92 CONCHOLOGY. 



Shell. Small, very thin, depressed, terminated above by a very 

 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. PI. 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 aliotidea. Testacella Neritoidea. 



4. Genus Parmacella. PI. X. 



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 ovale, 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. Parmacella Cuvierii. 



5. Genus Onchidium. PI. 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 ; respira- 

 tory orifices distinct, under the extremity of the bod3^ 



Destitute of a shell. Inhabits the gardens of Europe. 'J'wo 

 species. 



Onchidium Typhse. Onchidium Peronii» 



