OCR Text |
Show 1867.] PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. 435 and in Didus it is nearly at right angles to the ramus of the mandible. The form of the angle of the mandible in Didunculus is quite unlike that observed in the other Columbidce and in Didus. In these respects, therefore, Didunculus departs further from the ordinary Columbidce than the Dodo does. I am indebted to Mr. E. Higgins for a skin of that singular bird Opisthocomus cristatus, from which I was able to extract an imperfect skull, the inferior face of which is represented in fig. 17. The base of the cranium and the pterygoid bones are wanting. The underside of the unossified nasal septum supports the slender vomer (Vo), which expands and becomes bifurcated anteriorly, in a manner unlike anything which I am acquainted with in other birds*. The very slender anterior processes of the palatine bones Fig. 17. Opisthocomus cristatus. Under view of an imperfect skull. Tbe letters as before. (the bodies of which are almost entirely wanting in this specimen) are overlapped by the short and broad maxillo-palatines, which remain very distant from the vomer and from one another. The angle of the mandible is slightly produced and bent upwards. These are all the birds (leaving the Cracidee aside) in which I have noticed the Schizognathous disposition of the palate, which, it must be observed, is characterized not only by the complete distinctness of the maxillo-palatines from one another and from the vomer, but by the slender and usually pointed form of the latter bone. III. Those Cuvierian Grallae and Natatores which are not Schizognathous, the Accipitres or Raptores, the Scansores, and, among the Passeres, most of the Fissirostres, all the Syndactyli, and Upupa may be termed Desmognathous. In these birds the vomer is often either abortive, or so small that it disappears from the skeleton. When it exists it is always slender and tapers to a point anteriorly. * In some of the Falcons the vomer has a nearly similar anterior termination, but its connexions are different. |