| OCR Text |
Show 1867.] PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. 441 direct bony union, with the two maxillo-palatines, which are sometimes scroll-shaped, sometimes greatly swollen and spongy. The vomer, sometimes slender, sometimes pretty broad, always tapers to a point anteriorly. The basipterygoids sometimes are and sometimes are not present. The angle of the mandible is not produced and recurved. Four modifications of the general type of palatine structure are observable among the Raptorial birds:- In the genera Cathartes and Sarcorhamphus the cleft between the thin and scroll-like maxillo-palatines is very deep and wide, and the ossification of the septum is small in extent, and only forms a sort of bridge over the deep and wide valley between the maxillo-palatines. The basipterygoid processes are large and articulate with the pterygoids (fig. 22). In all the Owls the maxillo-palatines are thick and spongy, and encroach upon the intermediate valley, though they never completely unite with one another across it or obliterate its upper part. The basipterygoid processes are always present (fig. 23). Fig. 23. The base of the skull of Otus vulgaris. The letters have tbe same signification as before. The inferior and internal margins of the spongy maxillo-palatines almost come into contact; but their inner faces are separated by a wide interval. * The prefrontal processes. The basipterygoid processes are not marked. In the Secretary bird (Gypogeranus) the maxillo-palatines unite with one another and with the extensively ossified septum, so as to fill up the maxillo-palatine valley. There are well-developed basipterygoid processes. |
