96 GASTEROPODA. 



Ge7ius G.—'DOhABEhhA.—LamarcL 



Generic Character. — Body creeping, oblong, narrowed in fronts 

 and posteriorly widened ; the area round, sloping, and obliquely 

 truncated ; with the margins folded over the back ; with 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 XIII. 

 fig. 30. Base thick, callous, and subspiral ; dilated above, thin, 

 and wedge-shaped. Inhabits the Indian ocean, at the Isle of 

 France. 



Genus 7.—'LAFhYSlA.—Linnaus. 



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 tentacula ; 

 the dorsal shield semicircular, sub-car tilaginotis, adhering on one 

 side, and covering the branchial cavity ; and orifice placed be- 

 hind the branchiae. 



Laplt/sia radiata. — The Radiated Laplysia. Plate XIV. 

 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. — Liiinceus. 



Generic Character. — Body oblong-ovate, slightly convex; 

 divided into two transverse portions above, and having the man- 



