236 



EEPTILIA 



CLASS III 



quadrant of arc, so that the pubic symphysis 

 is formed by the lateral faces instead of 

 extremities of the bones. Upper Jura; 

 Wyoming and Colorado. 



Apatosaurus, Marsh. Upper Jura; 

 Colorado. Pleurocoelus, Marsh. Lower Cre- 

 taceous ; Maryland. 



Ornithopsis, Seeley (Pelorosaurus, Mantell ; 

 Eucamerotus, Hulke ; Chondrosteosanrus, Both- 

 riospondylus, Owen), (Fig. 334). Cervical 



Pig. 339. 



Diplodocw longus, Marsh. Upper Jura ; Canon City, Colorado. 

 Skull, i/s (after Marsh). 



vertebrae elongated, dorsals with expanded 

 neural canal. Fragmentary remains of large 

 size frequent in the Upper Jura and Wealden 

 of England. 0. hulkei, Seeley. 



Titanosaurus, Argyrosaurus, Lydekker. 

 Supposed Cretaceous of Patagonia. 



Family 2. Diplodocidae. Marsh. 



Teeth slender and cylindrical, confined to 

 front margin of the jaws. External narial 

 opeiiimj small, unpaired, placed at apex of the 

 skull. Caudal vertebrae elongated, ventrally 

 excavated ; chevron bones double posteriorly, each 

 having both anterior and posterior branches. 

 Upper Jura. 



Diplodocus, Marsh (Fig. 339). Total 



1; 

 "3 





— " 



a 



3 





=5 



8 



o 



