34 LAND AXD FRESII-WATER SHELLS OF N. A. [PART IV. 



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 lliver of the Wabash. "When young, the undula- 

 tion is hardly visible, and the shell is oiten of a dull yellowish color, 

 which on the larger volutions becomes gradually of the characteristic 

 color. — Say. 



Melania Ilikh'etJiiana, Lea, is tlie half grown stage of this 

 species, as I have verified, by an examination of Mr. Lea's 

 original specimens, one of which he kindly presented to me 

 (see figure). In uniting it with obovata, it is proper to say 

 that Prof. Haldeman and Dr. Jay have preceded me. 



The following is Mr. Lea's description of 



Melania Hildretliiana. — Shell smooth, fusiform, rather thick, horn- 

 color; spire short, pointed at the apex; sutures deeply impressed; 

 whorls Ave, convex; aperture large, angular at base, 

 ovate, white or purple. 

 Habitat. — Ohio lliver, near Marietta; Dr. Hildreth. 

 Diameter, -25 ; length, -37 of an inch. 

 Observations. — The aperture of this little species is 

 nearly two-thirds the length of the shell. In outline it 

 is allied to M. fnsiformis, herein described. It may be distinguished 

 by the sutures being more impressed, and the base being more an- 

 gular. One of the specimens is purple on the columella and at the 

 base. I dedicate it to Dr. Hildreth, to whose kindness I owe several 

 specimens. — Lea. 



This is nothing more than a small variety of L. obovata, Say. 

 I have not seen many specimens, but they all appear to be of 

 stunted growth, and I should not be surprised if future research 

 proves them to be living in circumstances unsuited to their full 

 development. 



The following description is of a not entirely full grown 

 shell, retaining the spire complete to the apex. It is a rare 

 state, several whorls being general]}^ lost by truncation. 



The remarkably shouldered whorls and smaller size ^'^' "''• 

 of M. undosa will scarcely distinguish it as a variety of 

 this species. Its description here follows : — 



Melania Mndosa. — Shell ovate, smooth, olivaceous, moder- 

 ately thick; whorls C-7, rapidly converging to the apex, 

 convex ; body-whorl ample, with a distinct, but somewhat rounded 



