Phacoides (Pleurolucina) leucocymoides, new species.
Tres Marias (1930). Type 11386, Lowe collection; paratypes, San Diego Society of Natural History, Carmen Island, Gulf of California, 20 fathoms (1932) and Lowe collection, Angel de la Guardia Island, Gulf of California, 20 fathoms (1932).
Shell convex, thin, white; entire surface covered with sharply reflexed concentric lirae, which are much stronger and further apart than in Phacoides undatus Cpr. Instead of three radiating costae with four narrow interstices on each valve, as in Carpenter's species, there is but a single wide costa with a channeled groove on either side. The shell is higher and narrower than P. undatus and somewhat resembles P. Icucocyma Dall (Proc. U. S. Nat. Muse., vol. 12, p. 263, pl. 14, figs. 6-7, 1889) from the Atlantic coast. The interior marginal crenations and cardinal teeth are more prominent than in P. undatus Cpr., while the subumbonal pit is not so deep as in that species.
Diameter 10.7 mm., altitude 11.1 mm.