50 



LAND AND FRESH- WATER SHELLS OF N. A. [PART II. 



Fitr 



Fig. 71. 



Limnxa acuta, Lea. — Shell elevated, turreted, thin, smooth, dark-brown ; 

 spire attenuate ; whirls six, aperture subovate. 



Pond four miles north of Philadelphia. Diam. .3, length .7 

 inch. 



This delicate species, though attenuate, is not so much so as 

 the exilis, herein described. Its whirls are more convex and 

 the body whirl larger, the aperture being about one-half the 

 length of the shell. Several specimens were found by me, some 

 years since, in a very small pond near the Falls of Schuylkill. 

 Since then this pond has occasionally dried up, and I have not 

 been able to find others. Although there are otlier ponds near 

 to this, which other species inhabit, I have never been able to discover 

 the acuta in any other spot. (Lea.) 



Limnseij. pkiladelphica, Lea. — Shell ovately-conical, thin, striated, shin- 

 ing, diaphanous, rather golden, imperforate; spire rather elevated ; sutures 

 much impressed, whirls five, convex ; aperture narrow-elliptical. 

 Hab. River Schuylkill, near Philadelphia. My cabinet and 

 cabinets of P. H. Nicklin, and Dr. Griffith. Diam. .20, length 

 .48 of an inch. 



This species is about the size of, and is allied to plica and 

 griffithianu, herein described, and to modicella, Say. It has a 

 more elongated aperture than yriffithiana, has a smaller fold 

 than plica, and is higher in the spire than modicella. The aper- 

 ture is about half the length of the shell. I procured many 

 specimens west of Philadelphia. Dr. Griflith informs me that he found 

 them south of the city. (Zea.) 



Limnsea fusiformis, Lea. — Shell fusiform, rather thick, closely striate, 

 pale yellow, imperforate ; spire rather short ; sutures slightly impressed ; 

 whirls six, flattened ; aperture narrow-elliptical. 



Hab. Niagara River, Lewistown, New York : Tobias Wagner. 

 My cabinet, and cabinets of P. H. Nicklin, and Tobias Wagner. 

 Diam. .35, length .60 of an inch. 



Among a number of interesting shells collected by T. Wagner, 

 during a long journey in the interior of our country, were several 

 specimens of this species, which has not been, I believe, before 

 noticed. It is found with, and is somewhat.allied to, L. desidiosa, 

 Say. It differs in being more fusiform, having a larger aperture, 

 and flatter whirls, and in being imperforate. It is about the size of, and 

 resembles, L. casta, herein described. It differs in being less elevated in 

 the spire, in the whirls being more flattened, in having a distinct and 

 curved fold, and in being imperforate. The aperture is nearly two-thirds 

 the length of the shell. The last two whirls are disposed to be wrinkled. 

 (Lea.) 



