64 HELICIDyE. 



" Succinea vermeta. Shell sub-oval, yellowish, very thin and 

 fragile, somewhat diaphanous, with nearly three very oblique 

 volutions ; whorls very much rounded, wrinkled ; suture 

 very profoundly impressed ; spire rather prominent and 

 acute ; aperture ovate, the superior termination rounded. 



"Succinea undulata. Shell sub-oval, pale yellowish, translucent, 

 fragile ; volutions three and a half. Spire moderate, obso- 

 lete ; body whorl wrinkled, or rather slightly undulated. 

 Columella narrowed, so as to exhibit the appearance of an 

 interior umbilicus. Length half an inch." 



Considerable confusion prevails in the use of the 

 names of these species, and we attempt to reconcile 

 the differences in the following manner. 



Succinea campestris, Say, is an exclusively southern 

 species. The shell commonly mistaken for it is the 

 species which Mr. Say called ovalis, and which most 

 resembles it. Consequently the occurrence of Suc- 

 cinea campestris, Say, in the works of Messrs. Gould, 

 Mighels, and Sager is erroneous. We confine the use 

 of that name to the southern species. 



Succinea ovalis, Say. This species, diffused universally 

 in the middle and northern States of the Union, is 

 that which is described in the works of Messrs. Gould, 

 Mighels, Kirtland, and Sager, as Succinea campestris, 

 Say. It varies much in size, and in the divergence 

 of the last whorl from the axis of the shell, and this 

 last variation when strongly developed constitutes Suc- 

 cinea obliqua, Say. Succinea ovalis of Messrs. Gould, 

 Adams, Mighels, and Sager is not the ovalis of Say, 



