102 THE CHICAGO ACADEMY OF SCIENCES. 
MIDDLE MIOCENE LYMNAEAS. 
Lymnza stearnsi Hannibal, Ms. Plate XVII, figure 11. 
Limnea maxima STEARNS, Science, N. S., XX, p. 154, 1902; Univ. Cal. 
Pub., Geology, V, p. 70, fig. 1, 1906. (Not Limnea stagnalis var maxima CoL- 
tin, Ann. Soc. Mal. Belg., VII, p. 94, 1872.) 
“Partly exposed in portions of a fine compressed sediment of 
lacustrine origin are several casts of a very large Limnea, suggestive 
in a general way of the circumboreal stagnalis, but so much distorted 
as to preclude a more definite description.” (Stearns. ) 
‘Type: Uni. (Cals, Coll Invert; no. 10002. 
Horizon: Mascall beds, Middle Miocene Period. 
Locatity: Three-quarters of a mile east of Belshaw’s ranch, 
Grant County, John Day Valley, Oregon. 
REMARKS: The known specimens of stearnsi are so imperfect 
as to preclude an accurate discussion of the relationship of the species. 
Apparently it was a species similar to the recent stagnalis, judging by 
the size and form of the casts, and there is good reason to believe that 
it is a representative of the early Asiatic invasion and, hence, an an- 
cestor of the recent Lymne@a stagnalis. More material is highly de- 
sirable, especially those showing the external character of the shell. 
Of the known fossil Lymneas, stearnsi is the nearest approach to the 
typical genus, containing the circumboreal stagnalis. 
PLIOCENE LYMN EAS. 
Polyrhytis kingii (Meek). Plate XVII, figures 1, 2. 
Limnea (Polyrhytis) kingii Meex, U. S. Geol. Surv. Terr., IX, p. 532, 
1876; U. S. Geol. Surv. 40th Parallel, IV, p. 192, figs. 6,7, 1877——WuirtE, Bull. 
U. S. Geol. & Geog. Surv., III, p. 614, 1877-——Marcou, Proc. Nat. Mus., VIII, 
p. 340, 1885—ScHucHERT, Bull. U. S. Nat. Mus., 53, 1, p. 356, 1905. 
Limnea kingi, Miter, Journ. Cin. Soc. Nat. H., IV, p. 121, 1881—Wzuire, 
3rd An. Rep. U.S. Geol. Surv., p. 446, pl. 32, figs. 30-31, 1883—Tryon, Struct. 
and Syst. Conch., III, p. 101, 1884—Baker, Science, n. s., XXVII, p. 948, 1908. 
Lymnea, sp., Kinc, U. S. Geol. Surv. 40th Parallel, I, p. 436, 1878. 
“SHELL: Ovate; spire short; volutions about four, convex, rap- 
idly increasing in size, last one very large and ventricose; suture well 
defined; aperture large, subovate; columella apparently with a mod- 
erately well-developed fold; surface ornamented by regular, distinct 
vrtical cost, that are strongly defined on the body-volution, but more 
obscure or nearly obsolete on the spire. 
“Length, 0.73 inch; breadth, about 0.43 inch.” (Meek.) 
Tyre: U.S. Nat. Mus., no. 8097 (Holotype). 
