158 



KEPTILIA 



CLASS III 



anteriorly. Quadrate large, with prominent supra- 

 stapeclial process extending below the middle of the 

 bone ; opening for the auditory meatus large, not 

 entirely enclosed. Teeth slender and recurved, 

 facetted on the outer side, striate on the inner ; 

 maxillae with about twelve, and pterygoid ten to 

 twelve teeth. Coracoid deeply emarginate on inner 

 border. Four carpals and three tarsals present, 

 closely articulating. Fifth digit shorter than the 

 fourth, and divergent. Chevron bones large, loosely 

 articulated. Abundant and represented by numerous 





c 



CD 



(V 



u 

 o 



-4-< 



CO 



a; 



^ Pi 



e 



O 



o 



S 



e 



i h 



m 



'<$> 





Fig. 249. 



Plateau-pus coryphaeus, Cope. Upper Cretaceous ; Logan County, 

 Kansas. Skull, superior and lateral aspects, 1/7 (after Merriani). 



species in the Upper Cretaceous of Kansas, Colorado, 

 Texas, North Dakota, and France. 



Holosaurus, Marsh. Yery similar to the preceding, 

 except that the coracoids are not emarginate ; there 

 are no zygosphenes in the only known specimen. 

 Kansas. 



Plioplatecarpus, Dollo (Oterognathus, Dollo). Similar 

 to Platecarpus, but with smaller chevron bones. Quad- 

 rate with large meatal opening. Mandible slender, 

 coronoid rudimentary. Teeth long and slender, 

 facetted, and striate. Danian of Maestricht, and 

 Upper Senonian of Belgium. 



Prognathosaurus, Dollo. Skull about 0*6 m. long. 

 Pterygoids nearly as large as the maxillae, and with 

 very powerful teeth. The large suprastapedial process 

 of the quadrate coossifles with the infrastapedial 

 process, and encloses an oval foramen. A wide canal 



