232 ARIONIDvE. 



Section ARIUNCULUS, Lessona, 1881. Genital orifice anterior 

 to the pulmonary orifice. A. Isseli, Bourg. 



Genus GEOMALACUS, Allman, 1843. 



Animal limaciform, subcylindrical, blunt behind, with a but 

 little developed mucous pore ; mantle anterior, close to the head, 

 concealing a shell-plate ; a distinct locomotive disk ; respiratory 

 orifice on the right anterior margin of the mantle ; genital orifice 

 behind and below the right eye-peduncle. Shell-plate calcareous, 

 ovate, small and solid. Jaw costulated ; lingual dentition as in 

 Arion (PI. 45, figs. 14, 15). 



G. maculosus, Allman. Western Europe. 



Subgenus LETOURNEUXIA, Bourguignat, 1866. 



? No caudal mucous pore. There is a peculiar overhanging 

 process to the side of the body, near the tail. 

 G. Numidicus, Bourg. Algiers. 



Genus ARIOLIMAX, Morch, 1860. 



Animal limaciform, subcylindrical, tapering behind ; mantle 

 anterior, small, concealing an internal shell-plate; caudal mucous 

 pore triangular, elevated ; locomotive disk distinct ; respiratory 

 orifice on the posterior right margin of the mantle ; orifice of 

 combined genital sj'stem below the right anterior free edge of 

 the mantle. Shell-plate solid, flat, longer than wide. 



Jaw ribbed. Lingual membrane with tricuspid centrals, bicus- 

 pid laterals and quadrate marginals (PI. 45, figs. 12, 13). 



A. ColumbianuSj Gould. Pacific States of North America. 



Genus HEMPHILLIA, Bland and Binney, 1872. 



Animal limaciform, blunt before, swollen at centre and attenu- 

 ated behind ; mantle subcentral, large, oval, greatly produced in 

 front, free around its margin, and slightly covering the edge of 

 the shell-plate ; a caudal mucous pore, over which is a hump-like 

 process ; no distinct locomotive disk ; respiratory orifice on the 

 central right margin of mantle ; genital orifice near the right 

 eye-peduncle. Shell mostly exposed, unguiform,subquadrangu- 

 lar, the margins covered by the mantle. 



