418 
MOLLUSCA. 
truncated; with the margins folded over the back ; four 
somewhat tubular tentacula, disposed in pairs ; branchial oper¬ 
culum inclosing a shell; anal orifice situated on the back, near 
the branchiae.—Shell oblong, slightly arcuated, thick, callous, 
and somewhat spiral on both sides. 
Dolabella Rumphii. — Rumphius’s Dolabella. 
Plate LXXXVI. fig-. 30. 
Base thick, callous, and subspiral; dilated above, thin, and 
wedge-shaped. Inhabits the Indian ocean, at the Isle of France. 
Genus 7.—LAPLYSIA.— Linnceus . 
Generic Character. —Body creeping, oblong, convex above; 
bordered on each side by a broad mantle, which covers the back 
when the animal is quiescent; head and neck elevated ; with 
four tentacula, of which the two upper ones are ear-shaped ; 
the eyes situated near the mouth before the ear-shaped tentacu¬ 
la ; the dorsal shield semicircular, sub-cartilaginous, adhering on 
one side, and covering the branchial cavity; anal orifice placed 
behind the branchiae. 
Laplysia radiata — The Radiated Laplysia. 
Plate LXXXVII. fig. 25. 
Nearly round, left margin somewhat reflected; outer lip 
acute; yellowish horn-coloured, with brown radiations, and 
two concentric bands. 
TRIBE III.-BULLACEA. 
The branchiae situated in a particular cavity, near the poste¬ 
rior region of the back, and covered by a mantle ; destitute of 
tentacula. 
Genus 8.—BULLA.— Linnceus. 
Generic Character .—Body oblong-ovate, slightly convex; 
divided into two transverse portions above, and having the 
mantle slightly folded posteriorly; with visible tentacula ; 
branchiae on the fore part of the back, and covered; anal open¬ 
ing placed in the right side.—The posterior part of the body 
covered by an involute shell, with neither pillar nor spire; aper¬ 
ture extending the whole length of the shell. 
