174 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL, 37. 
CREPIDULA DILATATA Lamarck. 
Crepidula dilatata Lamarck, Anim. s. Vert., vol. 6, 1822, pt. 2, p. 25.—BRropERIP, 
Trans. Zool. Soc. London, vol. 1, 1834, p. 2038, pl. 28, fig. 11. 
On oysters and other objects in about 5 fathoms, near Matacaballa, Sechura Bay; 
also on the beaches. Also from rocks at the north end of Callao water front, and on 
the north shore of San Lorenzo Island; called by the fishermen ‘‘ piques.’’ Found 
breeding in February. 
Distribution.—From the Straits of Magellan northward to Mazatlan, 
Mexico, and at the Galapagos Islands. 
Shell slipper shaped, rounded, brownish with a white septum inter- 
nally; upper surface convex, varying from nearly smooth to lamellose, 
the general form irregular, conforming to the individual situs. 
Length about 30 mm. 
CREPIDULA CREPIDULA Linneus. 
Patella crepidula Lrinnus, Mus. Lud. Ulric, 1764, p. 689.—FAaVANNE, Conch., 
pl. 4, fig. D 
Crepidula unguiformis Lamarck, Anim. s. Vert., vol. 6, 1822, pt. 2, p. 25.— 
GuALTERI, Test., pl. 69, fig. H. 
In dead shells on the flats at Capon. 
DMstribution.—The whole Peruvian province, in dead shells, and 
northward to the Gulf of California. 
Shell oval, flattened or dorsally concave, white, corresponding to 
the curve of the shell in which it is found; of irregular outline, con- 
forming to its situs; length about 35 mm. It has no economic value. 
CREPIDULA ONYX Sowerby. 
Plate 23, figs. 2, 5 
Crepidula onyx SowERBY, Gen. Shells, fascic. 23, 1824, Crepidula, fig. 2 
In various parts of Sechura Bay, adhering to oyster shells and other objects; and 
dredged off Matacaballa in about 5 fathoms. 
Distribution.—From San Pedro, California, southward to Chile. 
Shell shpper shaped, oval, with a smooth convex upper surface, a 
short, hardly prominent apex, and the internal septum white, with a 
nearly straight margin, and covering nearly half of the cavity of the 
shell; the exterior is more or less painted with brown spots, streaks 
or markings on a lighter ground; the interior usually dark brown, the 
septum white. It reaches a length of 45 mm. 
The flesh of the analogous C. fornicata Lamarck, of the Atlantic 
coast of North America is regarded as a dainty in the raw state by 
epicures, but there is no information as to the economic use of the 
present species. The other species of the genus found in Peru are too 
small to be of much importance. 
