244 MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
strong. Anterior declivity of the shell concave, sides flattened, posterior 
declivity rounded convex. Color whitish, with numerous radiating rays of 
brown or slate color, usually with a broad fasciculus of darker rays in 
the middle of each side extending from the apex to the margin, and 
occasional dark dots on the ribs. Shell occasionally entirely brown or slate 
color, with two darker rays on the sides. Epidermis none. Interior pure 
white, the two dark rays sometimes showing through the shell. Extreme 
outer edge finely denticulate or rounded and smooth according to the stage 
of growth. Margin as a whole broad, smooth, differentiated from the rest 
of the surface by a wide, shallow groove. Margin of the aperture simi¬ 
larly bordered. Muscular impressions distinct, surface marked by fine 
radiating lines; polished. Anterior and posterior margins internally con¬ 
cave or emarginated, so that when laid upon a flat surface in the natural 
position the ends of the shell do not touch it. Adult, long., .7;,lat., .5; 
alt., .2 in. Long, of aperture, .23; lat. of do., 12 in. (Dali.) 
Type in United States National Museum. Type locality, Monterey, 
California. 
Range. Forrester Island, Alaska, to Cape San Lucas. Fossil: Pleisto¬ 
cene, Santa Barbara, San Pedro. 
Described as Fissurellidaea bimaculata Dali. 
Genus LUCAPINELLA Pilsbry, 1890 
Fissurellidae with an oblong shell, not sunken in or covered by the 
mantle, and about as long as the foot; its apex subcentral, wholly removed 
by a rather large oblong perforation, which is margined within by an entire 
(not truncated) callus; edge of shell blunt, scarcely crenulated in adults 
except in front and behind; sculptured with scaly riblets; front and side- 
margins level, posterior margin a little elevated. Animal with a fleshy 
foot, much too large to be contained in the.shell; mantle-edge thickened, 
papillose on its lower edge and having narrow processes extending up 
over the shell-edge. (Pilsbry.) 
Type. Clypidella callomargimta Carpenter, MS. 
Distribution West coast of North and South America, West Indies, 
Barbadoes, Florida Keys. 
Lucapinella callomarginata (Carpenter, MS) Dali, 1871 
Plate 85, fig. 16 
American Journal of Conchology, 7:133; PI. 15, fig. 8. Tryon and Pilsbry, Manual 
of Conchology, 12:196; PI. 44, figs. 3, 4, 5; PI. 61, figs. 1-5. 
Shell oblong, a trifle narrower in front, rather depressed, the subcen¬ 
tral summit occupied by a rather large fissure, shaped like the shell and 
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