23 



Differs from V. sincera, Nob., of the North-west Territory, 

 in being more depressed, and in having a shoulder or plane 

 surface near the suture. The umbilicus is larger than that of 

 the V. piscinalis, Mull., and the spire more depressed; that spe- 

 cies is also destitute of the depressed shoulder. 



LYMNEUS, Lam. 



L. capcralus. Shell suboval, a little oblong, obscurely yellow- 

 ish 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: suturt not 

 very deeply impressed: aperture rather dilated; fold of th 

 bium not profound. 



Inhabits Indiana. 



The remarkable character of this species consists in the 

 numerous revolving lines with which the surface is marked; 

 hut these are so minute as to require the aid of a magnitierto 

 bring them to view. It was found on land subject to inunda- 

 tion, near New Harmony, by Dr. Troost. 



L. atti nuatus. Shell elongate turretcd, somewhat translucent: 

 spire slender, attenuated, acute: whirls six or seven, with but a 

 very slight convexity; wrinkles more distinct towards the 

 aperture: body whirl 9 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. reft xus, Nob., 

 than to any other known species of North America; but it is 

 only necessary to compare the two in order to perceive a wide 

 dillercnce between them. The present is smaller and propor- 

 tionally more slender, and the spire is more attenuated. 



SUCCINEA, Dual 



S. verrneta. Shell suboval, yellowish, very thin and fragile, 

 somewhat diaphanous, with Dearly three verj oblique volu- 

 tions: whirls very much rounded, wrinkled: suture ven pro- 



