HELIX-STEGODERA. 9 



Section III. TRIHELIX Ancey, 1887. 



Trihelix ANC. in The Conchologists' Exchange, May, 1887, p. 64. 

 Cepolis (in part) of authors. 



To the type of Trihelix, H. horrida, I have added two Chinese 

 species which seem to belong here rather than with H. triscalpta. 

 This section is closely related to Mollendorffia ; the latter name has 

 priority. 



H. HORRIDA Pfeiffer. PL 1, figs. 9, 10, 11. 



Shell broadly umbilicated, depressed, spire concave, aperture tri- 

 angular, lip 2-toothed. 



Discoidal, decidedly concave above, rather thin, light brown in 

 color. Surface dull, with very minute and sparsely scattered granules, 

 visible only under a lens, and small tubercles arranged in quincunx, 

 standing about one mill, apart, each one bearing a. stiff hair or bristle 

 from J to 1 mill, in length. Spire sunken, apex rather coarse, plan- 

 orboid ; whorls 4i, very convex, the last more than double the width 

 of the preceding, very convex above and below, deeply descending 

 toward the aperture, having a deep pit behind the lip above, and 

 another a short distance preceding it, both above the periphery ; on 

 the base there is a deep pit partly concealed by the expanded lip, 

 and a groove running obliquely into the umbilicus from it. Aper- 

 ture ,very oblique, subtriangular, liver-brown, peristome reflexed all 

 around, parietal margin a little elevated, the upper lip bearing a large 

 tubercular tooth, the straight basal lip a similar one ; there is also a 

 deep-seated tubercle within the mouth at the position of the second 

 supra-peripheral pit of the outside. Umbilicus broad, funnel-shaped. 



Alt. 8, greater diam. 19, lesser 14? mill. 



Laos Mts.j Cambodia. 



H. horrida PFR. Proc. Zool. Soc. London, 1862, p. 272, t. 36, f. 15 ; 

 Monographia v, p. 395 ; Novitates Conchol. iii, p. 399, t. 92, f. 17- 

 19. DOHRN, Continuation of Kiister's Conch yl. Cab., p. 579, t. 170, 

 f. 8-10. 



A peculiar species, distinct in its concave spire, broad umbilicus 

 and hairy cuticle. The single specimen before me agrees in all 

 respects with Pfeiffer's original description. 



H. BISCALPTA Heude. PI. 1, figs. 25, 26, 27. 



Shell moderately umbilicated, irregularly discoidal, the spire plane, 

 apex subconcave, whorls 5, cylindrical, much compressed ; epidermis 



