370 MOLLUSCA. 
Suet solid, ashy-white, erect, elevated conic, with the outline 
somewhat convex ; the apex central, elevated, acute, and reaching for- 
wards and upwards. Surface radiated with numerous nearly equal 
raised lines, which are decussated by much finer concentric strie : fis- 
sure small. Aperture rounded-oval, the margin expanded and thinned 
to a sharp edge, which is minutely crenulated. The fornix is circu- 
larly arched over a short sulcus, and in front of it, near the summit, 
runs a transverse rib, leaving between it and the fornix, on either 
side, a triangular pit. The summit also appears to be filled with 
callus. Colour greenish-white within. 
Length nine-twentieths of an inch; breadth eight-twentieths of an 
inch; height eight-twentieths of an inch. 
Dredged at Puget Sound. Lveutenant Case. 
Nearly as large, but differing altogether from the preceding in its 
shape, sculpture, and the interior rib, which props the fornix, and 
leaves two pits, which, with the fissure, would suggest the openings for 
the eyes and nose in the human skull. The little thread-like ribs are 
more or less alternately larger and smaller. 
It is not a little singular that this small genus, comprising so few 
species, should be so widely distributed, being found in the temperate 
seas north and south of the Equator in both the Atlantic and the Pacific. 
Figures 476, 476 a, 476 8, dorsal, interior, and profile views of the 
shell; 476 c, details of sculpture, magnified. 
Rimuxa conica (D’Orsieny), Voy. dans l’Amer. Merid., 471, pl. 
78, f. 10, 11. 
AntmaL colourless, foot oblong-oval, narrow; head very large, not 
forming a proboscis on the under side, as in Patella, but exhibiting a 
circular orifice, in which is seen the true mouth, vertical, with a pro- 
tuberant fleshy lp on each side; the tentacles originate from the 
lower and back part of the head, very long and slender, having the 
eyes very large and bright on a lateral enlargement, at the inferior 
third, immediately behind which, like a sort of spur, arises a second 
short, conical pair; these and the tentacles proper are continually in 
