Animal. Body creeping oblong; middle of the back moderately convex, and shield-shaped; hind part in form of a tail, laterally compressed, acute above; shield ovate, fleshy, adhering at its posterior part, free before, enveloping a shell, with a notch in the centre of its right margin; four tentacula, two posterior largest; respiratory organs, under the notch of the shield, placed between the two tentacula of the right side.
Shell. Ovate, left margin broad and reflected; right margin reflected at top and acute beneath; very thin and pellucid, of a pale yellowish-brown. Inhabits the gardens of Europe. Two species.
- Parmacella Olivieri.
- P. Cuvierii.
5. Genus Onchidium. Pl. [X].
Animal. Body oblong, creeping, marginated on all sides; head projecting, the lower part with a prominent margin, two retractile, cylindrical tentacula; two auriform appendages, nearly lateral; mouth beneath, destitute of maxillary processes; respiratory orifices distinct, under the extremity of the body.
Destitute of a shell. Inhabits the gardens of Europe. Two species.
- Onchidium Typhæ.
- O. Peronii.
FAMILY VII.
Colimacea. Eleven genera.
1. Genus Helix. Pl. [X].
Animal. Of a slightly variable form, the mantle forming at its free edge a kind of ring or thick collar, especially in front, and faintly divided into two lips; foot oval, plane, smooth beneath, inflated and granular below, joined to the visceral club by a narrow peduncle; head sufficiently distinct; anterior tentacula very evident and inflated at top, the posterior very long; the mouth a vertical cleft provided with two labial lobes, a sort of marginal tooth, with a small, oval, lingual club.