306 AMERICAN JOURNAL 



MONOGRAPH OF THE TERRESTRIAL MOLLUSC A OE 

 THE UNITED STATES. 



BY GEORGE W. TRYON, JR. 



[Continued from p. 277.] 



Family HELICIDjE. 



Shell depressed, or globosely elevated, strong, striate, with 

 the epidermis colored, frequently banded, opaque, lip either 

 margined within, or expanded, or appressed and reflected. 

 Aperture sometimes toothed. 



Animal snail-like, not so narrowly lengthened generally as 

 in Helicellidse. Buccal plate arcuate, thick, with transverse 

 rounded ribs. 



Lingual dentition. — Uncini and laterals the same in form, 

 the former 1-2 dentate or notched irregularly, the latter 1 

 dentate. 



Subfamilies. 



Hygromiin^e. — Shell not toothed, lip not reflected, some- 

 times expanded, more or less thickened within the margin. 



Mesodontin^e. — Shell frequently toothed, lip broadly re- 

 flected and appressed. 



HYGROMIIN^E. 



Genera. 

 * Umbilicate. 



1. Hygromia, Eisso. Globosely depressed, not angulated, 



generally hirsute; whorls 5-7, convex; aperture round- 

 ed or widely lunate; lip acute, slightly expanded and 

 thickened within. Corneous, generally unicolored. 

 Size small. 



Inhabits east of Kocky Mountains. 



2. Aglaja, Albers. Depressed-conoidal, sometimes ob- 



scurely angulate; lip thickened within, encroaching a 

 little on the umbilicus. Yellowish-brown, almost al- 

 ways banded. Size large ; surface malleate. 



Inhabits California and Oregon. 



