4 CLASS GASTEROPODA. 
tumid, and the side of the columella almost concave. The 
shell will not receive the entire animal, and it might almost be 
considered as a large-shelled testacella. Its inferior tentacula 
are very small, and it lives on the plants and shrubs which 
line the borders of rivulets, a circumstance which has caused 
the genus to be considered as amphibious. Swccinea amphi- 
bia, Drap. (Helix putris, L., &c.) 
CLAUSILLA, Drap. 
These mollusca formerly belonged to the genus Turbo of 
Linneus, from which it has been found necessary to separate 
them, in order to approximate them to the terrestrial helices. 
The shell is long, slender, and pointed ; the last whorl in the 
adult narrowed, compressed, slightly detached, and terminated 
by a complete aperture, with a tumid margin, frequently den- 
tated, or furnished with lamine. In the contraction of the 
last whorl we usually find a little plate, bent into an §, the use 
of which to the living animal is unknown. 
The species are very small, living in masses at the foot of 
trees, &c. A great many of them are reversed. (Turbo per 
Versus Lin., &c. &c.) 
ACHATINA, Lam., 
Necessarily separated from the bulle of Linneus, and placed 
here. The aperture of the oval or oblong shell is higher than 
itis broad, as in the bulimi, but wants the tumid margin; the - 
extremity of the columella also is truncated, the first indica- 
tion of the emarginations, which we shall find in so many 
marine gasteropoda. ‘These achatine are large helices, which 
devour trees and shrubs in hot countries. (Bulla zebra, Lin., 
Chem., &c.) 
Montfort distinguishes such as have in the last whorl a cal- 
lus or peculiar thickening (Lzguus, Mont.) ‘This whorl is 
proportionably lower in them than in the others. (Bulla 
virginea, L., &c.) 
