440 PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. [Apr. 11, 



The same general arrangement is observable in the Cormorants 

 and the Pelicans ; but the inner edges of the palatine bones unite 

 for a much greater distance behind the posterior nasal aperture, 

 and a median ridge is sent down from the line of junction of the 

 palatines. These birds thus present the most extreme modification 

 of the palatine apparatus which is to be observed in the whole 

 class. 



In the PelecanidcB the inferior edge of the ossified interorbital sep- 

 tum rises rapidly forward so as to leave a space at the base of the 

 skull, which is filled by a triangular crest formed by the union of 

 the greatly developed ascending processes of the palatines (fig. 20). 



In the Cormorants, on the other hand, the inferior edge of the 

 septum is horizontal, and the crest in question is not developed 

 (fig. 21). 



In all the Raptorial birds the nasal septum is ossified for a greater 

 or less extent ; and the vertical plate thus formed joins below, by 



Fig. 22. 



Under view of the skull of Cafhartes aura. From a specimen in the Museum 

 of the Royal College of Surgeons. 



The letters as before. + The basipterygoid processes. 



