48 HELIX. 



H. RAVIDA, Benson. PL 10, fig. 15. 



Narrowly umbilicated, thin, slightly rugosely plicate, with obsolete 

 spiral lines, light olivaceous brown or yellowish brown ; whorls 6, 

 convex, the last inflated, slightly descending in front; peristome 

 simple, acute, columellar margin dilated and reflected. 



Diam. 33 mill. 



Middle and Northern China. 



H. helvacea, Phil, is a synonym. 



Var. LINEOLATA, MollendorfF. 



More conical, decussated, corneous yellow, aperture yellowish 

 roseate. Diam. 23 mill., Alt. 26 mill. 



Near PeTcin and Kalgan, China. 



Mr. E. A. Smith, in a paper on Loo Choo Shells (Proc. Zool. Soc. 

 317, 1887) remarks: H. despecta, Gray, (Manual, iii, 211), H. ravida, 

 Benson, H. Redfieldi, H. Sieboldtiana, Pfr. and H. assimilis, A. Ad., 

 are all very much alike and might well be considered varieties of 

 one and the same species. In the series of eighteen specimens from 

 Loo Choo I find considerable differences in form, some being much 

 higher and more globose than others. One example is of a peculiar 

 purplish brown color, and another is remarkable in having a thick- 

 ening or limbus within the lip. 



H. BURTINII, Desh. Fig. 16. 



Smaller than H. ravida, with imperforate axis, columella thin, 

 cylindrical, not dilated at the base. Diam. 23 mill. 



China. 



This may be only a phase of H. ravida, as suspected by some 

 conchologists, but I think its distinctive characters sufficient. 



H. PHRAGMITIUM, Heude. PI. 10, fig. 20. 



Perforation covered or nearly covered, shell thin, fragile, pellucid, 

 lightly cancellated, greenish or brownish; whorls 6, convex, the 

 last rapidly increasing; peristome simple, acute, thin, columellar 

 margin dilated, reflected. Diam. 23 mill. 



Blue River, China. 



This form has been referred to H. Burtinii Desh., but is more 

 depressed and differs in the umbilicus. 



H. ASSIMILIS, H. Adams. PI. 10, fig. 22. 



Openly umbilicated, thin, irregularly striated and very closely, 

 slightly decussated, subpellucid, shining, light fulvous; whorls 5 i 



