ON THE OSTEOLOGY OF THE PIGEONS (COLUMBK). DR. R. W. SHUFELDT. INTRODUCTION. DURINGthe past twenty years I have carefully examined and compared the skeletons of upwards of twelve hundred species of birds, and read a great deal upon what has been printed on the osteology of this interesting group of vertebrates. Many families and genera are represented by the material I have examined, the most of it being from the representatives of the United States avifauna. My observations have been written out and illustrated, the whole making a manuscript work of about twenty-five hundred pages, with over five hundred figures. In November, 1899, Professor C. 0. Whitman of the Uni- versity of Chicago, who at that time was making some very interesting observations upon pigeons, asked me if I could not furnish him with a memoir upon the osteology of that group (CoZu~zlz6~)for the JOURNAL OF MORPHOLOGY.As my chapter in the aforesaid manuscript work on the skeletology of the pigeons had never been published, I soon ascertained from him that it would be quite acceptable for the purpose he had proposed. To copy the original chapter was by no means a light task, but it was cheerfully undertaken, and in the most painstaking manner completed, by my wife, who is ever ready to assist me in my work in such matters. My sincere thanks are extended to her here for the promptness with which the assistance was rendered, especially as it came at a time when a very formidable work of mine now in press was engaging my entire attention. Notwithstanding this, by the aid of my camera and drawing pen I reproduced all of the original plates and figures. Our labor will not have been in vain, however, 487 438 SHUFELD T. [VOL. XVII. if this brief account of the osteology of the group proves to be of any service to those laboring upon the structure of birds. R. W. SHUFELDT. WASHINGTON,D. C., Dec. zz, 1899. COLUMBE. SUPERFAMILIES. FAMILIES. SUBFAMILIES. Didoidea Dididz Geouridz Columboidea Carpophagid= i Columbidze { Didunculinae Existing pigeons the world over form a very well circum- scribed suborder of birds, for the most part quite homogene- ous in their morphology. In studying their osteology I have read the various accounts extant upon the remains of the dodo (Dia'us impus) ; skeletons of DiduncuZus stngirostris (U. S. Nat. Mus. Coll.), of Pterocles arenarius (U. S. Nat. Mus. Coll.), and sterna of Syrrhajtes (for which I have to thank Professor A. Newton, F.R.S.) have also been examined by me. Much of the literature and figures have also been looked over, and the skeletons of a great many genera and species of existing Columbae examined and compared. Our United States pigeons are all members of the family Columbiak, and consequently are all true columbine birds. They represent the genera CoZumba (with three species), Ectopistes (one species), Zenaidura (one species), Zenaidiz (one species), EngwptiZa (one species), MeZoopeZia (one species), and CoZambigaZZina, ScardafeZZa, Geotygon, and Stamms, a11 with one species each. Skeletons of most of these genera are at hand at the present time, but I am obliged to rely upon the works of others, of which there are a number of very reliable ones, for the osteology of Cobmba. I have by me, however, skeletons of the common domesticated pigeons, but they vary greatly in their characters, as has been shown by Darwin and others.' 1 Mr. J. S. Singley ,of Giddmgs, Texas, has furnished me with some good osteological material for the United States pigeons, especially in the genera N0.3.3 THE OSTEOLOGY OF TI-fE PIGEONS. 489 Professor Huxley, it is known, made a group, AZectommotpire, to include the gallinaceous birds, including in it the PteYocZia’a, while another group, the Peristeyomo@hre, was made to contain the true columbine forms, including the extinct dodo (Didus). Of these two groups Professor Huxley has said : ‘‘ The rela- tions of the Peristeyomoqh with the AZectaromo@hcz are very close. On the other side they seem to be allied with the owls and the vultures ” (P. S. Z., 1867, pp. 459, 460).‘ Newton, in speaking of the characters common to the gallina- ceous birds and the pigeons, has said: ‘(But peradventure the real lesson taught by this aggregation of common characters is rather the retention of the union of the GaiZina and CoZumh into a single group, after the fashion of bygone years, under the name, however meaningless, of Rasoyes. Failing that, the general resemblance of most parts of the osteology of the Sand grouse to that of the pigeons, so well shown by M. Milne- Edwards, combined with their pigeon-like pterylosis, inclines the present writer to group them as a suborder of CoZumbcz; but the many important points in which they differ from the more normal pigeons, especially in the matter of their young being clothed with down, and their colored and speckled eggs, must be freely admitted (art. ‘6 Ornithology,” EmycZ. Brit., 9th ed., Vol. XVIII, p. 46). Another classificatory view of this group has been taken by Coues, who in the last edition of his “Key” remarks that “the CoZumbre, as above indicated, are intended to be made conformable to Huxley’s Pen.steromo&vz plus Pterocktes. Assuming the imperfectly known extinct dodo, Didus ineptws, EngyptiZa, MeZoptZia, CoZumbgaZZina, and ScardafeZZa. The collections at this writing are especially weak in this group at the United States National Museum, but I can gratefully acknowledge Mr. Lucas’s kindness in having a specimen of Siarncenas cyanocephaZa skeletonized for me, and the loan of skeletons of the Passenger pigeon (Ectopistes), now becoming so rare, and a fine skeleton of Columhgallina passcrina, the interesting little Ground dove. 1 In characterizing his Pcrisferomorpha, and referring to the sternum, Professor Huxley says, ‘I The sternum has two posterior notches, the inner pair of which may be converted into foramina. The external processes thus formed are, as in the Akc.tbromorpha, much shorter than the internal lateral processes ” (Zuc. cit., p. 459). Evidently it is meant here the ‘Lfofourposterior processes,” and the words cxxkmal and internal have through a Za$sus caZami been transposed. 490 SHUFELDT. [VOL. XVII. to have been a modified columbine, and considering the Ptero. cZetes to represent rasorial modification of the columbine series, the order Columba may be separated into THREE groups, or suborders, DIDI, PTEROCLETES,and PERISTE~,the first two certainly, and the last probably, of a single family. The Pen&@ alone are American I’ (p. 562). By the American Ornithologists’ Union they are considered to be an ORDER,CoZ~mb~z, which is the arrangement also adopted by Mr. Ridgway in his Manual. Finally, Furbringer makes his 6‘ Columbiformes an intermediate suborder stand- ing between his orders, Alectorornithes and Coracornithes, classifying them thus : G. s. str. Pterocletes. F. Pteroclidk. Im. S. 0. Columbiformes{ F. s. str. Dididc. G* ‘* str‘ Columb;e{ F. s. str. Columbidc. They constitute in the present volume my suborder, CoZuzlmbac. Ectopistes affords us a good average columbine type, and from its skeleton we may study the osteological characters generally met with in the family. The brain-case in the skuZZ is comparatively capacious, being rounded for the most part above and behind, while its basal floor is nearly horizontal. It projects backwards considerably, being situated largely posterior to the orbital cavities and the quadrates. In outline the foramen magnum is cordate, and the condyle small, sessile, and notched posteriorly. The occipital ridge is fairly well marked, and it passes across the median, not very conspicuous supraoccipital prominence. Viewed superiorly, the interorbital area of the skull is markedly broad, being gently and uniformly convex from the parietal region to the mandibular base. These superficies are smooth and show no sutural traces. For the most part, the entire periphery of an orbit is sharp and unbroken in outline, being continuous behind with the anterior edge of the down-point- ing, spiculiform sphenotic process. The apex of this latter is well removed from the apex of the much aborted, stumpy squamosal process. Either orbit is here a capacious cavity, while the mesial septum between them is quite deficient poste- riorly and above. This vacuity merges with the large common No.3.1 THE OSTEOLOGY OF THE PIGEONS. -3.91 foramen, giving exit in life to the optic nerves, but not so with the equally extensive aperture above for the nerves of the first pair. So much for these interorbital fenestm. At the upper part of an orbit the groove for the olfactory nerve is seen to be single, and anteriorly it enters a very small circumscribed foramen above the pars plana. The pars plana and the very large Zacrywal bone fuse completely together, and to some extent with the frontal bone above them, This creates an unusually broad, entire inter-orbito-narial partition. Upon its outer border the lacrymal is broadly notched ; below it meets the zygomatic bar, and in front it is seen to be wedged in between the nasal and frontal, this wedge being another con- siderable part of the bone. In the cranium of this Passenger pigeon the tywfanic cavities are large, very open and exposed, and either one of them facing downwards, forwards, and upwards. The anterior apex of the basitemporal gives but slight protection to the mesial common aperture of the Eusta- chian tubes. Close to and upon either side of this opening we are to note an aborted basipterygoidprocess, and neither of these latter meet :he pterygoid bone opposite them.’ The rostrum in this pigeon is thickened, rounded below, and gradually tapers to a sharp point anteriorly, being fused in the latter locality with the lower margin of the mesethmoid, which here extends forwards considerably beyond the pars plana upon either hand.