238 



Un iversit y of Ca Ufornia . 



[Vol. 3. 



"The Rattlesnake gravels contain many vertebrate remains, 

 most of which have hitherto been listed with the Mascall fauna. 

 The Rattlesnake fossils, when weathered out, are frequently to 

 be found resting - upon the Mascall beds below, and as most of 

 the material from both Rattlesnake and Mascall is found detached 

 from the matrix, the difficulties in the way of separating the 

 faunas are considerable." 



The bones sent me are hard and thoroughly fossilized, and 

 the color and the character of the fossilization appears to be 

 identical in the two cases. For reasons given below I regard 

 provisionally the questionable materials as having been derived 

 from the Rattlesnake beds. 



According to Dr. Merriam's report, the the Mascall beds 

 belong to the upper Miocene, the Rattlesnake deposits to the 

 Pliocene. 



I take as the type of this species the bone bearing the number 

 2219 of the Palseontological Department of the University of 

 California. This is the left hyoplastron, having the outer 

 _ posterior portion, which enters into 



of the genus Clemmys, represented to-day on the Pacific Coast 

 by Clemmys marmorata. The free border of the bone between 

 the humeral buttress and the epi-hyo-plastral suture is acute. 



CLEMMYS HESPERIA sp. HOV. 



the bridge, missing. Figure 1 repre- 

 sents it the natural size and as viewed 

 from below. The sutural edges are 

 present which met the hyoplastron of 

 the opposite side, the postero-lateral 

 border of the entoplastron, the hinder 

 extremity of the epiplastron, and the 

 front of the hypoplastron. As will 



Figure 1. 



j be observed, the humero - pectoral 

 sulcus, represented by a dotted band, 

 crosses the entoplastron, while the 

 pectoro-abdominal sulcus is well back 

 on the hyoplastron. The structure 

 of these parts is identical with that 



