LYMN ID OF NORTH AMERICA. 97 
a lens; aperture subovate, rather narrowly rounded below, and acutely 
angular above; columella twisted into a moderately prominent fold. 
“Length, 0.39 inch; breadth, 0.19 inch; apical angle slightly con- 
vex, divergence about 38°” (Meek). 
Type: U. S. Nat. Mus., nos. 692, 694. 
Horizon: Bridger formation, Middle Eocene Period. 
Locatity: Ham’s Fork, north of Fort Bridger, Uinta County, 
southwestern Wyoming. 
ReMArRKS: “This variable form is so closely allied to the last that 
1 am nearly satisfied that it is only a variety of the same. Its chief 
difference consists in having the volutions of its spire a little more 
convex, and more drawn out, as it were, so as to give decidedly greater 
obliquity to the suture. It seems to be even more nearly allied to 
some of the more slender forms regarded by Mr. Binney as varieties 
of L. humilis of Say; though it is a decidedly more attenuated, less 
compact shell than that represented by Mr. Binney’s figure of L. hu- 
milis, given on page 63 of his ‘Land and Fresh-Water Shells,’ published 
by the Smithsonian Institution. There is scarcely any probability, 
however, that our shell is identical with any of the existing species” 
(Meek). 
Meek calls attention to the similarity between this species and 
vetusta; there is, however, considerable difference, not only in size, 
but in the general shape of the whorls. Its generic affinities seem to 
be with Stagnicola. 
There seems to be some discrepancy between the figures of this 
species in Simpson’s Utah report and in the Fortieth Parallel report. 
The latter agree better with the description, in some respects, than 
do the former, which fail to show the columella fold and deep sutures 
mentioned by Meek. The figures from both reports are shown on 
plate XVI. Figures 18-19 are the same as those used by White in 
Bulletin 128, U. S. Geol. Surv. (See ante, p. 91.) It is possible that 
these figures represent a third species. 
OLIGOCENE LYMNEAS. 
Galba diaphana (Evans & Shumard). Unfigured. 
Lymnea diaphana Evans & SHUMARD, Proc. Phil. Acad., p. 165, 1854.— 
Haynven, Proc. Phil. Acad., p. 158, 1857. 
Limnea diaphana M. & H., Proc. Phil. Acad., 1856, p. 278. 
Limnea diaphana Meex, Smithsonian Check List, p. 13, 1864.—BINNEY, 
L. & F. W. Sh. N. A., II, p. 72, 1865 —Wnuite, Bull. U. S. Geol. & Geog. Surv. 
Terr., III, p. 613, 1877—Muier, Journ. Cin. Soc. N. H., III, p. 272, 1880; 
Mes. & Cenoz. Geol., p. 174, 1881. 
