GASTEROPODA. 95 



phanous, slightly wrinkled, and of a pale straw-yellow colour. 

 Inhabits gardens in Britain and France. 



Genus4^. — FARM ACELh A.— Lamarck. 



Generic Character. — Body creeping, oblong; middle of the 

 back moderately convex, and shield-shaped ; the hind part in the 

 form of a tail, laterally compressed, and acute above ; shield 

 ovate, fleshy, adhering at its posterior part, and free before, en- 

 veloping a shell, and having a notch in the centre of its right 

 margin ; having four tentacula, the two posterior the largest ; 

 respiratory and anal orifices under the notch of the shield, and 

 the orifice for generation placed between the two tentacula of 

 the right side ; a terrestrial mollusca. 



Parmacella calycutula. — The Cup- Shaped Parmacella. 

 Plate XIII. fig. 31. Ovate; left margin broad and reflected, 

 right margin reflected at top and acute beneath j exceedingly 

 thin, transparent, and of a pale yellowish-brown. 



Genus 5.— ONCHIDIUM.— Zamarc/i. 



Generic Character. — Body oblong, creeping, marginated on 

 all sides ; head projecting, the lower part with a prominent mar- 

 gin ; two retractile, cylindrical tentacula ; two auriform appen- 

 dages, nearly lateral ; mouth underneath ; destitute of maxillary 

 processes ; the respiratory and anal orifices distinct, placed un- 

 der the extremity of the body. Destitute of a shell. 

 Annals du Museum, V. p. 38. plate 6. 



Section II. — Hydrobranchi^. 



The branchiae formed in filaments or laminaj, and pectinated 

 or tufted. The animals respire in water. 



TRIBE II. LAPLYSIACEA. 



The branchiae placed in a particular cavity, situated near the 

 posterior region of the back, and covered by an opercular shield ; 

 the animals possessing tentacula. 



