68 THE EXTINCT BATKACHIA, REPTILIA 



The lumbars grow widest as respect the centrum, to the sacrum. The two sacral vertebra? 

 are the broadest and most depressed and their cups and balls are flattened. 



The parapophyses rise from the atlas till they stand truncated above by neurapophysial 

 suture on the fifth dorsal. On the sixth dorsal they stand just above the suture, and on 

 the seventh on a level with anterior zygapophysis (H. brevispinis). Among modern Croc- 

 odiles, Caimans and Gavials, Cuvier found hypapophyses on the anterior five or six dorsal 

 vertebrae ; on the Holopes and Thoracosaurus these processes are visible on the eighth, 

 and probably on the ninth in H. brevispinis Cope. 



The teeth in this genus are much curved. They have long conic crowns with minute 

 lateral cutting edges and minute stria? of the enamel, but no proper ridges as in Hypo- 

 saurus. The teeth in T. neocaesariensis are blunter than in the others. In the H. 

 glyptodon, the teeth are coarsely fluted, and the surface everywhere, finely and sharply 

 striate. 



As the vertebrae of the species of this genus are very numerous, and the crania are 

 usually much mutilated before coming to the hands of students, I give a synopsis of their 

 characters, including those of Thoracosaurus and Bottosaurus. 



I. Cervicals with deeply bifid hypapophyses, and transversely oval cup. 

 Dorsals with transverse oval cups. 



T. NEOCAESARIENSIS. 



II. Cervicals with short united transverse hypophyses, slightly bifid posteriorly; 

 anterior extremities more or less quadrate. 



Smallest species, vertebra? 1 6 lines long (-without ball) ; cups of all transverse oval. 



H. BREVISPINIS. 



Large ; dorsals about third and fifth, with snbcordate outline and thin margins ; i. e., 

 widened above, narrowed below, wider than deep ; centra 20-25 lines ; cervicals with 

 subquadrate cup. 



H. CORDATUS. 



Large, centra 20-25 lines long ; dorsals about seventh, etc., much compressed ; cups 

 deeper than wide, third and fourth regularly round or oval, not cordate, with thick lips ; 

 cups of cervicals round or transverse oval. 



H. OBSCUEUS. 



III. Posterior cervicals with hypapophyses scarcely traceable, and well separated. 

 Large species ; dorsals near seventh, with transverse oval cup, with thick margins ; 



cups of cervicals subquadrate, bodies little keeled below ; centra 20-25 lines long. 



H. TENEBROSUS. 



