Gallino-Gralline Group of Birds. 431 



frequently than in others. On the other hand, although 

 there are no traces of these fontanelles in the Laridjc "when 

 adult, they are found in these birds whilst they are in an 

 embryonic condition, and in some genera {Chionis, for ex- 

 ample) they do not completely ossify until advanced age. 



Basipterygoid Processes. 



The presence of basipterygoid processes on the basisphe- 

 noid which articulate with facets on the pterygoids is a very 

 archaic character. They are suppressed in the embryos of 

 many Passerine birds, but are present in all others. In all 

 Passerine birds, and in half the remainder, they are absorbed 

 before the bird becomes adult ; but in the other half of the 

 non-Passerine birds, and in all the Ratitae, they are always 

 present. They also occur in the lizards and some of the 

 snakes. 



The position of the basipterygoid processes varies con- 

 siderably in different groups of birds. In all the Ratitse, 

 and, amongst the Carinatse, in the Crypturi, the basiptery- 

 goid process springs from the basisphenoid, and not from 

 its rostrum, and articulates with the pterygoid near the 

 quadrate. In most other Carinate birds, wherever it has not 

 been absorbed, it springs from the basisphenoid rostrum; 

 and in most of the Charadriidse it articulates with the ptery- 

 goid near the centre of that bone. In the Gallinse it is 

 situate still further from the quadrate — so much so, indeed, 

 that in many species the facet which articulates with the 

 pterygoid adjoins the end of the palatine. This character 

 completely breaks down in the Tubinares, and partially so in 

 tlic Gralhe, as will hereafter be pointed out when these sub- 

 orders are discussed. 



The Sternu7n. 

 Although Dr. Parker says (Trans. Zool. Soc. v. p. 227) 

 that the sternum is " the worst part for the systematist to 

 hold by," we may possibly find that it will help us where 

 other characters fail. 



