OF NORTH AMERICA. 91 



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 Lymncea 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 (pi. 5, fig. 14) agrees perfectly with 

 his description. The next published figures are in the Fortieth Parallel 

 Report, IV, pi. 17, 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, pi. 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 unpublished figures (figs. 1, 2) and also a view of one of the type 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 Lymncea similis Meek as figured in the Third Annual 

 Report, pi. 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 made by Meek in labeling his unpublished figures, which certainly do 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. 



Pleurolimnaea tenuicosta (Meek and Hayden). Plate XVI, 

 figures 9-11 ; Plate XVII, figure 4. 



Limnaa tenuicosta MEEK and HAYDEN, Proc. Phil. Acad., p. 119, 1856; 

 Amer. Jour. Sci., ii, XXII, p. 428, 1856. MILLER, Jour. Cin. Soc! N. H., Ill, p. 

 21, 1880; Mes. and Caen. Geol., p. 57, 1881. 



Limncza tenuicosta MEEK and HAYDEN, Proc. Phil. Acad., p. 278, 1856. 



Limn&a (Acella) tenuicostata MEEK and HAYDEN, Proc. Phil. Acad., p. 

 431, 1860. 



Limn&a tenuicostatus BINNEY, L. and F. W. Sh. N. A., II, p. 72 1865. 

 Limncea tenuicostata BINNEY, Journ. de Conch., XV, p. 428, 1867. WHITE, 

 3rd An. Rep. U. S. Geol. Surv., p. 445, pi. 23, fig. 24, 1883. FISCHER, Man. de 



