3. Conenyiium. Cuy. 
Entirely aquatic or 
breathing by branchie. 
a. Ampullaria. 
4. Melania. 
ce. Phasianella. 
Double lips notched 
and fringed, each wing 
with three filaments. 
d, Tauthina. (1) 
A vesicular organ un- 
der the foot, like a fro- 
thy ball but solid, which 
admits of floating but 
not of creeping; head 
like a cylindrical trunk, 
mouth with little fangs. 
Pl. 14, fig. 13. 
4. Nenira. Lin. 
Shells with the colu- 
mella straight, the mouth 
semi-circular or semi-el- 
liptic, and closed entirely 
by an operculum. 
a. Natica, Lam. 
Foot large; opercu- 
lum horny. Pl. 47, fig. 
17, 18. 
b. Nerita, Lam. (2) 
Foot moderate ; oper- 
culum stony. Pl. 17, 
fig. 41, 12. 
c. Neritina. 
Foot moderate ; oper- 
culum horny. 
( 67 ) 
2 Long tentacula, 
Tentacula simple. 
Animal not yet de- 
scribed, but probably re- 
sembling the Paludina. 
Animal not wellknown. 
Eyes on two tubercles 
at the outer base of the 
tentacula, 
Eyes at ihe base of the 
tentacula. 
Eyes on stems at the 
side of the tentacula. 
(1) The common species (Helix Janthina, Lin.) List. 572, 24, is a pretty violet- 
coloured shell, abounding in the Mediterranean. 
it sheds a thick liquor of a deep violet colour, which tints tbe sea around it. 
When the animal is touched, 
(2) The opercula of some univalve shells, particularly of the Nerita, are articu- 
lated by ginglymus. 
