CLASS GASTROPODA 
303 
spinules on the upper or posterior margin only. Ctenidia extending to 
valve iii. Color of outer surface of shell deep olive buff, shading to 
vinaceous fawn near the girdle and clouded with citrine drab along the 
ridge; sutural margin of head valve, all the tail valve, and vicinity of a 
sharply marked “jugal triangle” on valve iii, finely mottled dark olive. 
Girdle darker, with conspicuous whitish spots around the setae. Maximum 
length of type, 13.2 mm.; maximum width, 6.1 mm.; altitude, 2.8 mm.; 
length of shell only, 13.0 mm.; width of tegmentum of valve iv, 5.1 mm., 
of valve v, 5.2 mm. (Berry.) 
Type in Berry Collection, No. 4908. Type locality, tide pool in the 
“Devil’s Slide,” La Jolla, California. 
Range. Known only from the type locality. 
Mopalia muscosa Gould, 1846 
Proceedings of the Boston Society of Natural History, 2:145. Report of the United 
States Exploring Expedition, Mollusca. 
Testa ovalis, depressa, scabra, ad dorsum obtusa, cinereo bifasciata et 
plumose striata; valvis magnis, lateraliter disjunctis; areis lateralibus 
parvis, granulis subquadratis radiantibus arcuatim tessellatis; areis centra¬ 
lists sulcis acutis confertis flexuosis subparallelis longitudinaliter aratis; 
valva antica magna, semicirculari, decemcostata et granulis subquadratis 
insculpta; valva posteriori parva, costa transversali inconspicua subtermi- 
nali: margo latus, filis corneis inaequalibus muscosis indutis. (Gould.) 
Shell depressed, rather broad-oval, obtusely ridged along the back, 
everywhere sculptured. The color is pale olive, ashy about beaks, and with 
an ashy-white band along each side of the dorsal ridge. Valves large, 
narrowing toward the sides, so that their edges do not come in contact; 
the lateral valves are small, slightly raised, coarsely granulated with square 
granules arranged in radiating lines; central areas deeply incised with 
sharp, flexuous, but nearly parallel ridges, the presenting edges of which 
are slightly denticulated; these are arranged along the back in a plumosely 
diverging series, and over the rest of the spaces they are nearly longi¬ 
tudinal ; the spaces intervening between the ridges are indented with little 
alveoli. The anterior valve is large and semicircular, having about ten 
radiating, raised lines, and granulated like the lateral areas; posterior valve 
very small, partially umbonated near its extremity, where it is crossed by 
a faint, transverse ridge, nearly parallel with the margin. Margin broad, 
covered with coarse, moss-like, horny fibers or threads, of unequal size 
and length, flexible when wet, very brittle when dry. Length, 2; breadth, 
1 in. (Gould.) 
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