6 HELIX-STEGODERA. 



b. Dextral, whorls regular. ; lamellae within outer lip. 



TRAUMATOPHORA. 



II. Aperture trigonal or squarish ; teeth or folds developed from the 

 inner edge of peristome ; the ends of which are joined by a parietal 

 callus. 



a. Parietal callus scarcely elevated, not toothed; spire flat or 



sunken, TRIHELIX. 



b. Parietal wall elevated, toothed ; peristome free, continuous. 



MOELLENDORFFIA. 



The characters of each of these subdivisions are given more in 

 detail in the following. 



Synopsis of Sections of the Subgenus Stegodera. 



Section I. STEGODERA Martens, s. sir. 



Shell sinistral, discoidal, umbilicate ; inner whorls slowly increas- 

 ing, regular ; latter half of the last whorl straightened, covering the 

 preceding whorl above; aperture narrowly lunar, without teeth; 

 peristome narrowly reflexed ; throat very narrow. Type, H. angust- 



icollis Mart. 



Central China. 



Section II. TRAUMATOPHORA Ancey. 



Shell discoidal, umbilicate, spire low, whorls slowly widening; 

 surface granulate ; body-whorl rounded, deflexed in front ; aperture 

 rounded lunar, oblique, with three entering lamellae within the outer 

 and basal lips, their positions marked outside by long grooves. Type, 

 H. triscalpta Mart. 



Central China. 



Section III. TRIHELIX Ancey. 



Shell discoidal, with flat or sunken spire ; umbilicus funnel-shaped, 

 wide; surface granulate, hirsute; last whorl rounded, descending 

 anteriorly ; aperture trigonal, with a tooth on the basal and one on 

 the outer-superior lip, their positions marked by external pits or 

 grooves ; peristome reflexed, continuous. Type, H. horrida Pfr. 



China, Cambodia. 



Section IV. MOELLENDORFFIA Ancey. 



Shell depressed, the spire convex ; umbilicus rather narrow ; 

 surface granulate, hirsute in the young; last whorl descending 



