VERTEBRATA : AVES. 



577 



wards extensively developed horizontal processes ("maxillo- 

 palatine processes "), which form a large portion of the hard 

 palate. The extent, however, to which these processes are 



Fig. 322. Skull of young Ostrich, viewed from above (A), and from below (B). (After 

 Owen.) of Occipital foramen ; w Supra-occipital : eo Exoccipital ; ^Quadrate; 

 pa Parietal ; // Pterygpid process ; /Frontal ; e Ethmoid ; n Nasal ; frn Maxil- 

 lary process of praemaxilla ; m Malar or jugal bone; im Prsemaxilla; / Palatine 

 bone ; v Vomer ; / Lachrymal bone. The skull being that of a young bird, the sut- 

 ures are not yet obliterated. 



developed varies much in different birds, and on these varia- 

 tions, combined with the structure of the vomer, Prof. Huxley 

 has proposed to found the following divisions of the Carinate 

 Birds : 



I. Desmognatha. Maxillae sending inwards largely developed maxillo- 

 palatine processes, which unite with one another to form a bony roof to the 

 palate. The vomer truncated in front, small or obsolete. Ex. Birds of 



2 O 



