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



In tlie Cracida the characteristic basipterygoid processes, the 

 produced and recurved angle of the mandible, and the form of the 

 palatines remain as in the last mentioned genera. But the maxillo- 

 palatines are large and scroll-like, stretching inwards, and in some 

 species (e. g. Crax glohicera) even becoming united across the middle 

 line with one another and with a small ossification of the septum 

 narium. 



All ColumbidcB (except Didus) have basipterygoid processes, and 

 are completely Schizognathous. The maxillo-palatines are larger 

 than in the ordinary Gallinaceous birds, and are elongated from before 

 backwards, and spong)^ in texture, not scroll- like. The postero-ex- 

 ternal angles of the palatine bones are rounded off; but, in most of 

 the Columbidce, their inner laminse are more prominent than the 

 outer, instead of being obsolete as in the Gallinaceous birds. The 

 basipterygoid processes are prominent and rather resemble those of 

 the Plovers than those of the last-named group. Finally, the angle 

 of the mandible is neither produced nor recurved, but is more or 

 less abruptly truncated. The vomer is very slender. 



Under view of the skull of Columba jMlumhus. The lettf r.s as before. 



Didus has no basipterygoid processes ; but the articular end of its 

 mandible resembles that of other Cohimhidce. 



Diduncidus more nearly resembles the ordinary ColumhidcB in pos- 

 sessing prominent basipterygoid processes ; but the palatine bones are 

 thick, their internal laminae being altogether obsolete. The distal 

 articular facet of the quadrate bone is elongated antero -posteriorly, 

 and nearly resembles the same part in a Parrot. The axis of the 

 fossa of the mandible which receives this facet nearly coincides with 

 that of the ramus of the mandible ; while in the other Columbidce 



