142 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Range. Santa Barbara, California, to Todos Santos Bay, Lower 
California. In the Pliocene at Calleguas Ranch, Ventura County, and the 
Pleistocene at San Pedro and San Diego, California. 
Subgenus Cerastoderma Morch, 1853. 
Cardium corbis Martyn, 1784. 
Plate 34, figs, la, lb. 
Figs. Nondescript Shells, table 2, pi. 80. 
Shell large, subtrigonal, ventricose, thick; umbones prominent, an¬ 
terior to center; surface ornamented with about thirty-seven prominent, 
regular, squarish, close-set, radiating ridges, which are made more or less 
rugose by incremental ridges on their surface; near the posterior margin 
these ridges become more rounded and less prominent; between the ridges 
are equal, deep, canal-like grooves; margin crenulated; ligament short, 
external, prominent; each valve with one prominent cardinal tooth, and 
two laterals, one anterior and the other posterior; muscle impressions 
prominent, subequal. Length, 71; height, 71; diameter, 57 mm. (Arnold.) 
Type in the Swainson Collection. Type locality, Pulo Condore. 
Range. Nuvivak, Pribiloff, and Commander Islands to Hakodate, 
Japan, and to San Diego, California. In the Pleistocene at San Francisco, 
Monterey, San Pedro, and Santa Barbara. 
Cardium ciliatum Fabricius, 1780. 
Plate 19, figs. 8, 8a. 
Fauna Gronl., p. 410; Binney and Gould, Invert. Mass., fig. 150. 
Cardium testa subcordata, fulcis elevatis subtriquetris ciliatis. Long. 
.19 inch. (Fabricius.) 
Shell large, rather thin, a little obliquely rounded-ovate; anterior part 
shortest and narrowest, ends regularly rounded; beaks prominent, the 
points turned inward, and nearly in contact; in front of them is a narrow, 
heart-shaped depression; on each valve are 36, or more, three-sided sharp- 
edged, radiating ribs, furrows between them rounded, and regularly 
wrinkled by the lines of growth; epidermis yellowish brown, lax, and 
bristling into a stiff fringe on the sharp edge of the ribs; within straw 
colored, the portions covered by the mantle pearly; grooves, answering to 
the ribs without, are obvious within, and the edges are strongly notched. 
The above description is of C. islandicum, but is equal to C. ciliatum. 
(Gould’s Invert. Mass.) 
Type in the Copenhagen Zool. Museum. Type locality, Greenland. 
Range. Arctic Ocean to Puget Sound and Japan. Also circumboreal. 
