248 THE CHICAGO ACADEMY OF SCIENCES. 
one’s hand. In progression it is very rapid, probably exceed- 
ing, in comparison with its size, all other species in the rapidity 
with which it crawls. It seems to be confined to the northern 
and southern regions. 
FAMILY VALLONIIDA* 
For general characters of the family, see the description 
of the genus Vallonia, below. 
Genus VALLONIA Risso, 1826. 
Shell: ‘Minute, openly and widely umbilicate, depressed, 
the spire low-convex, consisting of 3 to 4% whorls, color light 
and uniform; surface smooth or ribbed; periphery rounded; 
last whorl usually descending infront. Aperture oblique, circu- 
lar or short-oval; peristome continuous or nearly so, expanded 
or reflexed, often thickened within.” (Pilsbry.) 
Fig. 76. 
Genitalia of VALLONIA PULCHELLA Miiller. (Pilsbry, Guide to Heli- 
ces, pl. Ixili, Fig. 9.) 
Animal: ‘Foot small, short, with no pedal grooves; edges 
of sole somewhat crenulated; sole undivided; eye-peduncles 
cylindrical, not enlarged distally; tentacles short; labial lobes 
well developed. Genitalia (Fig. 76) having the penis short, 
‘with terminal retractor; epiphallus short, bearing a flagellum. 
Dart sack present, single, containing a straight, bladeless dart. 
No mucus glands. Duct of spermatheca long, branchless.” 
(Pilsbry). For jaw and radula see V. pulchella. 
Distribution: ‘North America south to Texas; Japan and 
middle China to Europe and Atlantic Islands.” (Pilsbry.) 
Found fossil in the Eocene and Miocene. 
*The position‘of this family, as well as that of Cochlicopide, is very uncertain, and it is 
placed here provisionaily. 
