PLATE IX. 



PAGE 



Fig. 53. Arca sulcicosta. Natural size. 31 



53 a. Magnified view of the surface. 

 Pig. 54. Yoldia Cooperi. Natural size. 31 



From the recent specimen found by Dr. Cooper near Santa Cruz. 

 Fig. 55. Pecten Cerrosensis. 32 



One-half natural size. 

 55 a. End view to show convexity of the valves. 



