64 



University of California. 



[Vol. 3 



(Merriam, 1895). The genus was stated to have its closest 

 affinities with the.Ichthyosauria but to differ in some important 

 particulars from all known forms in that group. 



During the summer of 1901, the writer visited the Triassic 

 areas of Shasta County in company with Professor Smith and a 

 party of students from Stanford and California universities. On 

 this expedition a considerable quantity of new material was 

 obtained. In the fall of 1901, Miss A. M. Alexander generously 

 contributed funds for another expedition into the Shasta region.' 

 Under the direction of Mr. H. W. Furlong, this party spent two 

 months in the field and obtained some very valuable specimens. 



In working up these collections, it was found necessary to com- 

 pare the Californian material with that which had been described 

 from the Triassic of Nevada by Dr. Joseph Leidy, and through 

 the kindness of Dr. Charles R. Eastman the type specimens of 

 Leidy' s species were obtained for study from the Whitney collec- 

 tion at Harvard University. In examining them it was discovered 

 that Leidy had overlooked the most important characters of the 

 species which they represent. The writer has, therefore, included 

 in this paper a redescription of the known Nevada forms. 



Practically all of the saurian material that is known to have 

 been collected in the Triassic of this coast has been brought 

 together in preparing the following discussion. Forms which 

 are not recognized as representatives of the Ichthyopterygia are 

 reserved for description in a later paper. 



For the present, two groups of species are recognized, those 

 generically identical with Shastasaurus , from the upper Triassic of 

 Northern California; and the middle Triassic forms from Nevada, 

 which are all included in Oymiospondylus Leidy. These genera 

 are probably closely related and form a well defined subdivision 

 of the Ichthyopterygia. As yet but little is known concerning 

 the structure of Cymbospondylus , while Shastasaurus is repre- 

 sented by specimens showing nearly all of the skeleton, so that 

 the principal discussion of the structure and affinities of this 

 group naturally falls in the description of the better known genus. 



For the preparation of the drawings used in illustrating this 

 paper, the writer is much indebted to Mr. Raymond Carter 

 The photographs were all taken by Mr. B. F. White. 



