LYMN/EIDA OF NORTH AMERICA. 9] 
accompanied by a label in Mr. Meek’s handwriting, referring them to 
this species. The examples figured by Mr. Meek in volume IV of the 
report of the United States Geological Exploration of the Fortieth 
Parallel, and copied by me in the Third Annual Report of the United 
States Geological Survey, are unlike these specimens, and unlike any 
form known to me in the Bear River fauna, and they do not answer 
to Mr. Meek’s description.” 
White’s reference of the species to Charydrobia stachei is quite 
erroneous, as he correctly states on page 58 of the same work, The 
resemblance of the two species is scarcely superficial. A careful study 
of all the figures of nitidula seems to point to the conclusion that Dr. 
White was in error in referring figures 1 and 2 on plate VI to nitidula. 
These figures seem to be the same as those used for Lymnea similis 
by White in the Third Annual Report, plate 29, figures 20, 21. 
Referring to the literature, we find that Meek’s figure of the 
species in Simpson’s Utah Report (pl. 5, fig. 14) agrees perfectly with 
his description. The next published figures are in the Fortieth Parallel 
Report, IV, pl. 1%, figs. 5, 5a. These certainly agree with both the 
original figure and description of Meek. White refigures these in the 
Third Annual Report of the Geological Survey, pl. 6, figs. 15, 16. In 
Bull. 128, Dr. White figures what are said to be copies of Mr. Meek’s 
unpublished figures (figs. 1, 2) and also a view of one of the type 
specimens (fig. 3). This last figure corresponds in every way with 
Meek’s figures in the Fortieth Parallel Report, but does not at all agree 
with figures 1 and 2 of White’s paper, nor do these figures answer to 
the description of Meek. It is also a curious fact that Meek’s un- 
published figures as published by White are an exact duplication of 
the figures of Lymnea similis Meek as figured in the Third Annual 
Report, pl. 29, figs. 20, 21. It would appear that some error had been 
made by Meek in labeling his unpublished figures, which certainly do 
not represent his nitidula as described and figured. 
Pleurolimnza tenuicosta (Meek and Hayden). Plate XVI, 
figures 9-11; Plate XVII, figure 4. 
Limnea tenuicosta MeEK and HaybdeEN, Proc. Phil. Acad., p. 119, 1856; 
Amer. Jour. Sci., ii, XXII, p. 428, 1856.—Mitrr, Jour. Cin. Soc. N. H., III, p. 
21, 1880; Mes. and Caen. Geol., p. 57, 1881. 
Limnea tenuicosta MEEK and HaybeNn, Proc. Phil. Acad., Pp. 278, 1856. 
Limnea (Acella) tenuicostata MreK and Hayven, Proc. Phil. Acad., p. 
431, 1860, 
Limnea tenuicostatus Binney, L. and F. W. Sh. N. Ping lle pecs a age 
Limnea tenuicostata Binney, Journ. de Conch., XV, p. 428, 1867—Wuite, 
3rd An. Rep. U. S. Geol. Surv., p. 445, pl. 23, fig. 24, 1883.—Fiscuer, Man. de 
