110 GASTEROPODA. 



Genus 6.— T>OLABELL A,— Lamarck. 



Generic Character. — Body creeping, oblong, narrowed in 

 front, posteriorly widened, and there truncated obliquely by 

 an orbicular inclined plane ; the margins folded over the 

 back ; four somewhat tubular tentacula, disposed in pairs ; 

 branchial operculum enclosing a shell; anal orifice situated 

 on the back, near the branchise, in the middle of the orbicu- 

 lar disk. Shell oblong, slightly arcuated, thicker, callous, 

 and somewhat spiral, on one side, 



Dolabella Rumphii. — RuMPHius's Dolabella. Plate 



XIII. fig. 30. Base thick, callous, and subspiral ; dilated 

 above, thin, and wedge-shaped. Inhabits the Indian ocean, 

 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 tentacula ; the dorsal shield semi- 

 circular, sub-cartilaginous, adhering on one side, and cover- 

 ing the branchial cavity ; anal orifice placed behind the 

 branchiae. 



Laplysia radiata. — The Radiated Laplysia. Plate 



XIV. fig. 25. Nearly round, left margin somewhat re- 

 flected ; outer lip acute ; yellowish horn-coloured, with 

 brown radiations, and two concentric bands. 



TRIBE III. BULLACEA. 



The branchite situated in a particular cavity, near the 

 posterior region of the back, and covered by the mantle ; 

 no tentacula. 



