9G 



Descriptions of New Fluviatile Shells 



much elevated ; whorls 12, very strongly striated and ribbed, 

 particularly the upper ones; the ribs extend only to a promi- 

 nent, acute carina on each whorl, situated below the middle, 

 between which and the suture below, one or two coarse stride 

 alone are visible ; sutures deeply impressed ; aperture very 

 small, ovate, purplish within; columella regularly curved, 

 without indentation, and with but a small, very narrow sinus 

 at base. 



Length 1 inch (26 millim.). Diam. 0.28 inch (7 millim.). 

 Length of aperture 0.22 inch (5i millim.). 

 Breadth of do. 0.15 inch (4 millim.). 



Habitat— A small stream emptying into the Tennessee river, 

 near Loudon, Tennessee. 



Cab. Lye. Nat. Hist., K Y. J. G. Anthony. B. W. Budd. 



Obs.— This is one of the slenderest and most elevated of the 

 genus ; more than forty specimens are before me, and they are 

 very constant in all their characters ; it comes nearest to M. 

 striatula Lea by its folds and strias, but should not be confounded 

 with it, being different in every other particular ; the number 

 of whorls is greater by one half, the striatula having only eight; 

 its proportions are altogether more slender, the striatula stand- 

 ing as 21 to 49, while this is 28 to 100. The present species is 

 also much more folded and rough than the striatula, which is 

 essentially a striate shell. Upon the older specimens the folds 

 are nearly obsolete on the two lower whorls, being there coarsely 

 striate only. About twelve strice on the body whorl and six on 

 the penultimate ; more elevated in the centre, which renders 

 these whorls sub-angulated ; lines of growth strong, by reason 

 of which the two last whorls have quite a varicose appear- 

 ance. 



