PLATE 29 
All figures approximately natural size 
Fig. la. Mya arenaria Linnaeus. Longitude 84 mm. Fish 
Market, San Francisco. Exterior of left valve. 
Fig. 1b. Mya arenaria Linnaeus. Interior of left valve. 
Fig. 2a. Mya (Platydon) cancellata (Conrad). Longitude 55.4 
mm. Bolinas. Exterior of both valves. 
Fig. 2b. Mya (Platydon) cancellata (Conrad). Interior of both 
valves. 
[390] 
