50 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
rounded. Externally the shell is clothed with a rather spongy epidermis; 
with somewhat distant rows of bristles which form an elegant comblike 
fringe at the edges. Inside the solid ligament is stretched along the 
dorsal edge; the mantle marking runs down from it to an even distance 
from the edge of the shell. The scar of the adductor muscle is near the 
center and not conspicuous. The posterior end is gaping; the front is 
wavy on account of the slender byssus. (A free translation.) Length, 13; 
width, 2; height, 2 mm. 
Type in U. S'. N. M. Type locality, Cape San Lucas, Lower Cali¬ 
fornia. 
Range. Forrester Island, Alaska, to the Gulf of California. 
Family OSTREID^. 
Genus OSTREA Linnaeus, 1758. 
Shell irregular, attached by the valve; upper valve flat or concave, 
often plaited or foliaceous, and with a prominent beak; ligamental cavity 
triangular or elongated; hinge toothless; structure subnacreous, laminated, 
with prismatic-cellular substance between the margins of the laminae. 
(Tryon. S. S. Conch.) 
Type. Ostrea cdnlis Linn. 
Distribution. Tropical and temperate seas. 
Range in time. Carboniferous to Pleistocene. 
Ostrea lurida Carpenter, 1864. 
Plate 37, figs. 10a, 10b. 
Suppl. Rep. Brit. Assoc., p. 646; Jour, de Conchol, 12:138. 
O. t. irregulari, suborbiculari, ellipsoidea, seu producta; superficie 
interdum laminata, purpurea seu squalide grisea, haud, costata: 
intus olivacea, interdum purpureo tincta, seu omnino purpurea, sub- 
margaritacea; cardine recto; umbonibus haud conspicuis, haud excavatis; 
margine interno, cardinem versus ssepe crenulato. (Carpenter.) 
Type in U. S. N. M. Type locality, Vancouver Island. 
Range. Sitka, Alaska, to Cape San Lucas, Lower California. In the 
Pleistocene at Benicia, Solano County, and San Pedro and San Diego, 
California. 
Ostrea lurida expansa Carpenter, 1864. 
Suppl. Rep. Brit. Assoc., p. 646; Jour, de Conchol., 12:138. 
T. omnino planata, per totum superficiem afifixa; extus, marginem 
versus laminata, purpureo radiata; intus, olivaceo-rufa, ligamento parvo, 
in medio undato, solidiore. (Carpenter.) 
Type in U. S. N. M. Type locality, San Pedro, California. 
Range. Monterey to San Diego, California. 
