CLASS PELECYPODA 
161 
and no escutcheon; inner margins not crenate; pallial sinus distinct, 
angular; hinge with three delicate entire cardinals in each valve, but no 
laterals. (Dali.) 
Type. Chione lordi Baird, 1863. 
Distribution. Pacific coast of North America from Bering Sea to 
Lower California. 
Range in Time. Pleistocene, Pliocene. 
Psephidia lordi Baird, 1863. 
Plate 6, fig. 3. 
Proc. Zool. Soc., p. 69; pi. 2, fig. 10. 
Shell small, of an ovate-triangular shape, a smooth shining appearance, 
and a light olive color. The surface is concentrically marked with slight 
grooves. The beaks are prominent and very shining. Internally the sur¬ 
face is white, the margins of the shell very finely crenulate, and the pallial 
impression short and blunt. (Baird.) 
Type in Brit. Mus. Type locality, Esquimalt Harbor, Vancouver 
Island, British Columbia. 
Range. Unalaska, Alaska, to Coronado Islands, Lower California. 
Psephidia ovalis Dali, 1902. 
Plate 34, fig. 4. 
Proc. U. S. N. M., 26:407; pi. 16, fig. 4. 
Shell small, white, polished, oval, subcompressed; surface with obsolete 
concentric threads near the anterior base, but over most of the disk 
smooth; beaks small and very low, at about the anterior third of the 
length; lunule elongated, extremely narrow, nearly as long as the anterior 
dorsal slope; escutcheon linear or none; interior white, the pallial sinus 
moderate, pointed; internal margin delicately striated; hinge well devel¬ 
oped, like that of P. lordi f with three entire cardinals and no anterior 
lateral tooth. Length 8.5 ; height, 6.5 ; diameter, 3 mm. (Dali.) 
Type in U. S. N. M. Type locality, north side of Catalina Island, 
California. 
Range. St. Paul Island, Bering Sea, to San Diego, California. 
Psephidia cymata Dali, 1913. 
Plate 22, fig. 3. 
Proc. U. S. N. M., 45:593. 
Shell small, white, solid, rounded triangular, with inconspicuous, some¬ 
what anterior beaks, the lunule and escutcheon very feebly indicated; 
surface with fine concentric but not perfectly regular low threadlike sculp- 
