296 



TEETIAET VEETEBEATA OF THE FATtrM. 



In this species, which is the type of the genus, the shell is more depressed, wider 

 and more uniformly oval than in S. lihyca from the beds above. It also differs in 

 possessing a comparatively narrow nuchal bone, probably narrower than the anterior 

 vertebral shield ; in the later form the reverse is the case. From ^S*. podocnemioides, 

 Eeinach, of the same horizon, this species is distinguished by the fact that the humeral 

 shields are widely separated posteriorly by the intergular instead of terminating at the 

 same point. 



Form. & Log. — Qasr-el-Sagha beds (Middle Eocene) : north of Birket-cl-Qurun. 



Text-fig. 95. 



/SOC. 



^fimx. 



Palatal view of skull of Stereogenys cromeri, restored. 



hoc, basioccipital ; ec.pt., ectopterygoid wing ; f.i.c, fossa into which the internal carotid opens ; f.m., foramen 

 magnum; i.n., internal nares ; moc., maxilla; p./., palatine foramen; pa., parietal'; pi., palatine; 

 pma:., premaxilla ; pt., pterygoid ; q., quadrate ; soc, supraoccipital ; sq., squamosal. About | nat. size. 



The skull (PI. XXV. figs. 1-3 ; text-fig. 95) in its general structure is closely similar 

 to that of Podocnemis, but is broader and more depressed. The supraoccipital (soc.) is 

 produced backwards into a large median process, the upper surface of which appears on 

 the roof of the skull between the hinder ends of the parietals (pa.). These bones are 

 very large, forming the greater part of the skull-roof; laterally they join the quadrato- 

 jugals and jugals in a straight suture, forming with those bones a complete covering 

 for the temporal fossse, as in Podocnemis. The frontals (/.) are comparatively small, 

 and extend forwards to about the middle point of the orbits, where they join the 



