308 Unwersity of California Publications in Zoology  [Vou.14 
“Color soiled whitish, with numerous wide blackish rays. Inside white, 
hole-eallus white, very abruptly truncated behind; margin deeply and sharply 
erenulated. Perforation short-oval, nearly cireular, in front of the middle.’’ 
Height, 26 to 60 mm. 
Occurrence.—At stations D 5702 (3), D5713* (2), D5800 (1), 
D 5808 (1), and questionably at D 5801 (1). 
This keyhole limpet was first listed from the vicinity of San Fran- 
cisco by Wood and Raymond (1891). It is represented among the 
Survey collections by several worn specimens obtained from the middle 
division of the bay in depths ranging from 1334 to 43 fathoms. 
Range—Sitka, Alaska, to San Diego, California (Oreutt). 
Fissurella Bruguiére 
Fissurella volcano Reeve 
Fissurella volcano Reeve (1849), pl. 4, fig. 2; Carpenter (1863), p. 651; 
Pilsbry (1890), p. 156, pl. 62, figs. 16-18; Wood and Raymond (1891), 
p. 57; Arnold, R. (1903), p. 340. 
Description.—This species was described by Pilsbry (1890) as follows: 
“*Shell oval, usually a little narrower in front, the orifice a little in front 
of the middle, oblong, often obscurely tripartite, about one-eighth the length 
of the shell; surface with radiating unequal riblets, often subobsolete. Color 
pink-ashen with 13 to 16 purplish rays, often speckled near the summit. Inside 
white, smooth, frequently with a pink line bounding the callus around the 
perforation; border narrow, dark, alternately pink or purple and gray.’’ 
This species was found within the limits of San Francisco County 
by Wood and Raymond. It was not collected by the Survey. 
Range.—Bolinas Bay, California, to San Hippolite Point, Lower 
California. 
Megatebennus Pilsbry 
Megatebennus bimaculatus (Dall) 
Fissurellidaea bimaculata Dall (1871b), p. 132, pl. 15, fig. 7. 
Clypidella bimaculata, Cooper (1888), p. 235; Arnold, R. (1903), p. 339. 
Description.—This species was described by Dall (1872) as follows: 
*«Shell ellipsoidal when young, subquadrangulate, and a little narrower in 
front than behind, when adult. Aperture the same shape as the shell, slightly 
encroached upon in some specimens by a point on each side. External surface 
furnished with radiating, rounded costae, not bifurcating but widening slightly 
towards the margin. These are crossed by evident but not very strong lines 
of growth, which, in some individuals, are rather 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 fasiculus 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. 
