Mean divergeuce 30°; greatest brcadtli .1 inch; least breadth 

 .09 inch ; height .072 inch. 



Helix diminuta. Shell discoidal ; greenish or pale corneous, 

 with distant transverse raised lamellae; spire slightly elevated con- 

 vexly ; apex obtuse ; whorls four and one-half, rather convex, with 

 a rather deep suture ; aperture orbicular, except as a little modified 

 by the penult whorl ; lip sharp and thin ; umbilicus very wide. 



Greatest breadth .13 inch; least breadth .103 inch; height .05 

 inch. 



Helix apex. Shell discoidal ; whitish ; with microscopic spiral 

 striae ; spire scarcely elevated, convex ; apex very obtuse : whorls 

 four, cylindrical, with a deep suture ; aperture nearly circular ; lip 

 thin and sharp ; umbilicus very wide. 



Greatest breadth .073 inch ; least breadth .005 inch ; height .02 

 inch. 



Helix immunda. Shell depressed conic ; dingy white, some- 

 times greenish and brownish, translucent ; very thin, with very 

 unequal striae of growth ; spire convex, moderately elevated ; apex 

 very obtuse ; whorls five, quite convex, with a deep suture ; aper- 

 ture transversely oval ; lip extremely thin and sharp, reflected in 

 the columellar portion ; umbilicus not very wide, extending to the 

 apex. 



Greatest breadth .52 inch ; least breadth .44 inch ; height .27 

 inch. 



Helix perdepressa. Shell discoidal ; whitish or pale horn col- 

 ored ; with very fine transverse stria; ; spire concave or plane, with 

 the last whorl often descending below the plane of the preceding; 

 apex always depressed into the plane of the spire ; whorls five, an- 

 gular, on the upper side sloping a little below the plane of the spire, 

 with a well impressed sature ; aperture elliptical, a little modified 

 by the penult whorl ; lip thin and sharp ; umbilicus as wide as the 

 last whorl, regularly concave and exhibiting all the whorls. The 

 following are the dimensions of a large specimen. 



Greatest breadth .25 inch; least breadth .215 inch; height .105 

 inch. 



Helix angustispira. Shell somewhat hemispherical ; pale horn 

 colored ; very finely striated transversely ; spire depressed conic, 

 with rectilinear outlines ; apex very small and acute ; whorls five 

 and one half, quite convex, narrow, high, with a rather deep suture ; 

 aperture lunate, obliquely very long and narrow : uudjilicus riithcs 

 small. 



