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. PI. 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. PL 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. 



Tamaulipas, Mexico. 



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



Arcuately rimate, somewhat solid, diaphanous, lightly costulate, 

 whitish (denudated), suture subimpressed ; whorls 5?, 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. 



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, subpiicate 

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

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



