MERRTAM: TRIASSIC ICHTTIYOSAURIA. 153 



Several of the Triassic ichthyosaurian forms which are represented by frag- 

 mentary material seem to stand nearer to Ichthyosaurus than to any of the 

 typical Triassic genera, and may be referred tentatively to that genus. It is 

 not improbable that some of these when represented by better material may 

 be shown to be generically distinct from Ichthyosaurus. On the other hand it 

 is to be presumed that Ichthyosaurus was in existence in late Triassic time, and 

 there appears to be no reason why it should not be represented in the forma- 

 tions of that period in Europe where it was so abundant in the early Jurassic. 



ICHTHYOSAURUS CARINATUS Sauvage. 

 Ichthyosaurus carinatus Sauvage, Ann. Sc. Geol., t. 7, art. 6, 1876. 



Prom the Rhaetic of the vicinity of Autun, France. 



According to Sauvage this species is large, and is characterized by the flat- 

 tening of the centrum and the carina of the inferior face of the centrum in the 

 middle dorsal region. The anterior dorsal centra are oval ; the articular faces 

 are deeply concave; the diapophyses and parapophyses are widely separated. 



MEASUREMENTS OP AN ANTERIOR DORSAL CENTRUM. 



Anteroposterior diameter of centrum 60 mm. 



Height of centrum 160 



Width of centrum 145 



Length, 100 ; height, 26C ; width, 242. 



MEASUREMENTS OP A MIDDLE DORSAL CENTRUM. 



Anteroposterior diameter of centrum 57 mm. 



Height of centrum 168 



Width of centrum 173 



Length, 100 ; height, 295 ; width, 303. 



The specimens figured by Sauvage (1883, pi. 8) seem to represent a form 

 which is generically closely allied if not identical with Ichthyosaurus. 



ICHTHYOSAURUS (?) RHETICUS Sauvagp. 



Ichthyosaurus rheticus Sauvage, Ann. Sc. Geol., t. 7, art. 6. 



Kachitrema pellati Sauvage, Ann. Sc. Geol., t. 14, art. 3, p. 5; and Bull. Soc. D'Hist. 

 Nat. D 'Autun, t. 16, p. 315. 



From the Rhaetic of the vicinity of Autun, France. 



This is a large species in which the centra of the dorsal vertebra are much 

 higher than long (anteroposterior diameter or length, 100; height, 234; width, 

 243). The centra are strongly biconcave, the concavity commencing at the 



