PULMONATA. 51 



Arionidjc, Grai/, Syn. B. M. 1840,1842; in Turtori's Manual, 

 ed. 2. 101, 104, 1840; P. Z. Soc. 1847, 169; Mrs. Gray, 

 Fig. Moll. w. 111. 



Ariouea, Hemnannsen, Index, 81. 



Helix, § Pherepora, Desmoulin, Linn. Soc. Bard. 1824, iii. 



Synopsis of Genera. 



A. Body elongate, attached its whole length to the upper surface 



of the foot. 3Ianile shield-like, simple, entirely enclosing a 

 fiat, oblong, not spiral, shell. Subcaudal gland lunate, trans- 

 verse, horizontal. Ai'ionina. 



1. Arion. Back keeled, attenuated behind. 



2. Geomalacus. Back convex, rounded behind. 



B. Body more or less spiral, jyrominent from the middle of the 



upper part of the foot, and covered with a more or less deve- 

 loped spiral shell, sometimes hidden by the reflexed edge of 

 the mantle. Subcaudal gland linear, perpendicular. 



a. Body and shell subpeltate, very slightly sjnral. 



3. Drusia. Body united to the back of the foot, only sepa- 



rated by a lunate groove behind. Shell quite enclosed, thin, 

 with a small, more solid apex. 



4. GiRASiA. Body united to the back of the foot, only sepa- 



rated by the convex hinder ed^e. Shell partly exposed, 

 ovate, expanded, with solid apex. 



5. Mari^lla. Body free and separate from the back of the 



foot. Shell quite enclosed in a thin mantle. 



b. Body and shell subglobose, distinctly spiral. 



* Shell quite enclosed in the thin mantle which is produced in 



front. 



6. Laconia. Shell subglobose ; spire of few whorls. Mouth 



very large. 



** Shell permanently covered by the reflexed thin edge of the 

 mantle, leaving the central portion exposed. 



7- Parmacellus. Shell thin, depressed. Mouth ver}' large. 



D 2 



