94 



PUPILLIDAE 



The Pupillidae live in all manner of habitats: in damp places 

 under loose bark, under sticks and other forest debris, in open 

 fields of grass, on limestone rocks in dry places along the margins 

 of streams, and sometimes on the hot and dry borders of railway 

 embankments. A few species may be found on the trunks of 

 standing trees, or on weeds and small plants in the woods. The 



Pupillidae feed on fresh vegetable matter, often on fungi and 

 even more often on decaying plant matter. They may be found 

 in winter under leaves and bark. The family is widely dis- 

 tributed throughout the world. It has many representatives in 

 North America. Illinois has over a score of species and races. 



Key to Genera 



1. Aperture with 1 or more denticulations or plaits, p. 96 2 



Aperture without denticulations, p. 109 3 



2. Peristome with a constriction or indentation near middle. . . 



Vertigo, p. 103 



Peristome without a constriction or indentation near middle. 

 Gastrocoptay p. 94» 



3. Aperture of shell with lip thickened and turned back or re- 



flected PupoideSy p. 108 



Aperture of shell without a thickened or reflected lip 



Columella, p. 109 



Genus GASTROCOPTA Wollaston, 



Snails belonging to the genus Gastrocopta represent an im- 

 portant and numerous branch of pupoid snails. The shells are 

 small, ranging from about three-sixteenths inch (4.5 mm.) to 

 less than one-sixteenth inch (1.5 mm.) in height. 



