306 AMERICAN JOURNAL 



MONOGRAPH OP THE TERRESTRIAL MOLLTJSCA OP 

 THE UNITED STATES. 



BY GEORGE W. TRYON", JR. 



[Continued from p. 277.] 



Family HELICID^. 



Shell depressed, or globoselj 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. 



Sid)families. 



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

 times expanded, more or less thickened within the margin. 



Mesodontinje. — Shell frequently toothed, lip broadly re- 

 flected and appressed. 



HYGROMIIN^. 



Genera. 

 * Umhilicate. 



1. Hygromia, Risso. 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 Rocky 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. 



