment is reduced to a low ridge beneath, while superiorly the neural spine still projects from the lamina, mesiad, as a vertical peg- like process. ‘The articular facets are about as we found them in the preceding vertebra. As a rule, the hypapophysial process throughout the cervical series, after passing it when it is double for the carotid-arteries, is found better marked on the next two or three ultimate vertebrae. Those cervical vertebrae that possess free ribs rarely show a dis- tinct hypapophysis, but in them the centrum beneath is broad and oblong in figure with a faint ridge mesiad at the usual site. OSTEOLOGY OF BIRDS 25 Another suppression takes place on the part of the neural spine among the vertebrae found in mid neck; it is but feebly developed in the fifth segment, still more so in the sixth, and is nearly lost in the few following vertebrae as we proceed down the neck. It soon reappears -again, however, as a broad, knotlike apophysis, to become compressed from side to side, quadrate, and finally like the anterior dorsals. In the Cathartidae we find upon either side a transverse process jutting out from the wall of the vertebral canal, laterally and at the anterior part of the vertebra; this character is best marked as we approach the dorsal region, and we find that upon those cervical vertebrae with the frée ribs it is quite broad and exhibits a metapo- physial ridge. Upper cervical vertebrae show long postzygapophysial processes, and throughout the series the arms bearing these articular facets are shortened or lengthened in such a manner as to preserve the decided sigmoidal curve so characteristic of the vulturine neck. As we arrive at the middle of the cervical chain of segments, we notice that the anterior articular facets are barely concave, face directly inward, and so each other, occupying a position, on either side, on the bony ridge that spans the vertebral canal above. Epipleural appendages are never found upon the free ribs of the cervical vertebrae in any of the American vultures, and this seems to obtain pretty genefally among the Falconidae, though these ribs become more and more like the true dorsal ones as we proceed in their direction. TABLE FOR THE COMPARISON OF THE VERTEBRAE —— SS —— Es Number te Coccygeal, vee pa of | Number Cervi- exclusive |free pleura-| of pairs SPECIES cals Dorsals | Sacral of the pophyses | of sacral pygostyle | or cervical ribs ribs Gymnogyps californianus...| ...... | ....-. Teg hal ake ec ite creeks [Pikes cucu suevacen Iieretcueus oycus Sarcorhamphus gryphus... 17 3 13 6 2 3 Gyparchus papa........... 17 3 13 6 2 3 Carthartes a. septentrionalis 15 4 13 5 2 2 Catharisha, urubte 70... 2). 15 4 : 14 5 3 3 Neophron percnopterus.... 15 4 15 6 2 | 2 Micrastur brachypterus.... 14 5 13 7 3 I eee — Lateral wings are seen to project horizontally from the centrum of the ultimate cervical beneath, and as we pass to the first dorsal, in the majority of the Cathartidae, these wings still persist, but 26 NEW YORK STATE MUSEUM are not so far-spreading, and are, as it were, drawn downward at the expense of the centra, the latter becoming more compressed, the former, now attached by a quadrate pedicle, are true hypapo- physes with flattened and expanded extremities, which latter con- tract, and the pedicle becomes longer as we approach the sacrum. These are very prettily shown in Sarcorhamphus gry- phus, and in all of our vultures are a striking characteristic of the dorsal series. Rimlike projections are observed to bound the facets of articu- lation among the centra in the dorsal division of the spine; and these centra are laterally subcompressed at their middles and rather deep in the vertical direction. This does not, however, influence the cylindrical form of the neural canal, which retains that shape throughout, especially miC athartes as Sep temirionmalens: Dorsal nerves from the spinal cord issue from between the verte- brae, which latter are indented both anteriorly and posteriorly to admit of it. At the base of the transverse processes of these dorsal vertebrae, and again at their extremities, semicircular facets exist for the capitula and tubercula of the dorsal ribs. Those at the bases are upon slightly raised elevations and look almost directly outward, those at the extremities look downward and outward. This is the case in Carthartes a) septemtr ona lis sandy ieee arista urubu, but in the condor and in Gymnogyps they face almost directly outward, especially in the last dorsal. The diapophyses become progressively longer as we near the sacrum at the same time more inclined upward; they are com- pressed from above downward, being dilated at their outward ex- tremities, where they bear distinct and styliform connecting meta- pophyses, the last pair being extended to the pelvis in Cathartes. Close and mutual locking is accomplished in this region, principally by a shortening of the pre- and postzygapophyses, the facets upon the former facing upward and slightly inward, upon the latter down- ward and slightly outward, so as to be nicely approximated in the articulated skeleton. With the exception of the vertebrae that are grasped by the pelvic bones, these segments in all of the Cathartidae are freely articulated with each other. This is likewise the case with Gypogeranus and Neophron percnopterus, and obtains also with our Circus hudsonius, in which species five vertebrae are allotted to the dorsal division of the column. Again, we find itin Accipiter cCooperi a witlesm iim. OSTEOLOGY OF BIRDS 27 (imowians. Sparverius and Polyborus tharus at least four of these vertebrae form one solid bone in the adult specimen; in Micrastur brachypterus there are again five dorsals, and all independent segments. Sharpened ridges beneath the transverse processes connect the facets for the capitula and tubercula of the ribs; this feature is best matked intCarthartes a. Sseptentrieona li’s and next in Gyparchus papa, less so in the others. Vertically elongated but shallow depressions occur above the cen- tra on the anterior and posterior margins of the neural spines, for the insertion of the broad connecting ligaments; the spines them- selves spring almost abruptly from the neurapophysial arch, are uni- formly quadrate plates of an equal hight, with thickened crests above, that become united at their anterior and posterior ends by a modified arrowhead joint, such as we see in the owl Speotyto, where the points are more acute.! 1 Before closing what we have to say about the spinal column, I wish to footnote here my views of many years ago upon the question as to where the division should be made in the cervicodorsal region of the spinal column. It is from my Osteology of the Cathartidae and I said: ‘‘ The manner in which the vertebral column of birds should be divided has been differently viewed by ornithotomists. The two principal reasons for this difference of opinion, no doubt, has arisen from the various arrange- ments assumed by the free ribs at the anterior part of the column, and the equally diverse manners in which the innominate bones of the pelvis attach themselves to the column. Without entering very extensively into the literature of the subject, let us first examine into the question as to where the line shall be drawn between the cervical and dorsal vertebrae. We seem to have presented us here two very uncer- tain guides; the first being whether the first free ribs are connected with the sternum by sternal ribs or haemapophyses, and the second upon the character of the vertebrae — that is, whether they have the appearance of dorsals, as we commonly find them, or cervicals as we usually recognize them.’’ Professor Huxley sharply defines the line when he says: ‘“ The first dorsal vertebra is defined as such by the union of its ribs with the sternum by means of a sternal rib; which not only, as in the Crocodilia, becomes articulated with the vertebral rib, but is converted into complete bone, and is connected by a true articulation with the margin of the sternum.” [Anat. Vert. Animals, p. 237] Professor Owen takes a different view of the subject, when he states that ‘“‘In the first and second dorsals the pleurapophysis (1 and 2) terminate in a free pointed end, like the ‘ false floating ribs’ of Anthropotomy; in the third the pleurapophysis, plate 3, articulates with the haemapophysis fi; which, in connection with its homotypes, constitutes the bone called ‘sternum,’ f.’”’ The letters given refer to a cut showing the first three dorsal vertebrae and scapular arch of a bird, in diagrammatic side view [Anat. Vert. 2:15]. I have found in Otocoris the second pair of ribs free, they being connected with the sternum by haemapophyses in another specimen of the same species, so that in this case some would claim them as true dorsals, or as dorsals any way (Owen); while others could but say that the number of pairs of dorsal ribs varied. This state of affairs in Otocoris is no more an unusual occurrence than the occasional presence of cervical ribs in man [Owen, Anat. Vert. 2: 298]. Now, among the Tetraonidae we found another condition that proved equally interesting; with them there are, in the backbone in the dorsal region, four vertebrae that in the adult completely fused together, and the pairs of ribs that articulate with the anterior vertebra of this compound bone do not connect with the sternum by haemapophyses. Here we must, if we consider the floating ribs in this region as cervical ribs, considér that a cervical vertebra has become anchylosed with 28 NEW YORK STATE MUSEUM Unfortunately, all that remains of our specimens of Gymnogyps so far as the vertebral column is concerned, are a few of the free ribs and several scattered vertebrae; two of these are the third and fourth cervical, another one from the middle of the neck; one of the last cervicals and lastly the ultimate dorsal — this latter we have devoted a figure to, representing as it does no doubt the largest _ avian vertebrae of any living form to the northward of the range of the South American condor — nevertheless, we think we may predict, almost with certainty, that even from these two fragmentary pieces it will be found to be the case, that when the opportunity offers for an examination of ia perfect skeleton of this bird, that the number of segments in the spinal column will be the same as in Sarcorhamphus ; we have been assisted in arriving at this conclusion by a critical examination of the ribs we have, as well as the sternum and sacrum, that come very near to Sarcorhamphus gry- plus . The caudal vertebrae are very much, modified, as they are, as a rule, throughout the class; the number possessed by each species of the Cathartidae has already been given in the table above. In the South American condor a complete arcade is formed by the neurapophyses of the coccygeal vertebrae, oyer the ultimate divi- sion of the myelon,. and even the pygostyle is pierced for a short distance to allow the entrance of the nervous cord. These bony arches are surmounted by knoblike tubercles throughout the series, that show a very feeble disposition*to become bifurcated at their summits. Many of the lateral elements of the vertebrae are com- bined to form diapophysial processes, which in this bird, are heavy and broad projections jutting from the centra on either side, bent | downward, becoming wider and wider as we near the coccyx, to be suddenly suppressed in the ultimate segment. Very faint indi- cations of a hypapophysis occur in any of the first three caudals; in the fourth a cleft but sessile tubercle is seen, that leans forward to rest upon the under surface of the centrum of the vertebrae be- three dorsals, together forming a bone that we believe every one would, as the writer then did, say was composed of dorsal vertebrae alone, in spite of the anterior ribs not joining the sternum by sternal ribs. One other case, and let us take a specimen of Asio. wilsonianus to illustrate it [see Am. Phil. Soc. Proc. 1900, v. 39, no. 164, p. 682, fig. 6]. In this bird we discover, passing from before backward, that the first pair of free ribs hang from beneath the transverse processes of the vertebra as diminutive bonelets, as we found them in Speotyto. Now, the next vertebra behind this one has all the appearances of a true dorsal vertebra (possessing the lofty neural spine, etc.); but the ribs still fail to connect with the sternum by sternal ribs. These three varieties may be again divided when we come to consider the appearance or nonappearance of uncinate processes upon three ribs, a condition which likewise varies. Fic. Fic. Fic. Fic Fic Fic. Fic. OSTEOLOGY OF BIRDS 29 Pygostyles of various Old and New World vultures and Hawks (a.a’)Sarcorhamphus gryphus (b. b’) Gyparchus papa (c.c’)Cathartesa.septentrionalis .5 (d. d’) Catharista urubu :6 (e, e’) Neophron percnopterus 7 f.f’) Gypogeranus serpentarius 8 (g) Otogyps calvus (after Lucas) wb Fic ae Fic. Fic. Fic. Byres . 9 (g’) Vultur cinerea (after Lucas) to (h. h’) Falco sparverius Ir @. 2’) Accipiter cooperi t2 (7. 7’) Micrastur brachypterus 13 (k. k’) Circus hudsonius rae eeolyborws t harass 30 NEW YORK STATE MUSEUM yond; in the last two this process becomes much larger, and is evi- dently made up of the haemapophyses of the vertebrae, for in each case it is pierced by a delicate haemal canal, while the true hypa- pophysis is still below and still exhibits the disposition to overlap the vertebrae beyond. The centra of the coccygeal segments of the spinal column in the Cathartidae, as among the class generally, are procoelian. In the coccygeal vertebrae of Gyparchus papa we find the same general characters present that we have just attri- buted to Sarcorhamphus gryphus; the principal differ- ences are that the neural spines are more lofty and only the ultimate hypapophyses form a perfect haemal canal, the anterior ones being only grooved. Among the vultures the first caudal vertebra, free in some specimens, anchyloses with the sacrum in others. In ~G@a ths rtiessica.. septentrio nalis the neural canal is complete throughout the chain and enters the pygostyle for some little distance; the haemal canal does this also below, but this latter only passes through two of the hypapophyses of the last two caudals, these processes being but feebly developed in the others. The diapophyses in this vulture become gradually broader and shorter as we leave the sacrum. Catharista exhibits about the same peculiarities with regard to its caudal vertebrae as we see in Cathiartes a. ise p' ten t'r-1omiadhis (plea snowzel|e Mr Lucas tells me that he counts seven caudal vertebrae both in Otogyps calyvus andi WV wlttr ic inte re ae neraam kindly furnishes me with outline sketches of the pygostyles of these two vultures, which we give below as we compare them with others [ig. 8 (g), 9 (g") | It will be observed, from the figures presented in the accompany- ing cuts, that as a rule the coccyx among the Cathartidae is more or less parallelogramic in outline, with well defined angles; on the other hand, among the Falconidae and their allies, this bony plate is drawn upward and backward into a rounded point. Neophron has a strong tendency falconward in this respect, less marked in Gypogeranus. : The number of the dorsovertebral ribs in any of the Cathartidae can easily be ascertained by consulting the table I have given above, as, of course, every dorsal vertebra has its pair of free dorsal ribs, these being articulated in the usual manner with the sternum, by the intervention of the sternal ribs. The ribs as found among our American vultures are very robust and strong bones, which is quite. in keeping with the general massiveness of the skeleton of this family. As is most usual in the class Aves, the neck bearing the capitulum OSTEOLOGY OF BIRDS ar . > of the rib at its extremity lengthens as we pass backward toward the pelvic end of the body, in due proportion does the one bearing the tuberculum shorten, until in the latter we have the transverse process of the vertebra, in the last dorsal, resting for the outer third of its length against the true neck of the rib opposed to it, and the tubercular pedicle has become sessile with the body of the rib. The ribs of the Cathartidae, or such of them as are found in the dorsal division of the spine, are very broad throughout their entire lengths, the broadest part being found at their superior thirds; this transverse compression gives rise to sharp anterior and posterior borders, and long elliptical facets, placed longitudinally. below for the sternal ribs. All of the dorsal ribs support epipleural appendages in the Ca- thartidae, and they are anchylosed to the posterior margins of these bones, below the middle of their shafts. We believe that this is the case in the vast majority of the Falconidae, including the Old World vultures. These unciform offshoots of the ribs are very widespreading and prominent, more so among the American vul- tures than in any of the hawks or eagles, and as a rule overlap the rib immediately behind them, but never two consecutive ones, as in some birds. : There are some véry interesting and distinctive differences be- tween the ribs of the Cathartidae and those bones as they occur among the Falconidae and the vulturine Raptores of the continent; these differences are principally due to the various patterns as- sumed by the epipleural appendages now under consideration, as well as changes in form of the bodies of the ribs themselves. Our figures, herewith presented, exhibit these differences so well, that it seems to render any special description unnecessary. Especial attention, however, is invited to the form assumed by the epipleural process, and the relative width of the body of the rib. They attest, even in this minor character, to the affinities of the various forms compared. Neophron practically agrees with the Falconidae, and the Cathartidae exhibit a family character peculiar to themselves. Attention is particularly invited to the descending part of the epi- pleural appendage in our vultures, and this is most strongly marked in the ribs from the middle of the dorsal series; it being entirely absent in the Falconidae and their allies. | The first dorsal rib in Gypogeranus serpentarius bears no epipleural appendage; in the second it is broad and short, with a minute descending process below, very close to the margin of the rib; in the third this unciform appendage is long and narrow, 32 NEW YORK STATE MUSEUM and is in contact with the rib for its entire length, sloping away below; in the last dorsal it appears only as an increased widening of the rib for a certain distance along the usual site of its occupancy. Sternal ribs agree with the dorsal ribs in being strong and robust; they possess quite extensive quadrate facets for sternal articulation at their lower ends, and these bones when articulated im situ are so placed that their anterior faces are visible from a direct lateral view. Fre. 15 Ribs of Cathartidae and Falconidae; m, rib from anterior dorsal vertebra, left side, Gymnogyps; ”, the same from the second dorsal vertebra of Catharista urubu; o, the same from Neophron percnopterus; p, the same trom Circus hudsonius. All natural size. Their posterior ends are progressively, from before, backward, curved in such a manner as to preserve the oval form of the chest walls, and are very much dilated as we proceed in that direction; at their distal extremities they support the usual facets for the verte- bral ribs. In the Secretary vulture they become very much com- pressed from side to side as we examine them successively in the order referred to, and in this course, too, in some of the Falconidae, they become curved in an anteroposterior direction, the concave margin being in front. In these birds, and in Neophron, the sternal ribs are seen to be much slenderer than corresponding bones in the Cathartidae [see fig. 15]. OSTEOLOGY OF BIRDS 33 Sarcorhamphus gryphus _ has three sacral ribs upon either side; the first two pair support epipleural appendages and articulate with the sternum through the agency of well developed sternal ribs. The last pair are devoid of unciform projections, and their sternal ribs in turn articulate by their distal extremities and a small portion of their distal and anterior margins along the posterior borders of the sternal ribs in front of them, their points coming within about a centimeter of the costal border of the sternal body on either side: Gymnogyps will probably be found to possess the same arrangement of its sacral ribs as has just been described here as obtaining in the Condor. Gyparchus possesses two pairs of these ribs, both articulating with the sternum by sternal ribs that are the largest and longest of the series. The first pair have unciform pro- cesses. Sometimes in this species. an additional rudimentary pair are found to exist, and belong to the next vertebra beyond, but all the distinctive characters of the upper part of a rib have been ab- sorbed by the under surface of the ilium, so that this pair almost has the appearance of being offshoots from the ossa tnnominata. In Cathartes a.septentrionalis we discover two pairs the first connecting with perfect sternal ribs coming from the ster- num below, and support epipleural appendages; the last are without them, and otherwise behave as we described the ultimate pair in Sarcorhamphus. Passing to Catharista, we find the same arrange- mci oreseh: isin Cathartes a. séptentrionalis ;-but in addition a pair of rather long styliform, rudimentary ones are found, with their capitula, tubercula, and their necks aborted as in Gyparchus, though evidently belonging originally to the next verte- brain order. So then, among the Cathartidae the variations observ- able among the plans for the sacral ribs resolve themselves into the following four classes: as to the number of pairs; as to the presence or absence of rudimentary ribs; as to the method of articulation of the last pair of sternal ribs, i. e. whether these descend to the ster- num or not; and finally, as to the arrangement of the unciform ap- pendages. Turning to the vultures of the Old World, we find that Neo- phron percnopterus has a free pair of sternal ribs that articulate with the sternum, but no sacral ribs that join them from above. Similar ribs are found in Vultur cinerea and Gyps bengalensis, “but they do not even reach the sternum” [Lucas]. The authority just quoted further states that in Oto- gyps calvus “a very small floating rib is attached throughout 34. NEW YORK STATE MUSEUM its entire length to the last articulated sternal rib.” This no doubt occurs upon both sides and corresponds to what we found in. Gypogeranus, only the rib is longer in this latter vulturine falcon. Cases of asymmetry no doubt occur among many or all of these various arrangements, as, for example, in the skeleton of Micras- tur brachypterus at hand, we find six sternal ribs on the® left side all meeting the sternum, and but five upon the right, the — sixth one articulating with the posterior border of the sternal rib in front of it. Scapular arch, sternum and pectoral limb. All the bones of the shoulder girdle are well developed in the family of birds now under consideration, and none of them are fused one with the other, or with the sternum. There is a very great similarity, both in outline and general appearance of this arch as it exists in the Cathartidae, and to this we may add that when the bones forming it are in situ in the articulated skeleton they present a pattern that not only pos- sesses a common resemblance, but is peculiar to the family, and dif- fers very decidedly from the vultures of the Old World and from -the Falconidae. We find in our present subjects that the sternal extremities of the coracoids are very much expanded in a transverse direction, that they touch each other, mesiad, when articulated in the sternal grooves or beds designed for them. These dilated ends are scooped out on their posterior aspects where the pneumatic foramina occur, and roughened, while in front the surface is smooth, convex from side to side, and continuous with the general surface of the shaft. The inferior side is occupied for more than its inner half by the facet for articulation with the sternum; this is broadest mesiad, narrowing in each bone as we proceed outward. The outer angle is truncate and presents an upturned tip of bone, and a face that is directed outward. Very little shaft can be boasted of. by these bones, for no sooner do the fanlike lower ends commence to merge into a shaft, than dilatation immediately sets in again to form the great tuberous heads that constitute the opposite and superior ex- tremities. More of a true shaft exists in Catharista than in any other of these vultures, for the coracoids are proportionately longer in this species; in all it is more or less compressed from before, backward, rounded externally, sharper within, where in each bone it is pierced midway by an elliptical foramen, such as is found in the owls and other birds. This last feature is scarcely perceptible in the Carrion crow. In each the facet for the scapula is behind and rather toward the median plane; it is placed transversely upon the OSTEOLOGY OF BIRDS 35 bone, occupying the upper surface of the scapular process, and is continuous with the shallow glenoidal facet that is seen on the outer aspect. The coracoids terminate superiorly in rounded heads that are flattened from side to side, and present upon their mesial aspects smooth surfaces for the broad clavicular limbs. The blades of the Fic. 16° Right'coracoid of Gymnogyp viewed from in front. Life size scapulae are short and broad, being curved outward, with rounded points ; they never reach back nearly so far as the pelvis, but gen- erally overlap the last pair of dorsal ribs. The heads of these bones are flattened from above downward, curled up on their inner aspects, so as to afford surface to articulate with the points of the clavicular ends, while externally they present raised elliptical facets 36 NEW YORK STATE MUSEUM that go to complete the glenoid cavities of each shoulder joint. The entire anterior margin of a scapula is devoted to the articular facet for the coracoid. The glenoid cavity formed by the approximation of these two bones is quite deep and extensive, and I find no os humero scapulare present. Os furcula is of the broad U-shaped pattern. Superiorly this bone presents for examination the great flattened ends that articulate with the coracoids and scapulae on either side; these are drawn out into rounded points behind to reach the latter, while a limited smooth surface on the outer aspect of either limb comes in. contact with a similar surface on each of the former. All the mesial surface of the os furcula is smooth and devoid of any points of particular interest [pl. 13, fig. 28]. Externally and above, we find the entrances to the great air passages, for they are more than foramina, that lead into the bone. No hypocleidium projects from the thoroughly united clavicles of these birds below, but a little ridge occupies the usual site beneath and a characteristic tip projects from in front in all of them. Behind, the borders are rounded; in front, they are sharpened and produced out to the point of the aforesaid tip or anterior projection. With the scapular apparatus in position, we find that the axis of the shafts of the coracoids is in line with the long axis of the sternal body; that these bones diverge from each other at an angle that is equal to the angle of the clavicular fourchette. From behind their heads the articulated scapulae spring out at nearly right angles, and pass backward parallel with each other, to be deflected outward only as we near their posterior points or extremities. After closing in the large “ tendinal fora- mina” by its broad superior dilatations, the furcula dips directly ‘backward to bring its lower arch into the recess of the anterior concavity of the carina of the sternum, but it never touches this bone at that point, and its near approach seems to vary for the same species; it is quite distant in a skeleton of the King vulture at hand; while in another it comes much nearer. In the vast majority of the diurnal Falconidae of this country, and, no doubt, in those of the Old World too, the clavicular heads present a much more intimate articulation with the superior ends of the coracoids than we have just ascribed to the Cathartidae. _ This arrangement is closely followed by Neophron, and, in short, the entire scapular apparatus of this bird is indubitably stamped with the well known characteristics that mark this arch among the hawks and eagles. , OSTEOLOGY OF BIRDS By Figures 17 and 18 exhibiting the method of articulation of the bones of the shoulder girdle, holds good for all members of the Cathartidae, and in them the clavicular head simply rests against the inner side of the coracoidal capitulum, while on the other hand in Neophron and in many of the Falconidae, 1f not in all of them, the coracoid is actually molded upon the clavicular head, or perhaps it had better be said, that the latter is accurately impressed by the head of the coracoid with which it articulates, the articulation being very close and intimate. As it is, it stands as another good character pointing to the affinities of the Old World vultures and Falconidae, as separated from the family now under consideration. Fig. 17 Fig. 18 Articulations of the bones of the shoulder girdle. (Outer aspect. Natural size) Fig. 17 Catharista urubu. Natural size Fic. 18 Neophron percnopterus; natural size. Left lateral view in each case; 7, os furcula; O, scapula; @, coracoid pie ah ai ase Among the Cathartidae we find the sternum to be a bone that varies somewhat in its form for the several genera of the family. In the first place, it presents no distinct manubrium as it does in Neophron and in the Falconidae, this feature being supplanted by a massive and tuberous promontory in the median line, over which the broad concave corocoidal grooves meet at the middle point above. From thence these grooves are produced shallower, nar- rower, and less distinct to the deep pneumatic fossae that are found upon either side, and which are situated just below the facet for the first sternal rib on the costal border in all Cathartidae. The body of the sternum is oblong and deeply concave, being wider behind than it is anteriorly, and longer for its width in Catharista than it 38 NEW YORK STATE MUSEUM is in any other representative of the family. The general internal surface is very smooth and rounded, there being not even any median indication of the position of the keel. All of the borders of the sternum are sharp and thin, except the anterior moieties of the lateral ones, and these are more (Gym- nogyps) or less (Cathartes) occupied by the facets for the sternal ribs. These latter are small parallelograms, varying in size accord- ing to the rib they support, being placed transversely and tipped slightly outward, and separated from each other by subelliptical depressions that show the pneumatic openings at their bases. Upon its pectoral aspect the body of the sternum is likewise smooth, and presents for examination the prominent pectoral ridges, on either s:de, which originate in eminences in the middle of the costal borders to be produced backward and terminate just anterior to the midxiphoidal prolongation at the base of the keel. This latter is very deep and strong in all of the Cathartidae; commencing, as it does, below and within the manubrial prominence, it extends to the extremity of the sternal body behind. Its anterior margin is always thickened, as is its inferior border in Gyparchus and the con- dors. A well marked muscular line is found on either side of the keel, a few millimeters within its inferior boundary, extending from the carinal angle to be gradually lost before arriving at the posterior termination of this part of the sternum. It is less distinct in Gyparchus and the condors. There is no exception among the Cathartidae to the fact that the xiphoidal end of the sternum exhibits a number of patterns for the same species; a circumstance that may be due to slight differ- ences in age, but which, nevertheless, detracts from the reliability of this bone as a structure upon which to base classificatory indi- cations. When we come to examine a sufficiently large series of sterna from any species of the Cathartidae, it will not appear strange to us that the figures of this bone, as presented to us by different workers, never appear to agree in outline, any more than do their written descriptions of the sterna of these vultures. This is due, as we have just remarked, to the variations to be seen in the notches and foramina of the hinder portion of the body of the bone; but more especially the foramina, and the notching 1s pretty constant for any particular species. This variation is ex- tended to the Old World vultures, as well as to many of the true Falconidae. OSTEOLOGY OF BIRDS 39 As a good instance of it we may select as illustration various sterna and descriptions of sterna of Cathartes a. septen- ten eon a TiS: In the xiphoidal extremity of the sternum of this vulture, there is an inner notch and an outer foramen upon the left side, and two notches upon the right, the outer one of which is almost a foramen. Now, in a specimen in the United States Army Medical Museum, the sternum is singly notched upon either side, and no foramina at all. Specimen no. 6897 of the Smithsonian Collections is similarly notched, but has an outer foramen on the left side and two of them on the right. No. 692 of the same collection is also similarly notched and has in addition a foramen only on the right side external to the notch.! Mr T. C. Eyton, in his Osteologia Avium [London, 1867], in a ale yviews-on (the, sternum vot -Cathartes*-a. septen- trionalis, found it as in specimen 692 just referred to above, only the foramen was somewhat larger [pl. 1, fig. 2]. We, how- ever, read in the text of his work [p. 19, 20] “ Sternum in general shape similar to Sarcorhamphus, but with two large fissures on the posterior margin next the keel, and two fissures exterior to them; the remaining portions of the skeleton are very similar except in measurement.” Now here is a writer who actually contradicts his own drawings by the statement he makes in the text, and we can only believe, that Mr Eyton could have been led into such an apparent error by having several specimens of the sternum of this bird at his disposal, availing himself of one for his drawing and of another for his description, perhaps at a later date. Now all the sterna I have examined of Catharista urubu have two notches upon either side of the carina, yet Eyton figures the sternum of this vulture with a large,. elliptical foramen upon Cathiattes ce either side in lieu of a pair of the notches [cf. Aiwer” |. The various forms taken on by the sternum of Cathartes a. septentrionalis, and what I have said about them, applies likewise to the sternum of Gyparchus papa, and I have examined a number of specimens and read Eyton’s remarks in the case, too, both of which go to prove it. And, in short, it will prob- 1In my Osteology of the Cathartidae I present figures of these various sterna of Cathartesa.septentrionalis, but those figures are not repzoduced in the present connection. 40 NEW YORK STATE MUSEUM ably apply in general to all of the Cathartidae, it having been noticed by a number of anatomical writers of authority, Owen among others, who speaks of it in his Anatomy of Vertebrates. Undoubt- edly age has much to do with the condition, and I am quite sure it has among the Falconidae where the same condition exists. Mr FF. A. Lucas, who kindly examined the specimens of the Old World vultures in the Natural Science Establishment at Rochester for me, writes, “You will notice that the right sternal foramen of Neophron is closed (referring to a specimen sent to the Army Medi- cal Museum) ; this was also the case with a second specimen, while a third, somewhat younger, had the foramen open, but much smaller than the left. A specimen of Neophron from North India has both foramina open, and there are a few trifling differences between its skull and that of the Abyssinian specimens.” The keel of the sternum in Gyparchus has the anteroposterior curve along its lower margin, as we find it in Gymnogyps and Sarcorhamphus (S. gryphus, G. californianwus) ; this outline is faintly imitated by Catharista, but in this bird the border is not nearly so thick in proportion. Cathartes has a convexity peculiarly its own, as distinguishing it from others of the family. The sternum is eminently falconine among the Old World vultures in its general form and outline. Professor Owen, contrasting the relative lengths of the segments of the pectoral limb as observed in the class, refers to it as found in the “ powerful raptorial flyers,” as showing an intermediate and more harmoniously balanced proportion of the several segments. This is the case, in a marked degree, with our American vultures, for here we find almost perfect examples of relative proportionment among arm, forearm, and pinion, not only as regards lengths, but the calibers of these long bones. We present a table of the lengths of segments of the pectoral limb, given in centimeters and fractions of the same, for the members of the family under consideration, and add also measurements taken from Gypogeranus and N eo- phron percnopterus for the sake of comparison, “In all of the long bones the straight line joining the points farthest apart in distal and proximal extremities was taken as the line to measure upon; in the pinion, it was the straight line let fall from the highest point in the metacarpus to the extreme tip of the distal phalanx, the limb being closed. OSTEOLOGY OF BIRDS 4! TABLE SHOWING THE LENGTHS OF THE BONES OF THE PECTORAL LIMB IN THE CATHARTIDAE, GIVEN IN CENTIMETERS; ALSO OF NEO- PHRON PERCNOPTERUS AND GYPOGERANUS SSS Ee | SPECIES HUMERUS | RADIUS | ULNA | PINION Gymnogyps californianus........... 27.8 Zia! 2208 24.5 Sarcorhamphus gryphus........... 27 Boece || ese) 2305 Gypacehus: “papa. cic f.25 soa ce vesy0 17 20.4 | 21.6 ig. i Cathartes a. septentrionalis...:.... TAGS HO) || HS 14.5 Cathanistares tic btlteree na a ecto s os 14 ay at 16 || eaeA! Neaphron percnopterus:. 62..05./3.. nis Op 7) | lye 14 Gypogeranus serpentarius.......... 18.5 19 19.8 18.3 ——_ —— = —__—4 In considering the relative position of points upon these segments during the course of our remarks, we must consider the bony framework of the wing as drawn up alongside the body in a state of natural rest, as seen in the King vulture [Hayden’s 12th An. Rep't, pl. 15, fig. 105]. The head of the hwmerus is bent not only downward, but anconad, the reverse being the case in the distal extremity of the bone; these deflections, gentle as they are, and extended to a certain share of the shaft, give to this segment, both from superior and lateral aspects, the usual sigmoidal curvature. At the proximal extremity we find a well developed “ greater tuberosity ” in the form of the ordinary smooth convex and curling facet for the glenoidal cavity of the shoulder; below this occurs the tuberous and projecting “ulnar crest”? or “lesser tuberosity ” overhanging a large subcircular fossa, at the base of which we note the many pneumatic perforations, to allow the entrance of air at this end of the bone. The radial crest occupies about one third (Gyparchus) ortmore (Gathartes a. septentrion a lis) of its usual site on the superior aspect of the shaft, proximad, ex- hibiting all of its most common points of interest. It is quite vertical, turning outward but very slightly, and strongly marked by elevated muscular lines; this crest terminates over the greater tuberosity in a special broadened prominence, the continua- tion of its platelike portion beyond. From a dilated humeral head, we pass to a smooth and even shaft that presents but little for our examination; it is elliptical on section throughout, the long or major axis being vertical, while below and nearly 42 NEW YORK STATE MUSEUM midway between the extremities we observe a minute nutrient foramen that pierces the bone from before backward. Nearing the distal end of the humerus, the shaft gradually expands in a vertical direction, to support at its termination all of the characters generally found there; these, as in the case of those at the proximal extremity, possess the ordinary ornithic patterns. The external condyle is raised above the bone as a tuberous projection for muscular insertion ; both internal and external condyles are produced anconad to form outstanding and lateral boundaries to a shallow olecranon fossa, into which pass longitudinal muscular groovelets. Beyond the prominent and strongly developed “ oblique tubercle” and “ulnar convexity,” we find in all of these birds a triangular depression on the palmar aspect of the bone, which lodges the pneumatic perforations already referred to. These bones are very much alike in their general characteristics among these vultures, there being no very decided points of difference in them beyond their size; this applies pretty generally to the remaining bones of the pectoral limb. On the palmar aspect of the bone, at the base of the greater tuberosity, in Gyparchus, we find a deep pit that is not observed in the humerus of any other member of this family, though its site is marked in all by a very shallow depression. In the condors we find the radius straight and nearly parallel with the ulna; particularly is this the case in Gymnogyps, where for the distal two thirds of its extent the interosseous space is of nearly an equal width; on the other hand, the bone is very much bent in Cathartes a.septentrionalis, but here it corresponds with a corresponding curvature of its fellow, and little change is ex- perienced in the interosseous space. As a rule, the shaft of the radius is subtrihedral in form throughout its length, this being due to some extent to the prominent muscular lines on it. A transverse facet occupies the entire extent of the distal aspect of its expanded outer end, and articulates as usual with the radiale of the wrist. The facet for the oblique tubercle on the humerus is seen to be an elliptical concavity, placed vertically, with a broad facet to its outer side for the ulna. ; One of the features of the ulna is the double row of papillae down the shaft for the quills of the secondaries. At its proximal extremity the olecranon is but feebly produced, while inferior to this point we find in the ulnae of all the Cathartidae a long elliptical de- pression, that is quite characteristic, and is absent in Neophron, and the majority of the Falconidae. Beyond this locality the shaft soon OSTEOLOGY OF BIRDS 43 assumes the subcylindrical form, becomes gradually smaller in caliber and articulates distally, as usual, with the u/nare of the car- pus. Gathartes a: septe n - Hireon alis. witht Neophron (pe reno p ter us. we ob- serve that, although the measurements of the segments of the pectoral limb are very nearly alike, the latter bird has a longer tarsometa- tarsus in comparison, even where the femur and tibia are nearly as in the first; here again we find in this Old World vulture a balance among the segments of this extremity that simulates the Falconidae. 48 NEW YORK STATE MUSEUM The femur is so bent that a longitudinal line drawn along its anterior surface is convex outward, the greatest curvature exist- ing at the junction of middle and lower thirds of shaft. -The- anion is- very intimate at the lower extremity in the skeleton of Sarcorhamphus. The tibiotarsus has a large cuboid head, but the undulating articular surface at its summit is not profoundly impressed by condylar de- pressions, for the trochleae of the femur, and, indeed, the pro- and ectocnemial ridges are but feebly developed; the latter is produced fibulaward as a strong though blunt tuberosity, shielding the superior tibiofibular articulation in front. The cnemual crest above these pro- cesses is likewise low and not raised to any extent above the general articular surface to which it forms the anterior boundary. A section of the tibial shaft, made anywhere between the distal extremity and the fibular ridge, shows it to be broadly elliptical, and the entire shaft is bent so as to be convex anteriorly, concave throughout its length posteriorly ; it expands transversely as it ap- proaches the distal extremity, where we find the usual points for examination found in the vast majority of the class. A broad and strong osseous bridge is thrown obliquely across the groove that is the continuation upward of the intercondyloid notch, to retain the extensor tendons. The trochleae are uniform in outline, placed in anteroposterior and nearly parallel planes, the fibular one being the broadest anteriorly. The notch separating them is deepest just below the bony bridge for the extensors in front, while behind it is not carried very far up the shaft and becomes very shallow, the trochleae apparently running into one common surface. Whe bones of-the lezof Neophron percnopterus. are very similar to those found in the Cathartidae; the principal differ- ences seem to be that the pro- and ectocnemial ridges at the prox- imal and the trochleae at the distal extremity are placed rather farther apart; the bony span to hold the extensor tendons is the same. We mention this fact because in some of our American hawks and caracaras (Tinnunculus, Polyborus ) it is found to be double, i. e. the bridge above is thrown across a wider tendinal groove in these birds, and from the lower margin of the span another bony piece is joined that is carried down to the intercondy- loid notch. This arrangement gives one opening above and two below, one on either side of the last bony span mentioned. 50 NEW YORK STATE MUSEUM Passing to the tarsometatarsus, we_observe that among all of the American vultures it has a tuberous /ypotarsus, with a raised crest extending from it below, that soon merges into the general sur- face of the shaft upon the posterior aspect. In Cathartes this hypotarsial process is sharply grooved in a vertical direction be- hind. This is also the case in Catharista; the King vulture has the process broader transversely, the grooving shallower, with its outer and posterior margins slightly produced. This condition 1s still further advanced in the condors, while in Neophron we note that it has been carried still further, so much so that the mid vertical groove is now a broad concavity and the lateral productions appear as separate and rounded processes. Its form is quite dif- ferent in many of the Falconidae. Gypogeranus has the hypotarsus very much as we find it in Cathartes a, septentrio- nalis, only rather longer for its width, which is what we might expect in the skeleton of this bird of a stiltlike tarsometatarsus. A tough piece of cartilage is placed over this process in the Cathar- tidae, through which several of the flexor tendons pass. The summit of the tarsometatarsus presents two lateral concavities with a median anterior rounded tip, all for the accommodation, in the articulated skeleton, of the trochleae of the tibiotarsus. Horizontal sections made at almost any point of the shaft are more or less parallelogrammic in outline, and this portion of the bone is markedly straight in all of these vultures, for we know that in many of the Falconidae, and the condition is slightly observable in Neophron, that the tarsometatarsus is often more or less bent in the reverse direction of the tibia above. Upon its anterosuperior sur- face the shaft of the tarsometatarsus is very much scooped out in the longitudinal direction. Two foramina pierce the shaft at its upper part, and one of them appears upon either side of the hypo- tarsus posteriorly. Distally, the shaft is pierced anteroposteriorly by the large foramen for the anterior tibial artery, the aperture occupying its most usual site. The three trochlear processes that project from this bone distally are large and well separated from each other, the mid one being the largest, standing out in front of the others and possessing a very decided median grooves that passes clear round its entire surface; this feature is usually absent on the lateral processes, of which the outer is the smaller; these are placed slightly to the rear of the middle one, particularly in the condors, least of all in Catharista, in which vulture all three are nearly in the same transverse plane. The concave facet for the os metatarsale OSTEOLOGY OF BIRDS 51 accessorium is more than usually distinct, and this bone in the recent skeleton is attached after the common rule by ligament merely; it is twisted upon itself, rather long, but not so long in proportion as in Neophron, and supports its ordinary toe, of a joint or phalanx and an osseous claw. Perhaps there is no better way of calling the student’s attention to the points of interest that are to be found in the feet of these birds than by comparing such a vulture as Gyparchus papa, that has represented in these parts all of the characters of the Cathartidae, with Neophron percnopterus, that as far as we know possesses in its foot all of the characters of the vul- turine birds of the Old World. The joints of the toes follow the usual avian rule of 2, 3, 4 and 5 segments to the first, second, third and fourth toes respectively. In the first or hind toe of Gyparchus, and in all of the Cathartidae, the proximal joint is long and about equally dilated at either extremity, while in Neophron the end that articulates by its concave trochlear surface with the os metatarsale accessorium is very much expanded transversely, while at the same time it is compressed from above downward. The bony tubercle found at the under side of the proximal extremity of all of the claws is quite an insignificant affair in our vultures as compared with the protuberance we find in Neophron, and, moreover, the claws are very much more curved in this latter bird than they are in the Cathartidae. The proximal joint of the inside toe of Gyparchus is long, having all the characteristics of the other long segments of the foot, while in Neophron it is a markedly short and irregular bone, having, to be sure, its ordinary articular surfaces. one at either extremity. This difference can be made more evident by simple measurement; the first and second joints of the inside toe of Gyparchus measure respectively 2.2 and 2.5 centimeters in Neophron percnopterus, the same segments .7, and 2.4 centimeters, respectively. It is very interesting for us to know that in this matter of the shortening of the first joint of the inside toe, Neophron follows all of the Falconidae or their American repre- sentatives that we have been able to examine. Differences in the hind toe are not striking, the segments in both birds being long and proportionately balanced, but in the outside toe again we discover a leaning on the part of Neophron towards the Falconidae, while Gyparchus, in common with the rest of its well marked family, still exhibits a proportion in the lengths of the podal phalanges; this time it occurs in the second and third joints of the toe in question. These we will also compare by measurement: in Gyparchus, first, 52 NEW YORK STATE MUSEUM second, third and fourth segments measure 1.8, 1.4, I.1 and 1.6 centi- meters, respectively ; in Neophron the same segments measure, in the same order; 1:2,9.5, 4; and 1.5 centimeters: A number of the characters which | have pointed out as being found in the skeletons of the Cathartidae will probably be touched upon again, when the osteology of the American genera of the Falconidae is reviewed. To this subject we will now at once pass, and at its close, a complete, though brief, synopsis of the skeletal characters of the Accipitres will be presented, together with a few remarks in reference to some of their affinities. FALCONIDAE As an introduction to a study of the skeletology of this family, as it is represented in our United States avifatina, I will here re- publish my account of the osteology of Circus hudsonius. and in the remainder of this treatise compare the characters of the skeleton of this harrier with such other skeletons as are at hand representing the hawks, eagles, kites and others. By such a method it will be quite possible to very fully present all of the more important characters of the skeletons of our Falconidae, and the work may be completed by a synoptical table of characters. In reproducing my Osteology of Circus, there will be but few, if any, changes made in the original memoir, and the only disadvantage this may occasion will be, perhaps, a repetition of statements in a few instances, if this may be considered a disadvantage. I have a num- ber of skeletons of this harrier whose osteology we will now pro- ceed to describe. Skull. In dealing with this part of the skeleton of Circus, I will take into consideration only the skull of the adult individual; mak- ing no attempt to give exact definitions of the boundaries of the several elements of the skull, a thing which is only possible in im- mature specimens.! We observe upon lateral view |fig. 19] of the skull of this harrier that the premaxillary is produced downward anteriorly into a sharp pointed hook. The upper boundary of this, strongly convex, forms a little less than half of the culmen, commencing as it does at the apex of the osseous beak, and extending back to where the nasal processes of the bone commence. Here the premaxillary presents 1 This question will be touched upon, further along, in the skull of another hawk, the writer having in his private cabinet a fine series of skeletons of nestlings of Falco sparverius. OSTEOLOGY OF BIRDS 53 another convexity as it passes over the nostril to gradually terminate, where its nasal processes articulate with the frontals in the median line. The opposite or posterior margin of the hook above mentioned is likewise convex anteriorly, and its margin is produced backward, forming the border of the dentary process of the premaxillary; it again becomes convex from above downward. ‘This latter convexity forms quite a perceptible swell in the bone, just before it receives the insertion of the maxillary. The osseous nostril is elliptical in outline, and these two opposite apertures are separated from each other to the extent shown in the figure, by an osseous nasal septum. This septum has a transverse partition, joining, but not rising above the middle of the nasals, and merging into the above mentioned longitudinal one, which latter is then produced backward nearly to meet the ethmoid, while an- teriorly it gradually slopes downward and forward by a gentle convexity to merge into the margin of the anterior third of the osseous nostril. As is the case in nearly all birds, the posterior boundary of this nostril is formed by the nasal, which bone in this species has become thoroughly incorporated, so far as its sutural borders are concerned, with the other elements with which it comes in contact, with the exception of the nasal process of the premaxillary [fig. 19]. We are likewise enabled to see upon lateral view the extensive ma.il- lopalatines of this harrier. These very delicate bones are of a highly spongy texture here, and rise up nearly as high as the ethmoid. Anteriorly they attach themselves both to the nasals and the internasal septum. As they are produced backward they le nearly parallel to each other, an interspace existing of about two millimeters into which the vomergextends in the median plane. Be- low, their tissue is a little denser, their borders are rounder, while they merge into each other anteriorly on this aspect with the pala- tines and premaxillary [fig. 21]. Their union with each maxillary is through a horizontal plate, which is not perforated by any foramina. The lacrymal of Circus is quite a large bone, as it is in many of the Falconidae. It articulates with the frontal alone, on an extensive facet situated on the extreme anterior and outer mar- gin of that bone, just where it is overlapped by the nasal. From this point the lacrymal throws out, horizontally, being at the same time directed somewhat backward, a broad “ superciliary process ” [fig. 20], while it sends downward a flattened and much smaller 54 NEW YORK STATE MUSEUM process, concave in front, convex posteriorly, which touches by its apex the maxillary bar [fig. 19]. / At the posteroexternal margin of either lacrymal there is always — to be found a free “ accessory piece’ consisting of a small osseous scale, horizontally attached to the bone by semiligamentous tissue. The lacrymal of Circus is a thoroughly pneumatic bone, and- presents for examination several confluent foramina, which open on its inner aspect at the junction of the superciliary and descending processes. | The anterior border of the superior half of the ethmoid is broad, flat, and somewhat thickened, and this part of the bone reaches forward beyond the aliethmoid plates, to form a substantial base upon which the frontals and premaxillary rest. Anteriorly, the lower margin of the ethmoid is sharp where it joins with the rostrum. The aliethmoid plate is conspicuous on lateral aspect of the skull. Its posterior surface looks upward, backward, and outward, the plane being reversed for the anterior surface.- In outline it is an oblong plate, which is quite true for its lower and free end, while the opposite end is broader and merges with the mesethmoid. At its superior and inner angle, just beneath the frontal, it is pierced by an elliptical foramen for: the passage of the olfactory nerve; beyond, it develops a small bony canal for its further protection. The interorbital septum presents near its middle one large, ellip- tical vacuity, with the major axis of the ellipse about parallel with the zygomatic bar. In the recess of the angle between this sep- tum and the frontal bone, we find the double groove for the lodg- ment of the olfactory nerve, the grooves commencing directly in front of the olfactory foramen, running parallel with each other quite up to the opening for their passage through the aliethmoidal plate. The zygomatic or jugal bar is very slender in Circus, and the sutures of its original elements are quite obliterated. Its quad- rate end develops at right angles a peglike process, to articulate in a corresponding pitlet in that bone. The maxillary or anterior ex- tremity has already been sufficiently described. Its relations with the palatines and maxillopalatines are well shown in figures 19 and er: j The superior margin of the orbit is rounded, but as this proceeds backward it soon becomes sharp, a condition it retains to the very tip of the sphenotic process. OSTEOLOGY OF BIRDS 55 At the back of the orbit the wall is broad and gently concave throughout; it being pierced at its lower: and inner angle by a circular optic foramen, and the foramina more external to it are quite distinct from each other, which is by no means the rule gen- erally among birds. The outline of the olfactory foramen leading into the brain case is very irregular, and the wall in its immediate neighborhood is thinned to the extent of perforation in one specimen before me, while in another two minute foramina occur, just large enough, on either side, to admit the passage of the nerves, and the aforesaid perforation is much smaller. Quite an extensive osseous flap is thrown out to shield the opening to the ear behind. This latter aperture is comparatively very large, the opening being fully equal _in size to the corresponding one in a specimen of Falco r. gyrfalco from Alaska, which I find in my collection, and, as we know, a very much larger species than Circus. In the upper part of the recess, formed by this aural cavity, the double head of the quadrate articulates, the outer head with the squamosal, the inner one with the bony wall within. This bone then becomes twisted on itself, to support below the usual articular facet for the mandible, which facet is quite narrow from before backward, and rather long transversely. It presents two articular surfaces, an outer and an inner, connected by a narrow isthmus posteriorly, and separated by a shallow concavity anteriorly. The quadrate throws inward a stumpy orbital process, the an- terior surface of which lies in the same plane with the general an- terior surface of the bone, it being directed upward, forward and outward. On the posterior surface of the quadrate we find a - longitudinal depression coming down from between the two heads mentioned above, which harbors one of the pneumatic foramina, the other being found at the base of the orbital process on this aspect. The peculiar form of the cranial vault with the bulging supra- occipital prominence, should be noted on this lateral aspect of the skull. Upon a superior view of the skull of Circus [fig. 20], the principal points to be observed are the position of the elliptical, osseous nares; the direction of the craniofacial suture, which in this harrier is not drawn directly across in a transverse line, as it is in Falco sparverius, for instance. It is to be observed also that the sutural traces of the nasal processes of the premaxillary are quite distinct in adult skulls, while in some falcons they are entirely 56 NEW YORK STATE MUSEUM obliterated. The distance between the superorbital margins is very narrow, and a shallow, longitudinal, median groove courses between them, nearly as far in a backward direction as the supraoccipital prominence. The parietal prominences are smooth and somewhat 19 Left lateral view of the skull and mandible of Circus hudson ius Fic. Fic. 20 The same specimen from above; mandible removed 1 The same seen from below; mandible removed Fic. All these figures are life size from nature, Fic. 22 The hyoid arches from below. from an adult female subject collected by the author in Wyoming (1878). prominent. Venous grooves are seen running over them and lead- ing to minute foramina just within the orbital margins. The superciliary processes of the lacrymals are well seen upon this view, and it is to be noticed that their outer extremities support OSTEOLOGY OF BIRDS 57 “accessory pieces ’”’ as in some other falconine forms; moreover, these bones are very loosely articulated with the frontals on either side, and they are sure to come away in the course of ordinary maceration. From above we can also see the aliethmoids and the anterior margins of the quadrates with the zygomatic bars leading from them. The maxillaries show also upon this view, just beyond the lacrymals. One of the most striking features upon basal view of the skull of Circus is, how all the bones lie nearly in the same horizontal plane, this plane extending from the posterior margin of the foramen magnum to the descending hooklike process of the beak formed by the premaxillary. This feature is quite characteristic of some of the other genera, but not to the extent as seen in this harrier. Just within the point of the beak are four small foramina, and these openings are seen in other falconine species. Immediately behind them we see in Circus the space where the palatines and maxillopalatines merge into the premaxillary. On either side, and external to this, is a foramen formed by the bones surrounding it — the maxillary, the palatine and the dentary process of the pre- maxillary. The major part of the palatines lie in the horizontal plane; they are broad behind, where they are marked on their inferior surfaces with shallow depressions, to run out into narrow bars anteriorly. The interpalatal space is broad, being fully three millimeters across its narrowest part. In this space we see the vomer and the maxillo- palatines. A small part of the palatines posteriorly curve upward, affording by their firmly united superior surface a concave groove to ride upon the rounded surface offered by the anterior half of the rostrum, while beyond this they anchylose in the median line with the vomer [fig. 23]. The articular heads of the palatines also rest upon the rostrum, side by side, with their facets looking almost directly backward to articulate with the pterygoids. The vomer [fig. 23] can best be studied an a longitudinal and vertical section of the skull, passing very slightly to one side of the median line. This I have been enabled to perform on one skull by means of an exceedingly fine jeweler’s saw. The appearance upon the cut side of such a section is well seen in the figure referred to, where the position of the vomer, there marked v, can be easily observed. It is seen to be a thin lamina of bone, flattened from side to side, and shaped much like a long S. Its anchylosis with the 58 NEW YORK STATE MUSEUM united palatines seems to be complete, while its anterior extremity is pointed and free. The maxillopalatines have already been fully described above, their relation to the internasal septum and the vomer can also be seen in figure 23. The pterygoids are a very slender pair of bones in Circus; an- teriorly they articulate with the palatines and the rostrum of the sphenoid, although they fail to come in contact with each other at this point. Their posterior extremities are expanded and cup shaped to allow them to articulate with a corresponding convexity on each quadrate. They do not meet the basisphenoid by articulation with basipterygoid processes, as in the Striges. At the points, however, where such processes are ceveloped, Circus possesses a sharp pointed spicula of bone on either side, and this is opposite a Fic. 23 A vertical, longitudinal section of the skull of Circus, made nearly in the median plane, designed to show the capacity of the brain case, and the position of the vomer, v. Life size by the author from his own dissections corresponding enlarged part of each pterygoid [fig. 21]. These two projections are separated from each other by at least two milli- meters in life, i. e. the pointed rudimentary basipterygoid process and the enlargement on the corresponding pterygoid. The basitemporal and basioccipital regions are well depressed below the exoccipital regions and other surrounding parts | fig. 21]. A thin lip of bone overhangs the two openings of the Eustachian tubes, while the foramina for the internal carotids lie external and posterior to them just above the anterior tympanic recess. The foramina for the exit of the other cranial nerves that issue from the brain case occupy their usual sites and offer nothing peculiar for description. They agree with Parker’s figure of a nestling of Aecipt terns ais OSTEOLOGY OF BIRDS 59 The condyle is hemispheroidal in form, and very small; it barely encroaches upon the periphery of the foramen magnum. ‘This lat- ter aperture is nearly round, and lies quite in the plane of the basi- cranii. This condition seems to be characteristic of the Falconidae. A posterior view of the skyll of Circus presents a smooth, semi- globular surface. At its lower part, in the median line, we observe a well developed supraoccipital prominence, with a decided con- cavity on either side of it. On this view we are just enabled to see the condyle, and only the outer projections of the quadrates. Later- ally, the squamoexoccipital wings hide other things from view be- yond. Above these wings the sphenotic processes hang down. The shallow median groove passes between the parietal eminences. In the brain case we observe that the carotid openings are separate, being some distance apart in the pituitary space |fig. 23]. The wall covering the anterior semicircular canal is much raised, while beyond it the usual group of foramina for the exit of the seventh (the vagus) trifacial division of the fifth and other nerves are seen. The fossae for the lodgment of the several encephalic lobes are very deep, and this condition is hightened by an ossification of the tentorium, which divides them, for some little distance beyond the inner cranial wall along the site of the attachment of that membrane. The optic nerves make their exit at separate openings, already alluded to above. The greatest amount of diploic tissue is found between the inner and outer cranial tablets, at the vault of the cavity, or that portion covered by the frontal bones, as it is in these latter that it exists. . In the superoccipital region it is quite scanty, and the cranial walls are here very thin [fig. 23]. Many of the bones in the skull of this harrier are pneumatic, this part of the skeleton when dried weighing but 38 grains (Troy), and this includes the lower jaw. The mandible may be said to partake of the V-shaped variety, and the symphysis is gently curved downward anteriorly so as to look upward and forward. Each ramus has rounded superior and in- ferior borders, and their width is quite uniform from the coronoid process to the symphysis on either side [fig. 19, 24]. Upon this aspect, too, we observe that the ramal vacuity, seen in so many birds, indeed in other species (Falco), has here been en- tirely absorbed. Every evidence of original sutural landmarks has been obliterated, and the mandible of Circus is as good an 60 NEW YORK STATE MUSEUM example as we will find anywhere among the class of a “ single bone.” One not acquainted with its composition in the nestling would never suspect anything else after careful examination. The inturned tips of either articular end are at right angles to the median plane. Each presents an elliptical pneumatic foramen just within the tip. Concave articular facets are seen, which correspond to the convex surfaces, as described on the foot of each quadrate. There is a rudimentary “ posterior articular process” present. The coro- noid process, on either ramus, is but feebly developed and only slightly elevated above the general line [fig. 24]. When articulated with the skull the superior line of the ramus ceases to be approxi- mated to the osseous superior mandible at a point on the middle of the dentary process of that bone. From this point it curves gently downward until at the tips of each mandible they are four milli- meters apart. This condition is seen in the Cathartidae also. In the hyoid arches we find that the glos- sohyal remains in cartilage throughout life [fig. 22]. The ceratohyals or “lesser cornua” are quite individualized, being simply con- nected by a transverse bar at their middles, affording the articular facet for the basihyal. This latter element 1s coossified with the basi- branchial or urohyal, the two bones forming one piece in the adult harrier. The cerato- and epibranchial elements are upcurved, slender, cylindrical rods of bone, the latter being Fic. 24 Mandible of Cir- —, cus seen from above. Life Slightly tipped with cartilage on their pos- size from nature terior extremities. Circus presents the desmognathous type of structure so far as its palate is concerned, and falls within the group Aétomorphae of Huxley. The desmognathism in Circus, and the union of its maxillopala- tines with the nasal septum takes place beyond the broad processes thrown off by the maxillaries, while the spongy parts of the maxillo- palatines are produced far backward with a narrow valley between them. The arrangement is very different in Falco, where the fusion of the maxillopalatines is entirely opposite the maxillary processes, if any- thing somewhat more posterior to them, and, after their separation, the intervening valley is much wider. OSTEOLOGY OF BIRDS 61 The inner condyle of the quadrate is lower than the outer, and at the same time the smaller of the two. Parker tells us that ‘in the Sparrow hawk distinct pterotic and sphenotic centers are developed; and the orbitosphenoids are pre- ceded by cartilage.” [Morphology of the Skull, p. 264] Axial skeleton [fig. 25]. The cup for the occipital condyle on the anterior aspect of the atlas of Circus presents a distinct notch in its superior periphery. Above it, the neural canal is a transverse ellipse, the neural arch closing it superiorly being quite broad. Below, two short processes are directed backward behind the part bearing the articular cup. The “odontoid process” of the aris is compressed from above downward, its surface being flat superiorly, convex below. The neural canal is circular, and the arch above supports three stumpy processes, the lateral diapophyses and the neural spine. Beneath the odontoid process the atlantal articular surface is a shallow con- cave ellipse, placed transversely. Behind this, the body of the bone is compressed from side to side, with longitudinal median crest, terminating posteriorly in a knoblike process. The 3d vertebra presents pre- and postzygapophyses ; the articular facets on the first being directed upward, those behind directed downward. These processes in this vertebra are united by a hori- zontal plate of bore, which lends to this segment a very solid ap- pearance not possessed by those behind it. It is pierced about the middle on either side, near the outer margin, by a minute ‘foramen. A median neural spine projects backward from the posterior border. The neural canal is cylindrical, and the arch slightly overhangs it behind, but recedes from it anteriorly. On either side of the verte- bral canal is present a minute perforation; the parapophyses having short spiculae directed backward. A median, oblong hypapophysis is situated posteriorly, directly above which is the articular facet for the fourth vertebra. It is concave from above downward, and convex from side to side, the reverse being the case in the anterior facet, which is directed downward and slightly forward. In the 4th vertebra the pre- and postzygapophyses are connected by a delicate spine; the articular surfaces on the former are slightly inclined toward the median plane and each other, the reverse being the case on the latter. The neural spine is more stumpy and has worked toward the middle of the arch; the canal is smaller and still circular; while the vertebral canals are larger, longer, and their 62 NEW YORK STATE MUSEUM lateral wall is perforated on either side by a small foramen. The parapophysial spines extend backward as far as the posterior artic- ular facet, and the hypapophysis is in the middle of the body of the vertebra. In the 5th vertebra the neural spine still maintains its position as in the last segment, but is rapidly disappearing. The facings of the articular surfaces on the zygapophysial processes are more de- cided, while those on the posterior pair are borne on projecting and diverging limbs of considerable length. The delicate bar that connected them on either side, in the 4th vertebra, is here de- ficient at the middles. Other features are but slightly modified; the hypapophysis has assumed a position just behind the anterior articular surface of the body. The neural spine of the 6th vertebra is barely perceptible, and the interzygapophysial bar is again intact as a delicate bridge. At the base of each postzygapophysis above, a little projection is seen, which occurs on the four succeeding segments; both then are obliterated. The vertebral canals have the form of a vertical ellipse, and the parapophysial spines are again shortening. Beneath, we observe that the hypapophysis has disappeared, and at its site, in the last vertebra, the carotid canal begins to form. The body of this vertebra is nearly square on transverse section. But slight modifi- cation has taken place in the 7th vertebra. The limbs of the postzygapophyses are shorter; the connecting bar is still intact; the neural spine has entirely disappeared; and the carotid canal is deeper and narrower. In the Sth vertebra the interzygapophysial bar is once more in- complete, while the changes taking place in the last vertebra are be- coming better marked. Sharp lateral processes form the walls of the narrow carotid canal in the oth vertebra, and the vertebral canals are nearly circular and increasing in caliber. The parapophysial spines are nearly as long as the body, while the vertebrae are now beginning to be shorter and heavier. The anterior pair of articular facets look upward and inward, the reverse being the case with the hinder pair. A tuberous neural spine and hypapophysis make their appearance in the roth vertebra, the latter being in the middle of the body. Para- pophysial processes are shorter, though more pronounced, while the carotid canal has ceased to exist. The general form of this verte- bra is cubical. OSTEOLOGY OF BIRDS 63 In the rrth vertebra the neural spine is more lofty and hooks for- ward; the spine beneath forms a low median crest nearly as long as the body of the vertebra. The vertebral canals are still increas- ing in caliber. Quite marked changes have gradually come about in the r2th vertebra. The neural spine is very pronounced, while the hypapophysis is shrinking again in importance. In the parapophy- ses the form of the diminutive rib begins to be suggested, accom- panied by a corresponding enlargement of the vertebral canals. On the centrum, the articular facets are larger, and the anterior one, especially, deeper. The neural canal, still circular, is here larger than we found it in the axis. It seems to have the least caliber in the 6th vertebra. In figure 25, the anterior vetebra shown is the 13th and it de- parts very markedly from the last one described. Its neural spine now becomes a high quadrate crest nearly as long as the centrum of the bone. . The transverse processes are heavier, and the bases to the zyga- pophyses very substantial, with little change in the direction of the facets. A rudimentary free rib has made its appearance, the body of which is no longer than its neck. I should have noted a pneu- matic foramen on the lateral aspect of the centrum of the 12th vertebra; it is still larger here; is seen in the 14th; largest of all in the 15th; very minute in the succeeding one; and disappears in the C7 The caliber of the neural canal in the 13th vertebra is circular and large; it gradually diminishes to the 19th, where it is just a little more than half the size. The centrum of the 13th vertebra is broader than it is deep, and this segment is quite short from before, backward. Below, a tri- cornute hypapophysis is beginning to be developed. In the r4th vertebra the neural crest is a little longer but no higher; the trans- verse processes are still more spreading, while the free pair of ribs are now quite long, though they do not reach the sternum, or rather are not met by costal ribs. They are devoid of epipleural append- ages. The centrum is evidently becoming narrower and longer, and this contraction and lengthening gradually continues through the 19th or last free vertebra we find before reaching the pelvis, in which the centrum is twice as long as it is wide. The articular facets also in- crease proportionately in size; the periphery of the posterior articular facets on the centrum of the 19th vertebra is fully double the cir- 64 NEW YORK STATE MUSEUM cularity of its neural canal, the measurement for the latter being taken over the middle of the centrum. Fic. 25 Right lateral view of a part of the axial skeleton of Circus hud- sonius, showing the shoulder girdle, dorsal division of the vertebral column, the sternum, pelvis, caudal vertebrae, and pygostyle. The parts are all in situ. This figure shows well the posterior and detached portion of the pubic element of the pelvis. Same specimen as figured in figures 19-22 and 24. Ribs of left side all removed. Life size from nature Returning to the 14th vertebra, we find the tricornute hypa- pophysis but little larger than we found it in the 13th, but an OSTEOLOGY OF BIRDS 65 evident disposition to contract at its base and project into the pleural space. A circular pneumatic foramen is found behind the transverse process on either side from the 13th to the 19th vertebra inclusive. This pair of openings is largest in the 18th vertebra, and smallest in the 13th. The “intervertebral foramina” become more circular and yet smaller as we proceed toward the hinder part of the spinal coiumn. In the 15th vertebra the neural crest interlocks at its posterior superior angle with the anterior superior angle of the neural crest of the 16th vertebra, by the arrowhead joint. This interlocking continues throughout the series, until we arrive at the pelvis, where no such joint is found to exist. The neural spines or crests through this “dorsal region” of the column become gradually lower and longer as we proceed toward the posterior extremity of the body. From the 15th to the 19th vertebra inclusive, the articular facets on the zygapophysial processes gradually change their direction to meet the requirements of the “ dorsal region”; they once more come to face directly upward anteriorly, while the reverse holds good be- hind; we observe also that the transverse processes in this series become longer and longer as we proceed in the same direction, and their outer extremities armed in each case with a single, delicate meta- pophysis which overlaps the process both before and behind it. In the 15th vertebra, now under consideration, the hypapophysis loses its tricornute character, and the short pedicle merely supports a circular disk, with its inferior surface directed slightly forward. This pedicle in the 16th becomes longer, and the disk becomes an ellipse, placed longitudinally upon it. The hypapophysis on the 17th vertebra dips well into the pleural cavity as a laterally com- pressed hook with slightly dilated apex. It is truly claw shaped in the 18th vertebra, though still compressed from side to side, to be entirely absent in the roth. In Circus all the vertebrae are freely articulated upon each other, from atlas to the one that first anchyloses with the ilia; in Falco sparverius, however, from atlas to 13th inclusive, are free, while 14th to 18th are thoroughly fused into one bone, the outer angles of their diapophyses even being united by anchylosis. In this common “ dorsal” piece of the Sparrow hawk the two leading vertebrae support hypapophyses. These have also fused together, leaving only a circular foramen between them. The roth vertebra of this little falcon is free and articulates with the posterior S) ‘ 66 NEW YORK STATE MUSEUM one of the consolidated bone in question, and behind with the first one of the pelvis. The 15th vertebra in Circus has a pair of true ribs, i. e. they are connected with the sternum through the intervention of costal ribs or haemapophyses, the two being freely articulated. This pair of pleurapophyses also has unciform appendages, that on either side anchylose on the lower third of the rib, their apexes being d1- rected upward. The facets for the heads of this pair of ribs are upon the anterior margins of the neurapophyses, just above the centrum of the vertebra. This position of these facets obtains for the remainder of the series of articulated pleurapophyses. The facets for the tubercles are at the ends of the diapophyses and look directly downward and outward throughout this region. The vertebral ribs of the 16th to the 19th vertebra inclusive be- come gradually longer as we proceed backward; they all bear large anchylosed unciform appendages, with their apices directed backward, of a form shown in figure 25. ‘They are laterally com- pressed and offer large articulatory facets for the costal ribs. The sternal rib of the 15th vertebra, the first of the series, articu- lates high up on the costal process of the sternum. It is short and straight. As we proceed toward the pelvis we find them ‘becom- ing gradually longer, flatter from side to side, and more curved upward, their convexities being below. They articulate with the sternum by extensive transverse facets [fig. 25]. The two leading vertebrae of the pelvis each have a pair of ribs also, that in no way differ from those that I have just described, excepting that the last pair is without fully developed unciform processes. They otherwise simply continue the series, and it ts evident that the arrangement presents seven pairs of pleurapophyses, which are connected with the sternum through the articulation with an equal number of pairs of haemapophyses, which in their turn articulate with the costal borders of the sternum by their transverse facets. Both the true and costal ribs of this hawk are pneumatic. We will now for a moment leave the vertebral column proper and pass to the consideration of the sternum [fig. 25, 26]. In outline, the general form of this bone in Circus, viewed from above, is a parallelogram. Its superior or dorsal surface is deeply concave, accompanied, of course, by a corresponding convexity of the pectoral aspect. The middle of the median line above presents a row of pneumatic foramina leading to the keel. Similar openings occur also on the interfacial spaces on the costal borders; in groups OSTEOLOGY OF BIRDS 67 just within the costal borders and the anterior border of the body; and at the bases of triangular pits, one of each, wines occupy the inner aspects of the costal processes. The hinder border of the sternal body is gently concave, and in the specimen in hand the right side is pierced. by two foramina, while only one occurs on the left, as shown in figure 26. In many specimens there is but one foramen upon either side, and occasion- ally one or both of these may be very small indeed. A specimen in the collections of the United States National Museum (no. 9383) marked Circus jardini shows the sternum to be entire save a pin hole foramen on the right side. It is also peculiar in having Fic. 26 Fic. 26 The sternum of Circus, viewed from below. wherein the sternal foramina are exceedingly small, and I should not be at all surprised to find a sternum of this hawk lacking these foramina entirely. Fic. 27 Heads of scapula, clavicle and coracoid, inner aspect, showing their mutual relations. s, scapula; cl, clavicle; and c, coracoid. Same specimen as figures 24-26. Life size from nature. I have specimens before me 19-22, the carinal angle dilated, and pneumatic fossae on the inner aspects of the costal processes. The sternum of Falco sparverius has a large elliptical foramen on either side, whose peripheries so far encroach upon the posterior margin of the sternal body as to slightly absorb it at the point of tangency. In Falco r.colum- barius these foramina are well within this border. But one pair of muscular lines presents itself upon the otherwise smooth ventral surface of the sternum of Circus. Two of the lines are seen on each side of the keel [fig. 26]. The carinal angle is rounded, the anterior border of the keel being concave, while the 68 NEW YORK STATE MUSEUM inferior one presents a graceful convex curve. Posteriorly it terminates at the apex of a triangular smooth surface, the outer basal angles of which are opposite the foramina in the xiphoidal extremity [fig. 26]. The line of union between keel and body is rounded, being concave outward. Marked differences occur in the manubrium of the Falconidae; here in Circus it is a stumpy process, generally inclined upward, having a sharp median edge below and a triangular anterior surface. Among the Falcons (Falco r.columbarius), it is a narrow spicula of bone, directed forward and upward; but what is most singular, there exists in these birds a second process that springs in the median line from the border of the body above. These two pro- cesses have the coracoidal grooves between them. The grooves for the coracoids decussate in Circus, their inner ends terminating in points; they decussate still more in Falco, where their inner ends are rounded. Sucli a decussation of the coracoidal beds is likewise to be seen in the herons, as in the genus Ardea. : In the specimens of all the Falconidae before me, it is the right coracoidal groove that is the anterior one, and overlaps the superior surface of the base of the manubrium. As well as I can remember such is also the case with the herons. -Returning now to the spinal column, we find that the 20th verte- bra of Circus becomes anchylosed beneath the ilia. Its broad neural spine has fused into one piece in common with the others that ex- tend back as far as the sacrum; its diapophyses are half covered by the anterior iliac borders, and these with the next vertebra be- hind show the facets for the two pair of ribs already described above, which are here overarched by the ilia [fig. 25]. The anterior aspect of the 20th vertebra presents all the require- ments for articulation with the one next beyond, in its prezygapo- physes, and in its centrum. Metapophysial spines, however, are only thrown back by the segment before it, while the locking of the neural spines does not take place. This description of the 20th vertebra brings us to a point where we must needs take into consideration the pelvis of Circus [fig. 25, 28]. Upon superior view of this bone [fig. 28] we observe that the neural spine or rather its upper surface projects forward as a broad process between the ilia, and is roundly notched anteriorly. The common top of this neural spine for nearly the entire length of the pelvis is smooth and presents little or nothing to indicate where the OSTEOLOGY OF BIRDS 69 divisions among the vertebrae take place. The parts of the last vertebra, that became anchylosed with the pelvis, are easily made out. Very minute interdiapophysial foramina may pierce this region; others are but indicated by minute dots. Along the mid region, the ilia rise above these fused vertebrae in sharp crests, which crests in being produced backward form the outer margins of these pelvic bones where they constitute the postacetabular sur- face. The “ilioneural grooves” are closed in, but they exist as capacious “ ilioneural canals ” beneath the ilia anteriorly. Each ilium has a rounded anterior border, which presents a slightly raised emargination just within it. The preacetabular surface of the ilia is fully twice as long as the postacetabular, and its superficies is also double in extent [fig. 28]. In each bone the former surface, anteriorly, is first directed up- - ward and only slightly outward; as it passes backward it faces almost directly outward, a direction which it maintains for the rest of its extent. The postacetabular surfaces of the ilia are confined to two elliptical areas, which roof over the ischiac foramen on either side, and the direction of whose surfaces is upward. Upon lateral view of the pelvis [fig. 25], we see a circular acetabulum with a very deficient base, the periphery of the inner circle being but little smaller than the outer rim of the cavity. The antitrochanter is long and narrow. The plane of the ischiac foramen is directed downward, backward and outward, and this aperture is completely overshadowed by the ilium. The ischiac area is generally concave and triangular, the apex of the latter being directed backward. Considerable interest attaches to the condition in which we find the pubic bones in Circus. The anterior limit of one of these bones, after it leaves the acetabulum, closes in the obdurator foramen quite completely, but does not pass beyond. Then occurs an interval, be- low the lower margin of the ischium, which in life is filled in by ligament, that connects the floating part of the remainder of the pubic bone behind. This latter piece is simply suspended from be- neath the posterior angle of the ischium by ligament, not in any way connected with the anterior limb of the pubic rod, except through the means of the material mentioned [fig. 25]. I made many care- ful examinations and dissections of this bone in Circus before I was satisfied of what I saw, and that the condition existed as I have described it. In Falco sparverius the connection between 7O NEW YORK STATE MUSEUM these two separate parts of the pubic bone is through the finest imaginable bony bridge, that passes close under the margin of the lower ischiac border, and so far as I have examined the falcons it is always present in them, though sometimes almost of hairlike di- mensions. Professor Owen says: “The shortest pubis is seen in certain eagles, in which it terminates after forming the lower boundary of the obturator foramen, its extremities there projecting freely, as in figure 23 [d side view of pelvis, eagle], or being joined by liga- ment to the ischium, as in the Harpy eagle, in which it is an inch in length, whilst the ilium is six inches long.” [Anat. Vert., 2:36] I am sorry to say that at present writing I have not the complete skeleton of an eagle before me, and no pelvis of that bird. I would not be surprised to learn, however, that the skeleton that fell to the lot of this eminent anatomist to examine at the time he made the above statement was an imperfect one, and that the hinder three fourths of the pubis on both sides was lost, a thing very likely to happen were they connected to the anterior portion by a delicate bridge of bone, or entirely disconnected as we find them in Circus. It may be that specimens of Circus will be taken where the fine bony, almost hairlike, connection will be seen to join these two parts of the pubis, but so far I have failed to find one, and I must be- lieve that the condition as I have described it above is the normal and perhaps constant one. Taking into consideration the state of these things as they exist in Falco sparverius, it is very easy to conceive how such a condition might come about as we see it in Circus — the fine ligamentous span simply no longer ossifies — as whatever the original necessity was for weakening the pubis at this point it has been eventually accomplished, and ossification is now no longer extended to that part of the pubic rod at all. The free hinder ends of these bones in Circus are now completely mov- able, as any one can satisfy himself by examining these parts in a freshly killed specimen. The 2oth and 21st vertebrae seen beneath the ilia have already been sufficiently described. Posterior to them on the ventral aspect of the pelvis a considerable swell takes place in the column to ac- 1Since writing the above I have detected this condition of the postpubis in other Falconidae, and the reader is referred to my remarks about it in The Auk, Januar 1886, p. 133, where I give a figure showing how it also occurs in Buteo bore alig calurus. This figure is herewith published in the present treatise as figure 47. Prof. W. K. Parker F. R. S., tells me, too, in a valued letter I have from him, that this state of things also occurs in some of the Old World Falconidae, and in them the postpubis is occasionally aborted, “‘ which is a very interesting fact.” QSTEOLOGY OF BIRDS _ 71 commodate the sacral enlargement of the cord. This gradually con- tracts again at a point opposite the anterior borders of the acetabu- lae. The 22d vertebra throws up both parapophyses and transverse processes against the ilia. In this the next three succeeding verte- brae follow suit. This takes place at the narrowest part of the pelvis, and these processes are very stout here. In the 26th to the 29th, inclusive, the short abutting processes can not be seen upon direct ventral aspect. This is the region of the true ‘sacrum ” and the foramina of exit for the sacral nerves are here double on either side, one opening being above another. The 30th, 31st and 32d vertebrae have long parapophyses, which amalgamate at their outer extremities, where they form a powerful abutment for the pelvic walls at points opposite the acetabulae. The pelvis of this harrier is deep in all this region, that is, posterior to the 25th vertebra and in- cluding the three I have just mentioned. The pelvic bones behind grasp but two more segments of the column, the 33d and 34th vertebrae. These much resemble the anterior coccygeal ones, especially the last one. In the coccyx we find six vertebrae freely movable on eacli other, but with nothing Fie. 28 Superior aspect of pelvis of Circus; same spec- peculiar about them. The fourth and fifth imen as the last. Life size ° . f t of this series have equal and at the same ~“" time the most far extending transverse processes. The width of the last (the sixth) is about equal to the first, and the last three have bifid hypapophyses. Circus has a very broad and _ lofty pygostyle, that in the adult bird shows but few traces of its original composition. Its anterior edge is sharp, while \behind it is flattened and narrowly triangular with the base of the triangle below. I give a posterior view of this bone in the osteology of the Cathartidae above, figure 13, where it is compared with the bone as it occurs in other Falconidae. In Circus pneumaticity is partially extended to the first two free coccygeal vertebrae, but not beyond them. In the pectoral arch we find that a scapula is broad and truncate posteriorly, with its apex drawn out into a spicularform point. Its 72 NEW YORK STATE MUSEUM neck is thick and broad, being subelliptical upon section [fig. 25, 27] ; while on the articular surface it extends to the glenoid cavity, and is about half or a little more than that presented by the coracoid. Upon its under'surface, close to the line of articulation with this latter bone, we find a circular pneumatic foramen, which is constant. This line of articulation runs out to the end of the scapular process of the coracoid, but beyond this the scapula is extended as a clavic- ular process which meets the head of the furcula with greater or less intimacy [fig. 27], thus closing in the tendinal canal. The proper relations of these bones in Circus are shown in figure 27 of the present treatise. In Circus all the thoracic pleurapophyses are overlapped by the scapula, except the last two pairs, so we may. judge from this that that bone is below the average length for birds, not reaching the anterior border of the pelvis. One would hardly expect from an examination of the sternal bases of the coracoids that they decussated in their grooves, as these parts are apparently exactly alike in either bone. The inner angle is carried out as a sharp point while the outer is a stumpy process [fig. 25]. A strong muscular line marks the shaft anteriorly, es- pecially at its lower part, the shaft itself being stout and sub- cylindrical at its middle third. Just below the inner end of the scapular process, we find on the side of the shaft a long, shallow notch, which in life is spanned by a delicate ligament, thus con- verting the notch into a foramen. In some specimens this foramen is completed in bone; it may pierce the coracoid upon one side and be a notch on the other. A specimen of Circus jardini has it a shallow notch upon either coracoid [U. S. Nat. Mus. Collec. no. 9383]. In many owls this foramen pierces the wing of the scapular process of the bone near the center, as in Speotyto, where I found it transmitted a branch of that cervical nerve coming from between the 12th and 13th cervical vertebrae [see On the Osteology of the Striges, Am. Phil. Soc. Proc. 1900, v. 39, no. 164, p.-700]. The scapular process of the coracoid has already been alluded to above when describing the scapula. It is comparatively very small and shows but little on direct inner view [fig. 27]. It holds the. same position as seen in Ibycter americanus, Micras- tur semitorquatus, Buteo borealis and others studied by Ridgway, and so strikingly compared in his Outlines of a Natural Arrangement of the Falconidae. Upon the anterior aspect of the coracoid or really on the head of the bone, there is an elongated facet placed vertically and slightly OSTEOLOGY OF BIRDS 73 raised above the surrounding parts, which articulates with a broad surface of similiar form on the outer side of the expanded head of the clavicle; this latter surface looks directly backward, a special recess being made for it. The meeting of the two bones is ex- tensive and very intimate, as I have elsewhere pointed out. The rounded tuberous head of the coracoid rises but little above the broad surface of the anterior end of the clavicle, and this pro- jection arches over a recess at its inner aspect in which is hidden large pneumatic foramina that communicate with the hollow shaft and other parts of the bone. ‘ The furcula or the united clavicles are likewise highly pneumatic bones ; the foramina that enter them being found upon the nonartic- ulating surface, opposite the foramina just described as perforating the inner side of the head of the coracoid. . When the two bones are im situ, these two surfaces form the anterior walls of a fossa that lies immediately beyond the “ tendinal canal” and really a part of the same inclosure. Above, the clavicles are broad and articulate with the sides of the heads of the coracoids, and the clavicular process of either scapula in a manner already described. Viewed from in front they present the extreme type of the U-shaped style of the bone, the internal periphery of the arch being nearly a semicircle. The bones are compressed from side to side, and diminish in breadth as they ap- proach the point of union below. Here the clavicles support a small tuberous hypocleidium, which, owing to the backward curvature of the fourchette, is about opposite the coracoidal beds on the sternum.