OF CONCHOLOGY. 223 



DECRIPTIONS OF NEW SPECIES OF NORTH 

 AMERICAN LIMNiEID^. 



BY GEORGE W. TRYON, JR. 

 PHYSA. 



Until last year, very few American species of this genus 

 were known, or rather none of our couchologists had investi- 

 gated with sufl&cient care their specific characters ; consequent- 

 ly, a number of distinct forms have long existed in our cabi- 

 nets, under the name of Physa heterostropha. The specific, 

 characters in the Physse, though not very marked, are really 

 very constant, and, therefore, probably not only most of those 

 species recently described by Mr. Lea,* and those herein de- 

 scribed, will stand, but we may reasonably conclude that many 

 yet uncharacterized species inhabit our waters. 



1. Physa propinqua, Tryon. — t. 23, f. 5. 



Description. — Shell large, fragile, inflated; spire short, apex 

 acute; body whorl almost shouldered, very large, covered 

 with distinctly elevated lines of growth on the adult speci- 

 mens; the surface frequently exhibits several planes, instead 

 of being uniformly rounded; aperture large, oval, outer lip 

 regularly rounded; columella a little twisted. 



Dimensions. — Length 19 millimetres, diameter 13 mill. 



HaUtat. — Jordan Creek, S. W. Idaho. W. M Gabb. 



My Cabinet. Cabinet of Mr. Gabb. 



Observations. — This species has a shorter spire, its sutures 

 are not well impressed, it has fewer whorls, is more ventricose, 

 .more solid, and is a smaller shell than Ph. ampullacea [hul- 

 lata) Gould. Pli. Lordi, Baird, is still more ventricosely in- 

 flated, and the columella is not twisted. Ph. Traskii, Lea, is 

 a longer, more cylindrical species. 



Mr. Gabb sent me nine specimens, of which several are 

 adult. 



* Proc. Acad. Nat. Sci., 1864. 



