296 HELICIGONA. 



belong to the Helicidce, but even this is doubtful. It occurs in com- 

 pany with Stomatopsis, a peculiar genus of Melanopsidce, in beds 

 considered to lie at the base of the Eocene. The claim of Obbinula 

 to kinship with Obba is, there can be little doubt, an illusion. 



Genus HELICIGONA Ferussac, 1819. 



=Helicigona (FER.) Risso,-f- Chilotrema and Arianta Leach, 

 1831,+ Chilostoma, Latomusand Isognomostoma FITZ., 1833,-f- C*in- 

 gulifera, Corneola and Lenticula HELD, 1837,+ Campylcea BECK, 

 1837, -\-Sterna ALB., 1850,-f .EYo?ia ADS., 1855, etc., etc. 



Shell usually depressed-globose, varying to globose-turbinate or 

 lens-shaped, usually umbilicated, of moderate or large size; surface 

 smooth, costulate, granulate or hairy, corneous or brown ; unicolored 

 mottled or streaked, and either with a single supra-peripheral band 

 or with one above and one below this, or bandless. Aperture 

 oblique, lunate or oval, the lip expanded, reflexed below and dilated 

 at columellar insertion. Type H. lapicida L. (see pi. 43, figs. 19- 

 25, 27, 28, 31-35, 42, 46). 



Animal externally as in Helix. Jaw strong, with 2 to 16 stout 

 convex ribs, dentating the cutting edge. Radula as in Helix, the 

 ectocones sometimes developed on middle and lateral teeth, some- 

 times represented by lateral continuations of the mesocone. 



Genitalia (pi. 62, all figs.) having the penis short, continued in 

 an epiphallus upon which the retractor is inserted, and ending in a 

 well developed, spirally twisted fiagellum. Dart sack single, inserted 

 rather high on vagina, containing a curved dart with round shaft 

 and flat, 2-bladed head ; the base not coronated. Mucus glands 2, 

 long and tubular, often bifid ; inserted on vagina near base of dart 

 sack (but in H. quimperiana there are 3 triangular lobes on each 

 side). Spermatheca small and globose, on a long duct ; cliverticulum 

 long, larger than spermatheca-duct, connected with the uterus 

 throughout by a broad thin membrane (shown in figs. 16, 18, re- 

 moved in the other figures on pi. 62). See pi. 62, fig. 16, H. rha r - 

 iica; fig. 17, H. cingulata; fig. 18, H. planospira ; fig. 19, H. per- 

 sonata; figs. 20, 21, H. lapicida; figs. 22, 23, H. arbustorum; figs. 

 24, 25, 26, 27, H. quimperiana'). 



Distribution ; Europe, from the Pyrenees and Greece to Sweden 

 and England. For geological distribution see under Chilostoma and 

 the extinct subgenera. 



