GASTEROPODA. 



93 



with two subulate tentacles, separated at their bases, and 

 bearing the sessile eyes at their origin externally; pro- 

 boscis long ; tongue linear, armed with teeth, axile dentate 

 with an apical serrated hook, laterals one on each side, 

 very large, broad, hooked, and serrated; foot oblong, 

 obtusely quadrate in front, rounded behind.* — 5 species; 

 also fossil. 



Delicate shells completely buried in the large mantle of 

 the animal, consequently devoid of any colour. Found 

 on the British shore, also on those of New Zealand, the 

 Philippines, the Mediterranean, &c. 



Section II. 



The animals of the following families have no distinct 

 breathing tube, and the eyes are placed at the base of the 

 tentacula. The shells have no notch or canal, with the 

 exception of Cerithium and Melanopsis, but they cannot 

 be included in the foregoing families. 



Family 11. — TURRITELLACEA. 



The animals have a snout-shaped head, two long ten- 

 tacula, on the outside base of which, the eyes are placed ; 

 the mantle is fringed at the edge; the tongue is small, 

 linear, in the middle one row of teeth, and on each side 

 it is beset with three rows of hooks. The shell is turret- 

 shaped, witli numerous whorls, the aperture oval, or 

 rounded, the lower part of a few having a notch or even 

 a canal ; the horny operculum varies in character. 



Tukkitella. Lam. (Haustata Montf. ; Terrebellum 



* Forbes's British Moll. 



