CLASS PELECYPODA 
139 
far as can be ascertained, is simple and not sinuated. The cardinal edge 
is very narrow, only jutting out just at the shorter side, to which portion 
of it the dentation is confined. The extreme minuteness of the teeth 
almost baffles one’s eyesight, even when aided by the most powerful lens. 
Length, y 12 of an inch; breadth, a trifle more than half that. (British 
Mollusca.) 
Type locality, Greenland. 
Range. Bering Strait to Magdalena Bay, Lower California. Also 
North Atlantic. 
Turtonia occidentalis Dali, 1871. 
Amer. Jour. Conch., 7:150; pi. 14, figs. 12, 13. 
Shell subtrigonal, slightly inequilateral, small and smooth. Color 
purplish; lighter, with a yellowish epidermis, toward the margin, especially 
anteriorly; interior dark purple in the middle of the valves, margins lighter, 
dark brown above and behind. Hinge line and ventral margin roundly 
arcuate, ends rounded, anterior a little shorter and smaller. Epidermis 
yellowish brown, polished, with rather strong lines of growth at intervals. 
Umbones rather prominent, usually eroded. Shell a little tumid. Teeth 
strong, apparently three cardinals in the left valve, with the posterior 
dorsal hinge margin folded in making a strong tooth-like lamella. Right 
valve with one long and one triangular cardinal tooth, and a posterior 
lamella as in the other. Pallial line simple, slightly waved near the pos¬ 
terior muscular scar. Anterior scars two, perfectly separate and distinct, 
the upper triangular, slightly smaller. Length, .2; height, .16; diameter, 
.1 inch. (Dali.) 
Type in U. S. N. M. Type locality, Plover Bay, Eastern Siberia. 
Range. Known only from the type locality. 
Genus SPORTELLA Deshayes, 1858. 
Shell oblong, smooth, depressed, subequilateral; valves closed. Hinge 
narrow, with two unequal, diverging teeth in the left valve, one in the 
other; the lateral teeth are wanting. Muscular scars large, oval, nearly 
equal; pallial line simple. Ligament external. (Tryon. S. S. Conch.) 
Type. Psammotea dubia Deshayes. 
Distribution. Living on the coast of California. 
Range in time. Tertiary of Europe and Eastern United States. 
Sportella californica Dali, 1899. 
Proc. U. S. N. M., 21:885; pi. 88, fig. 5. 
Shell small, compressed, rude, with a yellowish epidermis; slightly 
arcuate, dorsal margin evenly arched, base concavely arcuate; inequilateral, 
