510 CALIFORNIA ACADEMY OF SCIENCES [Froc. 4th Ser. 



Plate IX. 



Fig. 1. Ischnochiton acrior Carpenter. Exterior view of head valve 

 from Deadman Island, San Pedro, California (probably Pleistocene) 

 [685]. 



Fig. 2. Ischnochiton acrior Carpenter. Interior view of same valve; 

 same scale as preceding. 



Fig. 3. Ischnochiton acrior Carpenter. Profile of same valve; camera 

 outline. 



Fig. 4. Ischnochiton acrior Carpenter. Exterior view of median valve 

 from "coal mine", west side of Point Loma, California (Upper San Pedro 

 Pleistocene) [343]. 



Fig. 5. Ischnochiton acrior Carpenter. Interior view of same valve; 

 same scale as preceding. 



Fig. 6. Ischnochiton acrior Carpenter. Anterior elevation of same 

 valve ; camera outline. 



Fig. 7. Ischnochiton acrior Carpenter. Exterior view of fragmentary 

 tail valve from Long Wharf Canyon, Santa Monica, California (Upper 

 San Pedro Pleistocene) [352] ; same scale as Fig. 1. 



Fig. 8. Ischnochiton acrior Carpenter. Interior view of same valve; 

 same scale as preceding. 



Fig. 9. Ischnochiton acrior Carpenter. Profile of same valve; camera 

 outline. 



