430 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



EXPLANATION OF PLATE XLIX. 



Upper Trias, Noric stage, Pseudomoiiotis beds, Robinson's (Gifford's) 

 Ranch, Plumas County, California. 



Page 

 Figs. 1-3. Pseudomonotis subcircularis Gabb 4°? 



Fig. I showing adult left valve ; fig. 2 showing adult right valve, with 

 the byssal ear; fig. 3, young right valve, with byssal ear. 



