18 



titute of elevated revolving lines. The young shell is carinated. 

 I am indebted to. Mr. Lesueur for a specimen. 



M. obovata. Shell subobovate, dark brown or blackish; volu- 

 tions nearly five: spire remarkably rounded, short: body zchirl 

 with a very obtuse, slightly indented band or undulation a 

 little above the middle: aperture more than twice the length 

 of the spire, narrow: labium polished, with a callous above: 

 labrum not projecting near the base, subrectilinear from the 

 shoulder to the basal curve, very convex at the shoulder; base 

 rounded and without indentation. 



Animal, foot rounded, or rather longer than wide, equally 

 rounded before and behind; above yellowish-white, lineated 

 with black lines. 



Inhabits Kentucky River, and some other tributaries of the 

 Ohio. Length, three-fourths; breadth, nearly half an inch. 

 Var. a. Indented band almost obsolete. 



The spire, and even a part of the body whirl in old shells, 

 are sometimes remarkably eroded, as in the M. (anculotus) 

 prcerosa. Nob., and, indeed, the general appearance is such, 

 that at a little distance, and without particular observation, it 

 might be readily mistaken for that shell; but the form is less 

 globular and the aperture is altogether different. I found it 

 very abundant in Kentucky River in company with that shell 

 and other species of Melania. I also observed it at the Falls of 

 the Ohio. Lesueur and Troost obtained specimens in Fox 

 River of the Wabash. When young, the undulation is hardly- 

 visible, and the shell is often of a dull yellowish color, which 

 on the larger volutions becomes gradually of the characteristic 

 color. 



M. integral Subglobose, horn color; volutions rather more 

 than three, rounded, obsoletely wrinkled: spire very short, less 

 than half the length of the aperture: suture rather deeply im- 

 pressed: body whirl large: aperture dilated, ovate, acute above: 

 columella flattened, polished: labrum regularly rounded: base 

 regularly rounded, without any undulations or sinus: umbilicus 

 none: operculum obviously spiral. 



Length, nearly one-fifth of an inch. 



Animal, foot longer than wide, rounded behind; with ! 

 anterior angles a little excurved: eyes black, conspicuous; 

 tentacula rather long and slender. 



Inhabits Ohio River and many of its tributaries. 



This is a \cry common little shell, abounding more in many 



