208 THE CHICAGO ACADEMY OF SCIENCES. 
Genitalia: See generic description. 
Distribution: Eastern and Central United States, and Can- 
ada; west to Minnesota. 
Geological distribution: Pleistocene of the Mississippi Val- 
ley; Loess. 
Habitat: Very abundant under logs, underbrush, and in 
crevices or under loose bark. Sometimes found buried in the 
earth. Dry situations are not favorable to it, and it prefers 
moist localities in wooded districts. 
Remarks: This is our most abundant species, and, unlike 
most of our Helices, is gregarious, being generally found in 
colonies of from twenty to a hundred or more. Theanimal is 
sluggish in its movements, but is not at all shy, allowing itself 
to be picked up and examined without withdrawing into its 
shell. Its locomotion is slow and careful. The species is very 
variable in the height of its spire, some specimens having an 
elevated, convex spire, while others are perfectly flat. This 
variation is ina great measure due to the habit of crowding 
itself into narrow crevices, which causes the shell to assume a 
flat-whorled aspect. The convex forms are generally found, 
in wide, open crevices or under logs, while the flat-whorled 
forms are found in small, narrow crevices or under loose bark. 
The albino form is found very sparingly. The measurements 
and figures show well the variation in the spire. The striation 
of the species varies from almost smooth (/ergusont) to very 
coarsely ribbed (mordax). It is fond of climbing trees and is 
often found at a-considerable height from the ground. 
Egg laying begins about the first week in June and the an- 
imals are then in their best condition. From twenty to eighty 
pure white, opaque eggs are laid, agglutinated together in soft 
clay (Fig. 22). About thirty days are required for them to 
hatch, and about the middle of July young snails are found 
with two perfect whorls. The eggs measure 2.75 mill. in diam- 
eter and when dry become hard and brittle. 
80. Pyramidula solitaria Say, pl. xxix, fig. 1. 
Felix solitaria SAY, Journ. Phil. Acad., Vol. II, p. 157, 1821. 
Pyramidula occidentalis VON MARTENS. 
Pyramidula solitaria limitaris DAWSON, L. and F. W. Moll. coll. Sum- 
mers, 1873, 1874, pp. 347-350, 1875. 
Patula solitaria albina W. G. BINNEY. 
Shell: Depressed-globose, rather solid, diaphanous, deeply 
and widely umbilicated; surface slightly shining, covered with 
coarse, crowded, oblique striz; color dark horn, with two re- 
