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



Fig. 156. 



whirls, tlie last of which has a faintlj angular appearance near the suture. 

 Aperture narrow and elongated, two-thirds the length of tlie 

 shell, acute behind. Columella short, delicate, slightly sinu- 

 ate, folded. Length |, diara. ^ inch.' 



Sacramento River, California : Budd. 



A very well-marked species, of a porcelain-like structure 

 and color, which appears not to be the consequence merely of 

 blanching. It is less slender tlian Ph. hypnorum, and more 

 like Ph. gi/rina, Say, or Ph. rivalis, in form, but is a far more 

 delicate shell, and one of the most elongated species. ( Gould.) 

 Physa virfjinea, Gould, Proc. Boston S. N. H. II, 215 (1847) ; U. S. Ex. 



Ex. Moll. p. 120, f. 138, 138a (1852) ; Otia, 43. 



* 



Fig. 156 is drawn from a specimen lent me by Dr. Gould. 

 Specimens have recently been added to the collection of the 

 Smithsonian. 



Fig. 157. 



Pliysa liunierosa, Gopld. — Shell subrhomboid, solid, smooth and 



white ; spire acute ; whirls five, tabulated ; aperture equalling one-half 



to two-thirds tbe shell's length, rounded posteriorly ; labrum expanded ; 



columella scarcely plicate, callus hardly perforated. Length 



2 to -j'jy, breadth | inch. 



Found by Dr. Thomas H. Webb and by W. P. Blake, in the 

 Colorado Desert and at Pecos River. 



The broadly tabulated whirls, with the acute, elevated spire, 

 and foldless columella clearly distinguish this species. It is 

 like P. tahulata, Gould, and the variety figured by Haldeman, 

 as P. ancillaria (fig. 7), which he regards as a monstrosity; 

 the deep suture and simple columella distinguish it from that 

 species. {Gould.) 



Phijsa humerom, Gocld, Proc. Bost. Soc. Nat. Hist.' V, 128 (1855) ; Otia, 

 216 ; Pac. R. R. Rep. V, 331, pi. xi, f. 1-5 ; Prelim. Rep. 23 (1855). 



It has also been found at San Diego. The shell figured was 

 presented by Dr. Gould to the Philadelphia Academy. 



