UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 4, No. 2, pp. 33-38, PI. 5 ANDREW C. LAWSON, Editor 



A PRIMITIVE ICHTHYOSAURIAN LIMB 



FROM THE 



MIDDLE TRIASSIC OF NEVADA. 



BY 



John C. Mebriam. 



During' the last summer an expedition from the University 

 of California spent some weeks in searching for iehthyosaurian 

 remains in the Middle Triassie limestones of Nevada. Both Mr. 

 E. L. Furlong, who directed the work, and Mr. H. M. Evans, who 

 accompanied him, discovered unexpectedly good material, which 

 will make possible considerable advances in our knowledge of 

 these very early forms. 



The oldest known Ichthyosaurians of which more than iso- 

 lated elements or very fragmentary material have been described 

 are the Mixosaurs of the North Italian Triassie. They were 

 obtained from beds which have been held to represent the upper 

 portion of the Middle Triassie. The oldest American Ichthyo- 

 saurs of which more than the vertebrae have been described are 

 the Shastasaurs and the accompanying types from the Upper 

 Triassie of California. Up to this time the limbs and arches of 

 the North American Middle Triassie forms have been known only 

 from scattered bones, the description of which has been withheld 

 until more satisfactory material should be obtained. 



Among the specimens discovered this year is one which shows 

 the anterior half of the vertebral column, one side of the pec- 

 toral arch complete, the first two segments of a pectoral limb, 

 and nearly the entire skull. It was found in the Middle Triassie 

 limestones of Cottonwood Canon by Mr. H. M. Evans. As 



