132 HELIX. 



Distinguished from the next species by its narrower umbilicus, 

 with its groove and internal lamina ; the latter is only to be seen by 

 breaking the whorl. 



H. PUSTULOIDES, Bland. PL 27, figs. 76-78. 



Widely and deeply umbilicated, thin, delicately striated, horn 

 color, slightly hirsute; whorls 4J, narrow, subangular at the 

 periphery, constricted and suddenly deflected at the aperture ; 

 aperture lunate, with a lamelliform parietal tooth joined to the 

 upper extremity of the lip by a sharp callus, outer lip reflected, 

 thickened within, with two internal teeth and a deep notch between 

 them. Diam. 5'5 mill. 



Alabama, Georgia. 



H. ARIADNE, Pfr. PI. 27, figs. 79-81. 



Shell white, finely ribbed above, smooth beneath ; whorls 5, with 

 impressed suture; body whorl deflected, much constricted and 

 scrobiculate behind the aperture; aperture small, lip thick, much 

 expanded, its extremities joined by an irregular V-shaped tooth ; lip 

 with two stout basal folds converging within, while behind them is 

 a perpendicular broad lamina almost closing the mouth; base 

 convex, showing more than one whorl with a rounded umbilical 

 groove terminating in a minute central perforation. 



Diam. 12 mill. 



Ta maulipas, Mexico . 



H. UNGUIFERA, Mousson. PI. 27, figs. 82, 83. 



Arcuately riniate, somewhat solid, diaphanous, lightly costulate, 

 whitish (denudated), suture subimpressed ; whorls 5J, a little convex, 

 the last shortly descending, bicompressed and subconstricted in 

 front, base smooth, subangulated at the umbilicus; peristome shortly 

 reflected, the margins converging, with a V-shaped parietal tooth, 

 two entering basal teeth, the exterior larger, and two teeth within 

 the outer margin. Diam. 12 mill. t 



Mazatlan. 



Allied to the preceding species, but is distinguished from it and 

 the others of the group by the lower tooth of the outer lip, which is 

 elevated into a sharp projection. 



H. DYSONI, Shuttlew. PI. 28, figs. 88-91. 



Rather widely umbilicated, shining, brownish corneous, subplicate 

 above, striulate below; whorls o-5|, a little convex, the last scarcely 

 descending in front and subangulated on the periphery, base convex, 



