Deep-water Limpets and Chitons. 15 
Cocculina Beant, n. sp. 
Shell elevated, white, thin, resembling in sculpture and 
general features the last species, except in the following par- 
ticulars :—The form of the base is about as in C. Rathbuni; 
but the profile differs widely: the anterior and posterior slopes 
of the present species, instead of being subequal and nearly 
similar, are unequal, the anterior being considerably the longer, 
roundly and conspicuously arched ; the posterior slope is about 
-half as long as the other and deeply concavely excavated ; 
this results from the fact that the apex, instead of being de- 
pressed and nearly central, is elevated, subposterior, and much 
ineurved; like that of the previous species, it bears a scar 
where the (probably spiral) embryonic shell was attached. 
The sculpture resembles that of the preceding species, being 
stronger and more cancellated in some specimens and nearly 
obsolete in others. The very young show proportionally 
stronger sculpture, even slightly spinous at the intersections 
in some specimens. The surface is generally partly eroded, 
probably from the same action as that which so rapidly 
reduces dead shells and corals to a species of grey ooze in the 
deep sea. ‘There seems to be no indication of epidermis in 
this species. Length 8-0, breadth 5-0, height 4:0 millim. 
Soft parts in general as in the last species, except that the 
head and muzzle are much elongated, the sinus behind the 
head deep; gill longer and larger than in C. Rathbunt, pro- 
jecting out on the right side of the head ; tentacles longer and 
foot shorter proportionally than in C. Rathbuni; the mantle- 
margin is much puckered; but this is probably due to the 
alcohol; the margination, which forms a semilunar area at 
the end of the muzzle in the preceding species, in C. Beanti 
is interrupted before the papillose area which here distinctly 
forms the end of the muzzle, the effect of which is to produce 
_ two lappets, one on each side, extending from the end of the 
muzzle to the anterior edge of the foot. ‘There appears to be 
no jaw. 
Dentition.—In this species the bands of uncini are propor- 
tionally longer and wider, and the rhachidian tooth smaller, 
than in the preceding. ‘The rhachidian tooth is small, with 
a tridentate cusp and bifurcate base; it is about half as long 
as and hardly wider than the first three laterals; the latter 
are elongate, slender, with denticulate cusps, the outer is 
rather the shorter in the mature part of the radula; the major 
lateral is longer, with a more slender shaft than in C. Rath- 
bunt, and a proportionally larger, very concave cusp with 
seven or eight denticulations ; the banded uncini are singly 
