40 LAND AND FRKSH- WATER SHELLS OF X. A. [PART IL 



rejiexa, umhrosa, and elodes of Saj, wliicli form apparently but 

 one species, are scarcely distinguishable from this variable shell 



Mr. Say's type of Liransea umbroi^a is still preserved in the 

 Philadelphia Academy. My Figure 49 is a fac-simile of the 

 outline of one of his, and a copy of his description here follows. 

 The name umbrosa was substituted by Mr. Say for the pre- 

 occupied elongatus. The shell is considered distinct by Halde- 

 mau and DeKay, doubtfully so in Adams' Shells of Yermont. 



Limneus elongatus. — Shell horn-color, tinged with reddish-hrown ; spire 



elongated, tapering, acute ; whirls six or seven, slightly convex, wrinkled 



across ; body whirl, measured at the back, more than lialf 



Fig. 49. *^^® total length ; suture moderately indented ; aperture less 



than half the length of the shell ; labium with calcareous 



deposit. Length one and three-tenths inch. 



Inhabits, in considerable numbers, the ponds and tranquil 



waters of the upper Missouri. It is very distinct from L. 



catascopium, by the much greater proportional length of the 



spire. (Say in J. A. N. S.). Rainy Lake and Seine River 



f Upper Canada. 



I am under the necessity of changing the name which I 

 first applied to this shell, that of elojigatus being pre-occupied 

 by Draparnaud for a very diflerent species. The fold of the 

 columella is much less profound than that of L. palustris, Liu., 

 which it much resembles. {Say in Am. Conch.) 



Liransea pleheia, Gould, is quoted doubtfully as a synonym of 

 L. umhrosus, by Adams (Middlebury Shells, and Sill. Journ. 

 [i], XL, 268). I refer it, however, to L. palustris, as that 

 species is xound in Massachusetts, while umbrosa is not. Gould 

 mentions pleheia by name only in the Catalogue of Massachusetts 

 Shells. 



My opinion of the identity of Limnsea exilis with L. rejiexa 

 is based upon an examination of Mr. Lea's original specimen. 

 His description and figure here follow. Haldeman and DeKay 

 place exilis in the synonymy of rejiexa. 



Limnaea exilis. — Shell attenuated, very thin, longitudinally striate; 

 whirls seven, plano-convex, columella reflected ; aperture ovate-oblong. 



Ohio. My cabinet. Diam. .4, length 1.5 incli. 



This is, perhaps, the most attenuated Limnsea yet observed in this 

 country. It approaches most to the rejlexus, Say, but is more elongate 

 than that species. The most remarkable character of the exilis is, por- 



