262 HELICELLA. 



Crenea Risso, 1826. ? TrochoidaoY TVoc/icn'rfea BROWN, 111. Conch. 

 G. B. 1827 (publication not seen). Xeroclivia MONTS., Moll. Terr, 

 Is. adiac. alia Sicil., 1892, p. 25 (for H. pyramidata). Xeronexa 

 MONTS., 1. c. (for H. cumice, calcarata). Xerocochlea MONTS., /. c. 

 (for H. caroni, elata). Trochula SOHLUTER, Syst. Verz., p. 7, 1838, 

 MORCH, Journ. Conch. 1865, p. 386. 



Shell solid and earthy, narrowly umbilicated, trochoidal, with 

 conic spire, narrow whorls and rather flattened base; periphery 

 somewhat angular or sharply keeled. Aperture small, lunate or 

 angular, the lip not expanded, strengthened by a submarginal rib 

 within. Type H. terrestris Penn., pi. 68, fig. 27. 



Jaw with 8 to 18 close, flat ribs (pi. 67, fig. 12, H. terrestris). 



Radula (pi. 67, fig. 16 H. terrestris} with mesocone about the 

 length of basal-plate on median teeth, the side cutting points well 

 developed. Laterals the same, but lacking entocones ; on the transi- 

 tion teeth the inner cusps become bifid, and on marginals the ecto- 

 cone also splits. 



Genitalia (pi. 69, fig. 18 H. elegans} ; dart sacks two, very small. 

 Mucus glands 6. At base of vagina or on the atrium a large sack- 

 like appendicula. Other features as in Helicella generally. 



Mainly a circum-Mediterranean group, distinguished from Obelus 

 by the simpler sculpture of the shell and the characters of genitalia 

 mentioned above. 



The name proposed by Brown in 1827, may prove to have first 

 claim for this group, but I have not seen the original publication 

 and it is variously spelled by the authors who have quoted it. In 

 any case, Turricula must be rejected from the nomenclature of Hel- 

 ices, being preoccupied in Mollusca. 



H. newka Dohrn, iv, 29. H. terrestris Penn., iv, 29. 

 H. newkopsis L. & B. eleyans Gmel. 



H. majoricensis D. & H., iii, 258. trochulus Hartm. 



H. miscella West. H. scitula C. & J., iv, 29. 

 H. caroni Dh., iv, 29. trocliilus Poir. 



v. pyramis Phil., iv, 30. depressa Bk. 



H. elata F.-B., iv, 29. perdepressa West. 



v. dilatata Ben. H. trochoides Poir., iv, 27. 

 H. trochlea Pfr., iv, 30. algira Chier. 



H. sequentiana Ben., iv, 30. solarium Risso. 



