GEOMITRA-HELICELLA. 245 



Swainson in his first reference to this group figures the H. tiarella, 

 but does not mention it by name. In his later reference he con- 

 fuses tiarella with the figure and description of H. bicarinata Sow., 

 but his diagnosis shows clearly the species intended. 



G. tiarella W. & B., iv, 35. G. grabhami Woll. 



G. moniziana Paiva., iv, 34. G. delphinuloides Lwe., iv, 34. 



G. coronula Lwe., iv, 34. G. delphinula Lwe., iv, 44. 



Genus HELICELLA Ferussac, 1819. 



Helicella FEB., Tableau Syst. de la Fam. des Lin^ons, p. 37 

 (fourth group only). Risso, Hist. Nat. Eur. Merid. p. 67, 1826, in 

 part. 



=Xerophila Held, 1837 and of subsequent authors, with Heli- 

 eopsis Fitz, 1833, Zenobia and Jacosta Gray, 1821, etc., etc. 



Shell umbilicate or perforate, with either cylindrical or keeled 

 whorls ; opaque and earthy, white or whitish and usually banded, 

 not hairy ; aperture round-lunate or angular, not very oblique, the 

 lip acute, hardly expanded, thickened within (See pi. 68, figs. 20 to 

 30.) 



Jaw with 4-11 wide, flattened ribs (pi. 67, figs. 12, 14). 



Radula (pi. 67, fig. 13 H. caruance v. gattoi) with teeth of the 

 type usual in ground-snails. Median teeth with weak ectocones or 

 none, laterals with small divergent ectocones. On the marginals the 

 inner cusp is either simple or bifid, outer cusp single or split (see 

 also pi. 67, fig. 16, H. terrestris}. 



Genital system (pi. 69, all figs.) having the penis rather short, 

 continued in an epiphallus bearing retractor, and ending in a short 

 flagellum. Dart sack single or paired, with or without accessory 

 sacks, and containing curved darts which are two-bladed at least 

 toward the point. Mucus glands simple and tubular, several in 

 number or numerous, but inserted individually on vagina. Sper- 

 matheca oval or irregular, borne on a rather short, unbranched 

 duct. Right eye-retractor passing to the left of genital system, not be- 

 tween its branches. 



An exception to the above diagnosis occurs in Theba, where the 

 penis lacks retractor-muscle, and the dart sack is empty (pi. 69, figs. 

 14, 16, 22). In many species a sack-like organ or appendix, of un- 

 known function is developed on the penis or on the atrium ; and in 



