Plate 20. 
Page 
igure 1. Spisula falcata Gould . 195 
• Interior of left valve. 
2. Spisula falcata Gould . 195 
Hinge. 
3. Spisula falcata Gould . 195 
Exterior of left valve. 
Figures 1, 2, 3, arc figures of Gould’s types. 
4. Mactra calif arnica Conrad . 192 
Interior of right valve. 
5. Mactra californica Conrad . 192 
Exterior of left valve. 
6. Mactra calif ornica Conrad .. 192 
Interior of left valve. 
Figures 4, 5, 6 from University of California, 
Vol. 9, Packard. 
