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 prsemaxilla filled up 

 with spongy bone ; but no union takes place between this ossification 

 and the vomer. 



Fig. 32. 



Under view of the skull of Cormts corax. The letters as before. 



This structure (which was first accurately described and its syste- 

 matic importance pointed out by Nitzsch*) is substantially repeated 

 in the great majority of Passerine birds, though with minor modi- 

 fications, 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 poste- 

 riorly, is more rounded off than abruptly truncated at its anterior end. 



* See the article " Passerinae " in Ersch and Griiber's ' Encyclopaedie,' 1840, 

 and Nitzsch, " Ueber die Familie der Passerinen," in the ' Zeitschrift fUr die ge- 

 sammten Naturwissenschaften,' 1862. 



