504 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



Plate VI. 



Fig. 1. Katharina tunicata (Wood). Exterior view of head valve from 

 Deadman Island, San Pedro, California (Pleistocene) [345]; tegmentum 

 lost from this specimen. 



Fig. 2. Katharina tunicata (Wood). Interior view of same valve; same 

 scale as preceding. 



Fig. 3. Katharina tunica/a (Wood). Profile of same valve; camera 

 outline. 



Fig. 4. Katharina tunicata (Wood). Exterior of median valve from 

 Deadman Island, San Pedro, California (Santa Barhara Pliocene) [726]. 



Fig. 5. Katharina tunicata (Wood). Interior of same valve; same scale 

 as preceding. 



Fig. 6. Katharina tunicata (Wood). Anterior elevation of same valve; 

 camera outline. 



Fig. 7. Mopalia cf. sinuata (Carpenter). Lateral view of head valve 

 from Deadman Island, San Pedro, California (probably Pleistocene) [717]. 



Fig. 8. Mopalia cf. sinuata (Carpenter). Sculptural detail of same 

 specimen, greatly magnified. 



Fig. 9. Acanthochitona avicula (Carpenter). Exterior of imperfect 

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

 San Pedro Pleistocene) [940]. 



Fig. 10. Cryptochiton stcllcri (Middendorff ). Interior view of head 

 valve from C. A. S. Loc. 108, 2 miles north of Point Loma, California 

 (Upper San Pedro Pleistocene) [517]; showing radial lines made visible 

 by delamination of inner layer of articulamentum. 



Fig. 11. Cryptochiton stelleri (Middendorff). Exterior of median valve 

 from Pacific Beach, San Diego County, California (San Diego Pliocene) 

 [505] ; camera outline. 



Fig. 12. Cryptochiton stcllcri (Middendorff). Exterior view of tail 

 valve from Nob Hill Cut, San Pedro, California (Lower San Pedro 

 Pleistocene) [644] ; camera outline. 



