HELIX-STEGODERA. 7 



anteriorly, then suddenly deflexed, becoming free from the preceding ; 

 aperture trigonal or squarish, nearly horizontal, with teeth on the 

 basal and outer lips, and on the elevated parietal margin ; peristome 

 expanded all around. Type, H. trisinuata Mart. 



South-eastern China, Tonquin. 



Section I. STEGODERA Martens, sensu stricto, 1876. 



Stegodera MART, in Novitates Conchologicse iv, p. 150, 1876. 



Stegodera in the restricted sense comprises only one species of 

 Central China, remarkable for its sinistral convolution, distorted last 

 whorl, crescentic aperture and narrow throat. It may possibly be 

 allied to such species as H. arbusticola and rupelli Desh., which are 

 dark colored, granulate forms, but I regard this as doubtful. The 

 affinity with H. triscalpta seems much nearer. 



H. ANGUSTICOLLIS Martens. PI. 1, figs. 15, 16, 17. 



Shell sinistral, umbilicate, depressed, last whorl irregular, its latter 

 half straightened, embracing and covering part of the two preceding 

 whorls of spire. 



Discoidal, solid, opaque, slightly shining, rich chestnut brown ; 

 surface densely, minutely granulated on the last whorl, the whorls 

 of the spire arcuately striate, more shining, not granulate. Spire a 

 little convex ; apex blunt, whitish ; whorls 5, quite convex, separated 

 by well-impressed sutures, slowly widening, the last whorl very wide, 

 its latter portion (nearly one-half) straightened, very tumid, embrac- 

 ing the preceding and part of the next inner whorl, deeply descending 

 anteriorly to about the middle of the preceding whorl. Aperture 

 extremely oblique, narrowly lunar, dark within, the peristome nar- 

 rowly reflexed, brown above, white on the baso-columellar portion ; 

 parietal wall with a mere wash of transparent callus. Throat 

 extremely narrow. Umbilicus deep, cylindrical. 



Alt. 13, greater diam. 28-30, lesser 22 mill. 



On the Lake Po-yang, Province of Kiang-si ; Right bank of the 

 Yang-tsze River, between Kiou-kiang and Hwang-tschou. 



H. angusticollisM.A.RT., Sitz. Ges. nat. Fr. Berl., Jan. 1875, p. 2 ; 

 Mai. Bl. xxii, 1875, p. 185. PFEIFFER, Monographia vii, p. 449 ; 

 Novitates Conch, iv, p. 149, t. 184, f. 7-10. HEUDE, Moll. Terr. 

 Vallee Fleuve Bleu, p. 36, t. 15, f. 8. 



