50 HELIX-AMPELITA. 



shortly, rapidly descending, obliquely dilated ; aperture oblique, 

 lunate; peristome thickened, white, broadly reflexed, margins ap- 

 proximating, joined by a white lamina; the outer excavated, a little 

 campanulate, basal arcuate, obscurely nodiferous, columellar very 

 short. Alt. 19, greater diam. 33^-36, lesser 25-28 mill. The shell 

 is depressed-convex, a little orbicular, of a russet color, sometimes 

 without epidermis and white ; ordinarily unicolored, but sometimes 

 ornamented with scarcely apparent bands. Shell covered with regular 

 striae and longitudinal lines, visible only under a lens. Whorls of 

 tho spire convex, the last with a more or less marked depression. 

 Umbilicus quite wide, showing usually two-thirds of a volution, 

 terminating in a minute, deep perforation. Peristome white, well 

 expanded, especially on the outer side. (Mabille, 1. c., p. 146.) 



Madagascar. 



Evidently close to H. lamarei Mke. 



H. polydora Mabille. Shell moderately but profoundly subper- 

 viously umbilicate, depressed -orbicular, convex, a little thickened, 

 very solid, shining, white, ornamented with purple-chestnut zonules ; 

 spire a little prominent, apex minute, obtuse, smooth, concolored ; 

 whorls 5, subregularly and very rapidly increasing, convex-depressed, 

 separated by a distinct, linear suture ; the last large, turgid at suture, 

 impressed at periphery, then angulately rounded, convex beneath, 

 a little angular around the umbilicus, at the aperture dilated and 

 very shortly deflexed ; aperture oblique, slightly lunate, irregularly 

 oblong-ovate ; peristome white, a little thickened, reflexed, margins 

 approximating, joined by a thin callus ; outer margin sinuate, broad- 

 ly expanded ; basal margin incurved, subnodose ; columellar oblique, 

 incurved and thickened. Alt. 16, greater diam. 32, lesser 25 mill. 

 A very shining shell, of a beautiful porcelain-white color, ornamen- 

 ted with three purple bands, two above, one below. Stria3 fine, 

 scarcely visible ; spire visibly convex ; last whorl angular at its be- 

 ginning, rounded at its termination, with a well-marked but narrow 

 depression situated between the two superior bands ; base convex, a 

 little angular around the umbilicus, which is well opened, deeply 

 penetrating, but more contracted than in H. madera. (Mabille, 1. c., 

 p. 148.) 



Madagascar. 



Allied to H. hova Angas. 



H. madera Mabille. Shell moderately umbilicated (umbilicus 

 subpervious), subconoid-depressed, pretty thin but solid, shining, 



