LYMN.ELLVE OF NORTH AMERICA. 89 



smooth forms usually referred to Melanopsis possess. That feature 

 also suggests the relationship of this shell to Stolidoma, but there is 

 no evidence that the axis of the spire has been absorbed, as is usually 

 the case with the Auriculidse. The character of the aperture also seems 

 to render its reference to any of the Bulimidae improper. 



"The collection contains a considerable number of small examples, 

 which I at first regarded as belonging to another species; but, after 

 comparing them with the apical portion of the form here described, 

 I am quite convinced that they are the young of this species and rep- 

 resent the apical portion of the adult shell" (White). 



This is a peculiar species, unlike any living or fossil form. It 

 approaches some forms of the emarginata group, especially Galba con- 

 tractu. The cylindrical whorls and narrow aperture are peculiar. It 

 is tentatively referred to the subgenus Stagnicola. 



The two small specimens figured by White (5, 6, plate XVI) seem 

 scarcely to belong to the same species, the sutures being much deeper 

 and the whorls consequently much rounder than in accelerata. A study 

 of additional material should be made to throw more light on the re- 

 lationship of these small specimens to accelerata. They may possibly 

 be immature specimens. 



CRETACEOUS LYMNAEAS. 



Galba nitidula (Meek). Plate XVI, figures 20-22. 



Melania? nitidula Meek, Proc. Acad. Nat. Sci. Phil., p. 314, 1860. 



Limncea nitidula Conrad, Eocene Smithsonian check-list, p. 9, 1866. — 

 Meek, Simpson's Rep. Great Basin, Utah, pp. 363, 373, pi. 5, fig. 14, 1876; Bull. 

 U. S. Geol. & Geog. Surv. Terr., Ill, p. 610, 1877.— Miller, Mes. and Csenoz. 

 Geol., p. 72, 1881; Journ. Cin. Soc. N. H., Ill, p. 82, 1880.— White, 3rd An. 

 Rep. U. S. Geol. Surv., p. 445, pi. 6, figs. 15-16, 1883; An. Rep. U. S. Geol. and 

 Geog. Surv. Terr., XII, pt. I, p. 84, 1884.— Boyle, Bull. U. S. Geol. Surv. no. 

 102, pp. 167, 168, 1893.— White, Bull. U. S. Geol. Surv., no. 128, pp. 45, 64, pi. 

 6, fig. 3, 1895 (nee. fig. 1-2).— Schuchert, Bull. U. S. Nat. Mus., 53, i, p. 356, 

 1905. 



Limncea (Limnophysa) nitidula Meek, U. S. Geol. Surv. 40th Parallel, 

 Vol. IV, p. 181, pi. 17, fig. 5, 1877.— White, An. Rep. U. S. Geol. and Geog. 

 Surv. Terr., XI, pp. 241, 243, 255, 1879.— Marcou, Proc. Nat. Mus., VIII, p. 330, 

 1885. 



Limnophysa nitidula White, Am. Journ. Sci. and Arts., ser. iii, XX, p. 45, 

 1880; An. Mag. N. H., ser. v, VI, p. 249, 1880. 



Limncea sp., White, Geol. Uinta Mts., p. 100, 1876. 



"Shell small, ovate-subfusiform ; spire conical, moderately ele- 

 vated; volutions about six and a half, convex, last one forming two- 

 thirds of the entire length; suture well denned; aperture subovate, 

 narrowly rounded below and angular above, scarcely equaling one-half 

 the length of the shell; columella apparently with only a very small 



