216 HELIX-OBBA. 



(4.) Group oj H. horizontalis. A strong, oblique gibbous ridge 

 behind the upper lip ; peristome thickened. Banded ; surface deli- 

 cately striated. 



1. Group of H. lister i. 



Interior of the aperture dark; a single dark baud above and 

 below ; often speckled and spotted. Surface rudely wrinkled or 

 malleated. 



Key to species. 



Edge of the parietal callus not thickened, goldei. 



Edge of the parietal callus thickened, 

 Acutely carinated, lens-shaped, 



An elevated cord on the upper surface; obliquely ribbed, 

 nearly unicolored, calcar. 



No cord above ; speckled ; more or less malleated, 



listeri, gallinula. 

 Obtusely or not at all carinated, 



Elevated, trochoidal, nearly imperforate, papilla, heroica. 

 Depressed, decidedly umbilicate, planulata. 



H. PAPILLA Miiller. PI. 53, figs. 3, 4. 



Shell narrowly urabilicated or imperforate, elevated trochoidal, 

 the height equal to or exceeding the shorter diameter; not cari- 

 nated ; sculptured with rude, strong, irregular wrinkles in the direc- 

 tion of growth-lines, the wrinkles white, interstices chocolate or 

 bluish ; base whiter. 



The form is remarkably elevated, the base rather flattened, swol- 

 len, and then constricted behind the basal lip. It is solid, luster- 

 less, lacking epidermis, having an ill-defined interrupted dark spiral 

 band on the middle of the upper surface of each whorl, and another 

 on the base ; the wrinkles become obsolete around the umbilicus, 

 and the surface is white there ; under a strong lens the upper sur- 

 face shows in places a minute granulation, like the texture produced 

 by pressing a very fine textile fabric upon plastic clay ; and upon 

 the base traces of fine spiral incised lines may often be observed. 

 Whorls 5J, the inner two smooth, horn-colored. Last whorl not 

 carinated except immediately behind the outer lip, deeply descend- 

 ing in front. Aperture subhorizontal, oval, dark within ; peristome 

 white, broadly expanded ; baso-columellar margin reflexed, partly 



