OCR Text |
Show 1867.] PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. 451 maxillo-palatines are slender at their origin, and extend inwards and backwards obliquely over the palatines, ending beneath the vomer in expanded extremities, which do not become united by bone, either with one another or with the vomer. The anterior part of the nasal septum (in front of the vomer) is frequently ossified in iEgithogna-thous birds, and the interval between it and the praemaxilla filled up with spongy bone ; but no union takes place between this ossification and the vomer. Fig. 32. Under view of the skull of Corvus corax. The letters as before. This structure (which was first accurately described and its systematic importance pointed out by Nitzsch*) is substantially repeated in the great majority of Passerine birds, though with minor modifications, which I suspect will turn out to be characteristic of the na-- tural subdivisions of this great group. At present I can only mention two or three of these. Menura differs from all the rest in possessing no ossified maxillo-palatines whatever. The vomer, though broad and deeply cleft posteriorly, is more rounded off than abruptly truncated at its anterior end. * See the article " Passerinae " in Ersch and Griiber's ' Encyclopajdie,' 1840, and Nitzsch, " Ueber die Familie der Passerinen," in the ' Zeitschrift fiir die ge-sammten Naturvvissenscbaften,' 1862. |