CATALOGUE 



OF 



FOSSIL REPTILIA 



AMPHIBIA. 



Class REPTILIA. 



ARCHOSAURIAN BRANCH. 



The three Orders included in this branch present the following 

 characters in common. 



Teeth usually set in distinct sockets, never anchylosed to the 

 jaws, and confined to premaxilla, maxilla, and dentary. No parietal 

 foramen ; two temporal arcades ; infratemporal fossa not roofed 

 over by bone ; quadrate immovably fixed ; frequently no columella 

 (epipterygoid). Anterior ribs double-headed ! ; dorsal vertebrae 

 with long transverse processes, which may be placed entirely on the 

 arch ; frequently more than two sacral vertebrae. No T-shaped 

 interclavicle or precoracoid. Pectoral and pelvic limbs present; 

 humerus without distal foramen, but occasionally with ectepi- 



1 Zittel ('Paheontographica,' vol. xxix. pp. 03, 64) suggests that all the ribs 

 of Pterouactylus are single-headed ; and Marsh thinks that the same Btructure 

 may obtain in Coekcrus. 



B 



