104 



University of California. 



LVOL. 3 



FORMS FROM MIDDLE TRIASSIC OF NEVADA, 

 CYMBOSPONDYLUS GROUP. 



CYMBOSPONDYLUS LEIDY. 

 Proe. Philad. Acad. Sci. 1868 v. 20 p. 177. 



This genus was founded by Leidy upon several fragmentary 

 and imperfectly prepared vertebrae "from the Triassic rocks of 

 Star Canon, Humboldt Co. (Nevada), and from the Toiyabe 

 Range, northeast of Austin, Nevada." With the type specimen 

 from New Pass, in the Toiyabe Range, are "two shells which 

 appear to be Ammonites blakei Gabb and Posidonomya stella 

 Gabb." 



According to Professor James PeiTin Smith the presence of 

 Am. blakei indicates that these beds are middle Triassic and con- 

 sequently older than those from which the saurians were obtained 

 in Northern California. These remains, therefore, represent the 

 oldest known Ichthyopterygians of this coast, and among the oldest 

 that have ever been discovered. Two species were described by 

 Leidy, C. piscosus and pet rin us. C. piscosus is the first mentioned 

 and must be taken as the type of the genus. Following are the 

 principal parts of Leidy 's description of the type specimen, 

 which consists of portions of five vertebra?. 



Cymbospondylus piscosus Leidy. 

 Pl. 16, pigs. 1 and 2. 



"The body of the vertebra? is deeply biconcave, as in Ich- 

 thyosaurus. The length is considerably less than the breadth. 

 The under side is plane fore and aft, but the margins are slightly 

 prominent and bevelled. The sides are slightly concave and 

 provided with a short and robust process for the head of a rib. 

 The neural arch, with its spine visible in one vertebra along the 

 broken margin of the specimen, rises above the body about one 

 and one-half times its depth, and its abutment exhibits the 

 remains of another articular process for the rib. The neural 

 canal is triangular." 



From New Pass, in the Toiyabe Range, northeast of Austin, 

 Nevada. 



From this diagnosis the writer found it impossible to deter- 



