HELIX-AMPELITA. 33 



Group of H. xyster a VaL 



The periphery is very acutely keeled ; the peristome narrowly 

 expanded or not expanded above, narrowly reflexed beneath. I have 

 not seen sufficient material to properly analyze this group of species, 

 some of which are narrowly, some widely umbi Heated. 



H. NOVACULA Martens. PI. 6. figs. 75, 76, 77. 



Shell broadly umbilicated, carinate, lens-shaped, somewhat striate, 

 unicolored, brownish-black ; spire planate ; suture superficial ; whorls 

 scarcely 5, rapidly widening, the first very small and a little 

 sunken, the following acutely keeled, the last whorl about equally 

 convex above and below, only moderately convex, not de- 

 scending in front, the keel becoming more obtuse toward the 

 aperture ; the base obtusely angular around the very wide um- 

 bilicus. Aperture very oblique, ear-shaped, leaden bluish within ; 

 peristome narrowly expanded, the upper margin curving a little for- 

 ward in the middle, not expanded, the basal margin slightly arcu- 

 ate, forming an angle with the short, obliquely ascending columellar 

 margin. The aperture has two blunt angles ; one at the periphery, 

 the other at the base of columellar. (Martens.*) 



Alt. 16, greater diam. 45, lesser 35 mill. ; aperture, width 21 o, ob- 

 lique alt. 17 mill. 



Madagascar. 



H. novaeula MTS. Novitates Conch, v, p. 181, 1. 152, f. 4-6. " H. 

 lanx var." Ferussac, Histoire, t. 62 A, f. 8, 9, 10. 



Of this species I have seen but one example. It is irregularly 

 malleated on the last two whorls above, and the base has numerous 

 spiral striae about as coarse as the wrinkles of increment. Under 

 a lens close microscopic spiral striae became visible, both above and 

 below. They are very superficial and rather unevenly developed. 

 I refer to novaeula the figures 83, 84, 85, of pi. 6 copied from Fer- 

 ussac. 







H. XYSTERA Valenciennes. PI. 11, figs. 36, 37, 38. 



Shell umbilicate, orbicular, depressed, very acutely carinated, 

 thin, diaphanous, olive-brown ; suture not at all impressed ; whorls 

 4, plane, the last convex beneath, subangular around the funnel- 

 shaped umbilicus ; aperture very oblique, depressed, irregular; per- 

 3 



