458 THE CHICAGO ACADEMY OF SCIENCES. 



the twisted type of Galba than of the gyrate, type of Lymnaa, and the 

 whole shell suggests the emarginata group of the genus Galba. 



Subgenus POLYRHYTIS Meek, 1876. 



1876. Polyrhytis MEEK, Rep. U. S. Geol. Surv. Terr., IX, p. 532. (Limnaa 



kingii Meek.) 



1877. Polyrhytis MEEK, Exp. 40th Parallel, Pal., pp. 192, 193. 

 1844. Polyrhytis TRYON, S. and S. Conch., Ill, p. 101. 



1905. Polyrhytis DALL, Mollusks of Alaska, p. 64. 



1908. Polyrhytis BAKER, Science, N. S. XXVII, No. 703, p. 943. 



SHELL : With well-marked longitudinal folds or ribs ; spire broad- 

 ly acute, generally shorter than aperture; axis twisted; columella lip 

 broadly expanded, obscuring the fold more or less; umbilical chink 

 well marked. 



ANIMAL, JAW, RADULA and GENITALIA: Unknown. 



DISTRIBUTION : Pliocene to recent fauna. 



Meek's Polyrhytis would seem to be a well marked division of 

 the Lymnseids, characterized by a longitudinally ribbed, ventricose 

 shell. Call's Lymn&a utahensis answers well to the diagnosis of Poly- 

 rhytis and is accordingly placed here. As remarked by Meek (Exp. 

 40th Parallel Pal., p. 193) Polyrhytis bears somewhat the same re- 

 lation to Lymncea that Costella Dall bears to Physa. No other recent 

 Lymncea at all resembles utahensis in the possession of this peculiar 

 sculpture which is probably produced by the unfavorable character of 

 their habitat, as remarked by Call. 



Polyrhytis is placed tentatively near Stagnicola. The genitalia 

 and radula of utahensis are unknown and until these are published the 

 group cannot be definitely placed. 



Galba utahensis (Call). Plate XXII, figures 9-11; plate 

 XXIV, figures 22-27. 



Radix ampla var. utahensis CALL, Bull. U. S. Geol. Surv., II, pp. 373, 379, 

 381; p. 401, pi. 6, figs. 7-9, 1884. KEEP, West American Sh.,,pp. 149, 314, 1904. 



Radix utahensis CALL, Proc. Davenport Acad. Sci., V, p. 5, pi. 1, figs. 7-9, 

 1886. 



Limnaa ampla var. utahensis STEARNS, Proc. Nat. Mus., XXIV, p. 291, 1901. 



fLimn&a catascopium INGERSOLL, Proc. Daven. Acad. Sci., II, p. 132, 1877. 



Radix ampla GILBERT, Mon. U. S. Geol. Surv., I, p. 298, 1890. 



Lymnaa utahensis STERKI, Nautilus, XXII, p. 142, 1909. 



SHELL : "Globose, somewhat umbilicated, irregularly costate, light 

 horn color, nearly pellucid ; spire rather small, conical ; whorls four to 

 four and one-half, convex, rather flattened above, giving rather a 



