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bleaclied. Than A. depressa, noh., (changed to paludosa, noh., 
as the name is preoccupied^) it has a more elevated and acute 
spire, larger umbilicus and more regularly rounded body whirl. I 
am unacquainted with the A. linearis^ Perry, which he supposes 
to be a native of the coast of North America. 
Yalvata humeralis. — Shell subglobose, depressed: spire 
convex, not prominent : whirls three and a half, with the shoulder 
depressed, plane ; wrinkled across, or rather with slightly raised 
lines : aperture appressed to the penultimate whirl, but not inter- 
rupted by it ; umbilicus rather large. 
(Q-reatest breadth, less than one-fifth of an inch. Inhabits 
Mexico. 
Differs from Y. sincera, nob., of the North-west Territory, in 
being more depressed, and in having a shoulder or plain surface 
near the suture. The umbilicus is larger than that of the Y. pisci- 
nalis, Mull., and the spire more depressed ; that species is also des- 
titute of the depressed shoulder. 
Lymneus caperatus. — Shell suboval, a little oblong, obscurely 
yellowish horn color : spire half the length of the mouth : apex 
acute : whirls slightly wrinkled across, and with very numerous, 
equal, subequidistant, elevated, minute, revolving lines : suture not 
very deeply impressed : aperture rather dilated; fold of the labium 
not profound. 
Inhabits Indiana. 
The remarkable character of this species consists in the numer- 
ous revolving lines with which the surface is marked ; but these 
are so minute as to require the aid of a magnifier to bring them to 
view. It was found on land subject to inundation, near New Har- 
mony, by Dr. Troost. 
Lymneus attenuates. — Shell elongate turreted, somewhat 
translucent : spire slender, attenuated, acute : whirls six' or seven, 
with but a very slight convexity ; wrinkles more distinct towards 
the aperture : body whirl, measured at the back obviously less than 
half the total length. 
Length, one inch. Inliabits Mexico. 
This species abounds in the ditches and ponds in the vicinity of 
the Capitol, It is more nearly related to L. reflexus, nob., than to 
any other known species of North America ; but it is only neces- 
sary to compare the two in order to perceive a wide difference 
