30 CONCHOLOGIA CESTRICA: 
tooth. It is impossible to distinguish it from some 
forms of //. ducculenta.’ The impossibility arises from 
the fact that it is, really, one of those forms. 
M. dentifera, BINN. 
Helix dentifera, Binn., Bost. Jour. 
Nat. Hist: 1, 1840; 
M, dentifera, 
[B. & B.] 
Shell depressed, spire sub-convex; 
base well rounded; whorls 5, fine stri- 
ate; aperture wide; lip broadly reflect- 
ed, and covering the umbilicus; parietal 
tooth prominent; color yellow horn. 
i, 1o, “We 23 mall: 
Station, mountain forests, Pennsyl- 
vania. 

M. palliata, Say. 
Helix palliata, Say, Jour. Phil. Acad. F. Ss 11, 182m: 
M. palliata, Shell depressed, brown, rough or hispid; 
Fig, 24, whorls 5, flattened above, striate; aperture 
three-lobed, contracted; lip reflected, white, 
often edged with brown, with two inter- 
marginal teeth; pillar lip with a long, 
white, curved, tooth, originating at the 
umbilicus, which is covered. H. 9, W. 
35, mill. 
Station, mountain forests. Western Pennsylvania. 

Sub-genus TRIODOPSIS, RAFINESQUE, I819Q. 
Shell orbiculate-depressed, or sub-globose ; obliquely 
striate; whorls 5-7, the last sub-deflected ; umbilicate, 
or closed; aperture sinuate, sub-triangular; peristome 
with a broad reflected margin; sides of the aperture, 
armed with strong teeth, 
