CLASS PELECYPODA 
189 
Ensis californicus Dali, 1899. 
Proc. U. S. N. M., 22:110. 
Shell small, slender, arcuate, the sides nearly parallel, the valves being 
slightly attenuated toward the ends, beaks anterior, the anterior truncation 
bluntly rounded, the posterior similar; color white with livid pink streaks 
concentrically disposed; epidermis olivaceous brilliantly polished; hinge 
with small and very delicate cardinals (usually broken off), one in the 
right and two in the left valve, the dorsal ridge comparatively strong and 
elevated, shorter than the ligament. Length, 60 mm. (Dali.) 
Type in U. S. N. M., No. 158891. Type locality, off the Island of 
San Pedro Martir, Gulf of California. 
Range. Monterey, California, to the Gulf of California. 
Genus SILIQUA Mergerle, 1811. 
Shell smooth, oblong; epidermis polished; an umbonal rib extending 
across the interior of the valve; pallial sinus short. 
Type. Solen radiatus Linnaeus. 
Distribution. India, China, Okhotsk, Bering Sea, Sitka, Oregon, 
California, Newfoundland, Atlantic United States. 
Siliqua lucida Conrad, 1837. 
Plate 52, fig. 2. 
Jour. Acad. Nat. Sci., 7 :231; pi. 17, fig. 8. 
Shell oblong, oval, compressed, thin, fragile, translucent; posterior 
extremity nearly direct, truncated; color bluish, with purple concentric 
zones, and two oblique pale rays on the posterior side; interior rib nearly 
direct. (Conrad.) 
This was described as Solicurtis lucidus by Conrad. 
Type locality, near Santa Barbara, California. 
Range. Monterey, California, to Todos Santos Bay, Lower California. 
In the Pleistocene at San Pedro and San Diego, California. 
Siliqua media Gray, 1839. 
Zool. Beechey’s Voy., p. 153; pi. 44, fig. 2. 
Shell rather compressed, oblong-elliptical, gaping at each end, covered 
with a thick, greenish, shining epidermis; fortified within by a strong rib 
under the umbo in each valve; anterior side short, semi-ovate; posterior 
side oblong, dorsal margin rather straight; terminal margin rather trun¬ 
cated, ventral margin convex, sloped upward at the end. (Conch. Iconica.) 
Type in British Museum. Type locality, Bering Sea? 
Range. Arctic Ocean and south to the Okhotsk Sea, Bering Sea, and 
Cook Inlet, Alaska. 
