190 THE CHICAGO ACADEMY OF SCIENCES. 
pore placed on the upper surface of the extremity of the foot; 
pedal grooves distinct. 
Faw. Similar in shape to that of Vitrea indentata, with a 
broad, inconspicuous median projection (see Fig. 38). 
Radula formula: %+414+3+4+3+4+ (12—1—12); teeth 
similar in form to those of arboreus, excepting that they are a 
little wider; the fourth lateral is modified, There are over 50 
rows of teeth. 
Distribution: ‘Ontario to Florida, west to Montana, Ari- 
zona and New Mexico, Bermuda.” (Pilsbry.) West Indies, 
Japan. (Binney.) Manitoba. (Hanham.) 
Geological distribution: Pleistocene; Loess. 
Habitat: Yound in and about rotting logs in damp woods. 
Remarks: A common species, distinguished by its small 
size, flattened spire and very wide umbilicus. The animal is 
very timid in captivity, hesitating a long time before starting 
to crawl over the surface upon which it has been placed. Like 
the Vitreas which itsomewhat resembles, this little species is 
widely distributed, and will ultimately be found to be as com- 
mon as Z. arboreus, when all parts of the area are thoroughly 
explored. 
Genus GASTRODONTA Albers. 
Gastrodonta ALBERS, Die Helicien, p. 88; Malak. Blatter, Vol. IV, p. 
91, 1857. 
Ventridens BINNEY & BLAND, Land and Fr. Wat. Shells, N.A., Part I, 
p. 292, 1869, 
Shell; Usually umbilicated, rather thin; horn-colored, 
glassy, covered with coarse strie#; whorls five to seven; aper- 
ture lunate, exhibiting two modifications: (1) with teeth or lam- 
inz on the base (gularis Say); (2) with a strong white callus 
on the floor of the last whorl (4gera Say); peristome simple, 
acute. 
Animal: Generally blackish; head, neck and eye-pedun- 
cles much darker, the latter very long; mucus pore a longi- 
tudinal furrow, situated on the upper surface of the extremity 
of the foot, and opened and closed at will. Locomotive disk 
furrowed above the margin of the foot. Genitalia provided 
with a dart sac, in which is contained a long, curved, calcareous 
dart upon the vagina.* 
*Pilsbry, Proc. Phil. Acad., 1894, p. 16. 
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