220 
LIMN^AD^. 
stoma; A. meridionalis ; A. costatus; A. albus; A. striatus; 
A. Tinei; and A. Fabrei. Bourg. in Jour. Conch. 1853, 
187. — A. riparius. Desm. Bull. Soc. Philom. 1814, 19. t. 1. 
f. 2. — A. capuloides. Jan, in Risso, Mai. Com. 37. t. 1. 
f. 7. — A. deperditus. Dupuy.^ Hist. Moll. 494. t. 26. f. 4. — 
A. vitraceus, and A. striatus. Morclet, Moll. Port. 87. t. 8. 
f. 3, 4. — Ancilus fluviatilis, and sinuosus. Brard. Coq. Par. 
200. t. 7. f. 3, 4. — Ancylus sinuosus. Gras^ Moll. Franc. 
t. 5. f. 8. — A. (Ancylastrum) fluviatilis. Moq. Tand. Moll. 
Franc, ii. 484. t. 35. f. 5—38. t. 36. f. 1—49. 
Var. 1., with slight longitudinal striag. 
In streams and rivulets attached to stones. 
Animal greyish. 
Shell about a quarter of an inch in diameter, and 
nearly as much in height, semitransparent, light 
horn-colour, covered with a dusky green skin slightly 
marked with concentric stride, inside bluish white, 
glossy ; the crown slightly curved downwards. 
The shells of these animals are modified in form 
and elevation according to the surface of the sub- 
stance to which they may happen to be attached, as 
in the marine Patellce ; hence the Continental natu- 
ralists have made them into several species depend- 
ing on the elevation of the cone of the shell, the 
more or less concave form of the different margins 
of the aperture, the acuteness or bluntness of the 
apex, and the strength of the radiating strise. 
4. Yelletia. (Lake Limpet.) 
The animal like Ancylus^ but dextral ; the shell 
oblong, compressed, conical, with the apex rather 
behind the middle, bent to the left, as in other 
dextral shells ; mouth elongate ; orifices of re- 
spiration, &c., on right side of mantle. 
