PARMACELLA. MOLLUSCA. 61 



shield or coriaceous buckler, slightly wrinkled ; four retractile 

 tentacula, the two posterior largest, with the eyes at the sum- 

 mit ; branchial cavity under the shield ; orifice for respira- 

 tion and the anus on the right side. 



The animals of this genus are hermaphrodite. They are very voracious, and de- 

 stroy kitchen vegetables and ripe fruits in the fields or gardens, in which they are 

 found. 



L. cinereus, Lin. Body ash-coloured, often spotted with darker co- 

 lour. 5 inches long. Inhabits Europe in gardens and woods. B. 

 Penn. Brit. Zool. iv. 76. 



L. agrestis, Lin. Body whitish ; tentacula black. Inhabits Europe, 

 in gardens, meadows, and woods. Smaller than the preceding. B. 

 Penn. Brit. Zool. iv. 76. 



L. ater, Lin. (Arion, Daud.) Body black, rounded above, and ru- 

 gous towards the tail. Very common. Inhabits Europe, in gardens 

 and fields. B. List. An. Ag. 131. 



This species is subject to considerable variation of colour, being sometimes found 

 entirely of a brown colour. It is then the L. rufus. 



Gen. 4. PARMACELLA, Lam. 



Body oblong, tumid towards the middle, scutellated, and ter- 

 minated by a compressed tail ; scutellum oval, fleshy, adher- 

 ing at its posterior part, free before, containing a shell, and 

 having a notch in the middle of its right margin ; respiratory 

 and anal orifices under the notch of the scutellum ; four ten- 

 tacula, the two posterior largest ; orifice for generation between 

 the two tentacula of the right side. 



P. Olivier i, Cuv. Body wrinkled, with three longitudinal furrows 

 from the scutellum to the head. 2 inches long. Inhabits Me- 

 sopotamia. A n. Mus. v. pi. 29, fig. 12, 15. 



Gen. 5. ONCHIDIUM, Lam. 



Body oblong, margined on all sides by the mantle ; head pro- 

 jecting, with two cylindrical and retractile tentacula ; mouth 

 destitute of jaws and furnished with two auricular appendages; 

 respiratory and anal orifices under the posterior extremity of 

 the body. 



O. Typha, Buchanan. Body with minute irregular tubercles ; mar- 

 gins of the mantle narrow. 1^ inch long. Inhabits Bengal. 

 Lm. Trans, v. 132. 



SECTION II. HYDROBRANCHLE. 



FAMILY II. LAPLYSIACEA. 



Branchiae placed in a particular cavity towards the posterior 

 part of the back, and covered by an opercular scutellum ; 

 with tentacula. 



The Laplysiae resemble large snails, but with the body thicker and broader to- 

 wards the posterior part, and the margin of the mantle larger. The head projects, 



