2 
with numerous equidistant, parallel, raised lines revolving upon 
them; suture much impressed; aperture remote frum axis, self- 
lunate, narrow, not expanding; peristome acute, thin; umbilicus 
wide, forming a concave depression of the base, each volution 
visible to the apex; within the aperture, on the external circum- 
ference, are placed from 1 to 3 pairs of minute, conical, white 
teeth, the first pair in sight when looking into the aperture, the 
others more remote: greater diameter 3.5, lesser 3, hight 1.5 mm, 
Hartland, Vermont, common. Oakland, Cal., Idaho, New 
Mexico, Texas. Now placed in the genus Helicodiscus. 
9 Hyalina minuscula 
Shell umbilicated, minute, depressed-convex; epidermis whit- 
ish; whorls 4, convex, not increasing rapidly in diameter, with 
microscopic wrinkles; suture very distinctly impressed; aperture 
nearly circular; peristome thin, acute; umbilicus large, not 
spread, deep, and exhibiting the volutions; base rounded, colu- 
mella with a thin callus; greater diameter 2.5, lesser 2.3, height 
1 mm. 
Hartland, Vermont, rare. This has a wide range, south to 
Yucatan, Mexico, Florida, Texas, Arizona, California, Japan, Cuba, 
and Porto Rico. 
10 Hyalina exigua 
Shell broadly umbilicated, depressed, pellucid, greenish horn 
color, marked with delicate revolving lines, and distant longi- 
tudinal ribs obliquely decussating the incremental striae; spire 
scarcely elevated, apex free from striae; whorls 3.5, convex, the 
last rounded, widely umbilicated below; aperture oblique, trans- 
versely rounded, remote from axis; peristome simple, acute, its 
columellar extremity not reflected; greater diameter 2.5, height 
0.5 mm. 
Hartland, Vermont, rare. Canada, New York, Michigan. 
11 Hyalina viridula 
Shell umbilicated, depressed, thin, fragile; epidermis pale, or 
brownish horn color, wrinkled, shining; whorls 4, the last rapidly 
enlarging toward the aperture; aperture transversely rounded; 
peristome simple, its edge rather thickened, not acute; umbilicus 
small, but well marked and constant; greater diameter 5, lesser 
4.6, height 2 mm. 
Hartland, Vermont, common; a circumpolar species common 
to three continents, reported from Portland, Oregon, Utah, Ari- 
zona, New Mexico, and the shores of the Gulf of Mexico. 
12 Hyalina fulva 
Shell imperforate, subconical thin, pellucid; epidermis 
smooth, shining, minutely striated, amber-colored; whorls 5 or 
6, rounded, very narrow; suture distinct and deep; aperture trans- 
verse, narrow; peristome simple, acute; base convex; umbilical} 
region indented, umbilicus closed; greater diameter 4, lesser 3.5, 
height 3 mm. 
Hartland, Vermont, rare; a circumpolar species common to 
three continents. Sitka, Alaska; Lake Tahoe; San Gorgonio 
Pass, Riverside Co., Cal.; Nevada; Texas; Florida. 
13 Hvalina multidertata 
Devressed, thin, yellowish horn-color, smooth, shining, pellu- 
cid; whorls 6, slowly increasing, suture impressed; aperture trans- 
verse, narrow, lip extending to the perforated axis, base convex, 
