MANUAL OF CONCHOLOGY, 



FAMILY HELICIDJE, Vol. IV. 

 Genus HELIX, Linn. (Continued.) 



Subgenus XV. STEGODERA (Martens) Pilsbry. 



Under the above title may be grouped a number of peculiar 

 Helices, figured on pi. I of this volume. They range from the Yang- 

 tsze River in Central China to Cambodia. These shells have a certain 

 similarity to the American groups Cepolis and Polygyra, and to the 

 Indian and Ceylonese Plectopylis and Gorilla. But they are in all 

 probability a distinct phylum, which may be given the same rank as 

 the assemblages called "groups" in the previous volume of this 

 MANUAL. 



The anatomy is unknown. The shells are depressed, umbilicated, 

 dark colored, granulate, often with hairy cuticle. The aperture is 

 very oblique, and always obstructed in some way ; either by teeth or 

 folds, or by a constriction of the last whorl. The systematic position 

 of the subgenus can only be determined by a study of the soft parts. 

 I have used Martens' name Stegodera in an extended sense, as it is 

 the oldest proposed for a member of this group of forms now for the 

 first time associated. 



The species of the subgenus may be separated into two main 

 divisions; (1) those with crescentic or rounded-lunar aperture, and 

 (2) those with triangular mouth. Further than this, I do not think 

 the several sections proposed have much taxonomic value. They 

 may be grouped thus : 



I. Aperture crescentic or rounded-lunar ; folds or teeth if present, 

 not developed from the margin ofperistome; parietal callus very light. 



a. Sinistral, the last whorl distorted ; no teeth or folds within. 



STEGODERA 

 (5) 



