148 



bleached. Than A. depressa, nob., (changed to paludosa, nob., 

 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. 



Valvata 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. 



Greatest breadth, less than one-fifth of an inch. InTiabits 

 Mexico. 



Differs from V. 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 V. 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 attenuatus. — Shell elongate tuiTeted, 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. Inhabits 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 



