PLATE 30 
Fig. la. Pholadidea ovoidea (Gould). X 1. Longitude 37 mm. 
Bolinas. Exterior of left valve showing siphons extended. 
Fig. 1b. Pholadidea ovoidea (Gould). X 1. Dorsal view, show- 
ing siphons extended. 
Fig. 2a. Pholadidea ovoidea (Gould). X 1. Longitude 19 mm. 
Ventral view of an immature specimen. 
Fig. 2b. Pholadidea ovoidea (Gould). X 1. View of left valve 
of same specimen. 
Fig. 3a. Pholadidea penita (Conrad). XX 1. Longitude 50 mm. 
Bolinas. Exterior of left valve, showing siphons extended. 
Fig. 3b. Pholadidea penita (Conrad). X 1. Dorsal view. 
Fig. 4. Saxicava arctica (Linnaeus). X 2. Longitude 13 mm. 
Station 5700.* Exterior of left valve. 
Fig. 5. Saxicava pholadis Linnaeus. X 1. Longitude 34.6 mm. 
Goat Island, San Francisco Bay, Exterior of left valve. 
