HELlCINiE. 185 



Sub-gen. nenia, II. and A. Adams. 



Shell ribbed or striated ; lunule none ; palatal plica single, 

 superior; spiral lamella continuous; last whorl protracted, 

 rounded at the base; peristome continuous, reflexed. 



epistomium. Kiist. tridens, Chem. 



Sub-gen. mentissa, H. and A. Adams. 



Shell more or less smooth, not ribbed, horny ; lunule obsolete; 

 last whorl with a single basal crest. 



acridula, Ziegl. Duboisi, Charp. 



canalifera, Rossm. strumosa, Friv. 



detersa, Ziegl subtilis, Parr. 



Sub-fam. HELICIN^E. 



Shell globular or convex ; spire short, the last whorl 

 much larger than the others, composing nearly all the shell ; 

 umbilicus covered or open ; aperture regular, semilunar, 

 generally without teeth ; peristome thickened or reflected. 



Genus STREPTAXIS, Gray. 



Shell urnbilicated, irregular, globosely depressed, base 

 shining, polished, convex, striated above, the last whorl 

 suddenly enlarged and receding in its axis from those 

 above ; aperture edentulate, or toothed ; peristome expanded, 

 reflexed. 



&yn. Artemon, Beck. 



Ex. S. contusa, Ferussuc, pi. 77, fig. 1. Shell S. con- 

 tusa, fig. 1, a. 



