1867.] PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. 431 



which become thick and spongy, and so closely approach the middle 

 line that, in the Albatroses, only a very narrow cleft is left on each 

 side of the vomer. 



The front part of the vomer itself is much more strongly bent 

 downwards than in the Gulls ; and the ascending process of the 

 palatine bone is greatly produced, and becomes anchylosed with the 

 vomer. 



Procellaria gigas holds a sort of middle place between the Gulls 

 and tlie Albatroses, the maxillo-palatines being less swollen, and 

 the clefts between them and the vomer far larger than in Biomedea. 

 In this species again the basipterygoid processes are present, though 

 I have not been able to observe them in other Procellariidce. 



Fig. 13. 



Fig. 12. 



Procellaria gigantea. 



Biomedea exidans. 

 Under views of the skulls of Procellaria gigantea aud Biomedea exidans, 

 specimens in the Maseum of the Royal College of Surgeons. 

 The letters as before. 



From 



