98 CONCHOLOGY. 
short spire, the last whorl very large; aperture large, rounded 
oval; the left margin arched, slightly involute. Inhabits dry 
places of Europe. Three species. 
Vitrina parilis. Vitrina dentilis. 
V. pellucida. 
3. Genus Testacella. Pl. X. 
Animal. Body creeping, elongated, snail shaped, having a 
shell placed on the posterior extremity ; four tentacula, the two 
longest with their eyes at their tips; respiratory organs behind. 
Shell. Very small, external, ear-shaped, apex absolutely spiral, 
aperture very large and oval, left edge sharp and rolled inward 
behind. Inhabits the middle provinces of France. Two species. 
Testacella Haliotidea. Testacella Neritoidea. 
4. Genus Parmacella. _ Pl. X. 
Animal. Body creeping oblong; middle of the back mode- 
rately 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, wider 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. Parmacella Cuvierii. 
5. Genus Onchidium. Pl. X. 
Animal. Body oblong, creeping, marginated on all sides; 
head projecting, the lower part with a prominent margin, two re- 
tractile, cylindrical, tentacula; two auriform appendages, nearly 
lateral; mouth beneath, destitute of maxillary processes; respira- 
tory orifices distinct, under the extremity of the body. 
Destitute of a shell. Inhabits the gardens of Europe. Two 
species. 
Onchidium Typhe. Onchidium Peronii. 
