88 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
but not felt. They correspond to the points of attachment of the mantle. 
The flat valve has the ventral margin rather evenly curved, with no sinus. 
The dorsal margin is bent over at a right angle behind the hinge, and 
angulated at the umbo. The surface is marked by an area corresponding 
to that on the convex valve, and with a similar concentric striation, but 
not separated from the rest by an incised or any other definite line. Behind 
the area thus marked the flat valve is a little concave, marked by faint, 
concentric waves and radiating, irregular lines, marked on the shell by a 
light groove, but carrying a raphe of epidermis. Interior pearly, with 
the anterior tooth very strong. Length, 2.2; depth, hinge to ventral margin 
of convex valve before the sinus, 1.5; behind the sinus, 1.04; diameter, 
0.38 inches. (Dali.) 
1 ype in U. S. N. M., No. 171069. Type locality, Unalaska. 
Range. Pribiloff Islands, Bering Sea, to Sileta Bay, Oregon. 
Pandora filosa Carpenter, 1864. 
Plate 33, figs. 2a, 2b. 
Proc. Zool. Soc., p. 602, 1864, Arnold, Pal. San Pedro; pi. 18, fig. 3. 
P. t. tenui, plano-convexa, maxime rostrata; marginibus dorsalibus 
rectis, ad angulum circ. 160; ventrali regulariter et modice excurvato, 
postice vix sinuato; epidermide olivacea, plerumque erosa, postice corru- 
gata; lamina externa prismatica spongiosa; valva planata radiatim sulcata 
(quasi filosa), sulcis distantibus; valva convexa, costa obtusissima postice 
decurrente; lineis seu undis increment! conspicuis: intus dente cardinali 
uno, parvo, extante; callositate claviculoidea antica, margini contigua; 
fossa cartilaginea postice sita; cicatricibus adductorum rotundatis, margini 
dorsali contiguis; linea pallii simplici. Long., 8; lat., 4; alt., 12 poll. 
(Carpenter.) 
Shell small plano-convex, elongate-oval, thin, umbos minute, about 
one-fourth length from anterior extremity; anterior and posterior dorsal 
margin straight, making an angle of 160 degrees at the umbo; ventral 
margin arcuate; posterior extremity long, narrowed and truncated at the 
end; anterior rounded up from the base but making an angle with the 
dorsal margin; a single prominent posterior, submarginal ridge runs from 
umbo to the extremity of each valve, being nearer the margin in flat valve; 
surface of both valves sculptured by numerous fine, concentric, incre¬ 
mental lines, and that of the right valve by fine radiating sulcations; left 
valve with a thin ossicle; right valve with two ossicles, the anterior one 
being short. (Arnold.) 
Type in British Museum? Type locality, Puget Sound. 
Range. Nunivak Island, Bering Sea, to San Pedro, California. 
