40 HELIX-AMPELITA. 



malleated ; penultimate more or less high proportionally to the 

 breadth of shell, last whorl more convex beneath, base somewhat 

 saccate and inflated toward the aperture, then transversely im- 

 pressed and constricted ; whorl above slowly, and for a long distance 

 deflexed. Aperture much broader than high, very oblique, sub- 

 rectangular-elliptical, a little excised ; peristome all around reflexed, 

 margins approximating, joined by a thin callus, right margin curved, 

 either white or often smoked with brown; columellar margin 

 straightened, white, subreceding above. 



Alt. 28, diam. 57^-63 mill.; aperture, alt. 24-25, breadth 32^-35 

 mill. (Boettger.~) 



Northwestern Madagascar and Nossi-Be. 



H. lanciformis BOETTGER Nachrichtsbl. d. deutsch. Mai. Ges. 

 1889, p. 47. 



The prominent distinctive characters are the small spire ; the in- 

 conspicuous thread which seems, so as to speak, to be laid upon the keel 

 which is indicated upon the middle of the last whorl ; the narrow, more 

 elongated aperture, the constantly present oblique wrinkling of the 

 middle part of the last whorl, and especially the broad yellow or 

 white spiral band, usually sharply defined, which encircles the um- 

 bilicus. 



Var. NOSSIBEENSIS Boettger. 



Differs from the type in the subexcentric umbilicus, the last whorl 

 planate-sloping above the middle, last whorl less inflated behind the 

 aperture and less deeply constricted, aperture longer, narrower, more 

 produced and rostrate, right margin curved, brown, columellar mar- 

 gin straighter, whitish. 



Alt. 25-28, diam. 53-60 mill; aperture, alt. 21-23, breadth, 31- 

 34 mill. (Boettger.) 



Rare, in the forest of Loucoube, Island of Nossi-Be. 



Group of H. duvallii Petit. 



Compact forms, with moderately wide umbilicus, narrowly ex- 

 panded thick blunt lip, its terminations converging and joined by a 

 heavy parietal callous. H. schaerfice and H. percyana may perhaps 

 belong near the following three species. H. atropos also seems to be 

 similar. Of these forms I have seen only H. duvallii. 



