CLASS PELECYPODA 
127 
the typical annulatiis. Length, 54; height, 50; diameter, 25 mm. (Dali.) 
Type in U. S. N. M., No. 108819. Type locality, Harbor of Sitka, 
Alaska, Station 92. 
Range. Sitka, Alaska, to Esteros Bay, California. 
Phacoides aequizonatus Stearns, 1890. 
Proc. U. S. N. M., 13:220; pi. 17, figs. 3, 4. 
Shell moderately convex, dull white chalky where eroded; epidermis 
of a dull dingy light yellowish tinge, finely wrinkled in old specimens, and 
inclined to be deciduous and slightly flaky or ragged; in young shells, 
translucent, shiny, and nearly colorless. Valves transversely ovate, being 
broader than high; the posterior side is abruptly squarish, and the dorsal 
line slants gradually from the umbones; on the anterior side the dorsal 
outline is moderately concavely curved away from the beaks, and in the 
young and perfect specimens a very slight angulated pinch may be seen 
extending from the lunule to the anterior edge of the valve. The beaks 
or umbones are small, inclined toward the lunule; the lunule is quite 
narrow, attenuated lanceolate and elongated. Surface of valves trans- 
versed with fine concentric growth lines, and prominent rather regularly 
spaced thread-like ridges. Hinge line curved and showing two diverging 
cardinal teeth in each valve; the anterior one in the left valve, and the 
posterior one in the right valve, notched or partially cloven. Elongated, 
tuberculoid lateral teeth in both valves at extreme limit of dorsal line. 
From beaks to ventral margin, 37.50; from anterior to posterior edges of 
valves, 46.25 mm. (Stearns.) 
Type in U. S. N. M., No. 104044. Type locality, off Santa Barbara 
Islands, California, in 276 fathoms. 
Range. Santa Barbara Islands, California, to South Latitude 38 
(Chile). 
Subgenus Callucina Dali, 1901. 
SECTION EPILUCINA Dali, 1901. 
Phacoides californicus Conrad, 1837. 
Jour. Acad. Nat. SciPhila., 7:255; pi. 20, fig. 1. 
Shell lenticular, with coarse concentric striae; posterior extremity 
direct; lunule small, elliptical, impressed, transversely striated, prominent 
in the right valve, and fitting into a corresponding depression in the left; 
cardinal and lateral teeth prominent. (Conrad.) 
Type in U. S. N. M. or State Museum, Albany, New York. 
Range. Crescent City, California, to San Ignacio Lagoon, Lower 
California. In the Pleistocene at Santa Barbara, San Pedro and San 
Diego, California. 
