140 THE CHICAGO ACADEMY OF SCIENCES. 



SHIMEK, Bull. Lab. Nat. Hist. State Univ. Iowa, I, p. 67, 1888. 

 KEYES, Bull. Essex Inst., XX, p. 70, 1888. GRANT, An. Rep. Geol. 

 & Nat. Hist. Surv. Minn., XVI, p. 483, 1888. HOLZINGER, An. Rep. 

 Geol. & Nat. Hist. Surv. Minn., XVI, p. 490, 1888. CKLL., Journ. 

 Conch., VI, p. 64, 1889. GILBERT, Mon. U. S. Geol. Surv., I, pp. 

 210, 298, 1890. SHIMEK, Bull. Lab. Nat. Hist. Univ. Iowa, I, p. 67, 

 1890. PILSBRY, Proc. Phil. Acad., pi. XVII, fig. 2, 1890. COOPER, 

 Proc. Cal. Acad. Sci., ii, III, p. 70, 1890. Ottawa Nat., IV, p. 55, 

 1890. STEARNS, Proc. Nat. Mus., XIV, p. 100, 1891. WALTON, 

 Proc. Roch. Acad. Sci., II, p. 11, pi. 6, fig. 9, 1891. LATCHFORD, 

 Ottawa Nat., VI, p. 118, 1892. TAYLOR, Ottawa Nat., VI, p. 35, 

 1892. WALKER, Nautilus, VI, p. 31, pi. 1, fig. 6, 1892. MARSHALL, 

 An. Rep. N. Y. State Mus., XLVII, p. 63, 1893. LATCHFORD, Ottawa 

 Nat., VII, p. 115, 1893. WALKER, Nautilus, VII, p. 128, 1894. 

 MARSHALL, Report Exhib. N. Y. World's Fair, p. 511, 1894 

 BAKER, Science, n. s., II, p. 179, 1895. WALKER, Rev. Moll. Fauna 

 Mich., p. 17, 1895. TAYLOR, Ottawa Nat., IX, p. 174, 1895. SAR- 

 GENT, Nautilus, IX, p. 127, 1896. SNYDER, The Museum, III, p. 12, 

 1896. BAKER, Journ. Cin. Soc. N. H., XIX, p. 84, 1897; The 

 Museum, III, p. 155, 1897. WISWALL, Nat. Sci. Journal, 1, No. 2, p. 

 47, 1897. BAKER, Journ. Cin. Soc. N. H., XIX, p. 78, 1897. AMI., 

 Ottawa Nat., XI, p. 26, 1897. BAKER, Chicago Moll., p. 23, 1898; 

 Trans. Acad. Sci. St. Louis, VIII, p. 88, 1898. WALTON, The 

 Museum, IV, p. 132, 1898. WALKER, Nautilus, XI, p. 122, 1898. 

 HANHAM, Nautilus, XIII, p. 5, 1899. MITCHELL, Nautilus, XIII, 

 p. 88, 1899. PILSBRY, Nautilus, XIII, p. 64, 1899. OSBORN, Pop. 

 Sci., XXXIII, p. 3, 1899. WALKER, Nautilus, XIII, p. 35, 1899. 

 LEVERETT, Mon. U. S. Geol. Surv., XXXVIII, p. 174, 1899. BAKER, 

 Nautilus, XIV, p. 69, 1900. WALKER & LANE, Geol. Surv. Mich., 

 VII., pt. ii, p. 251, 1900. BLATCHLEY & ASHLEY, Rep. Geol. & Nat. 

 Res. Ind., XXV, p. 248, 1901. BAKER, Trans. Acad. Sci. St. Louis, 

 XI, p. 21, fig. 12, pi. 1, fig. 15, 1901. STEARNS, Science, XV, p. 153, 

 1902. WHITEAVES, Ottawa Nat., XVI, p. 91, 1902. ELROD, Bull. 

 Univ. Mont., Biol. Ser., No. 3, pp. 112, 160, 1902. CKLL., Nautilus, 

 XVI, p. 96, 1903. WALKER, Geol. Surv. Mich., VIII, pt. iii, p. 101, 

 1903. BAKER, Shells of Land & Water, p. 11, fig., pi. fig. 18, 1903. 

 KEEP, West. Amer. Shells, pp. 148, 313, fig. 127, 1904. LETSON, 

 Bull. N. Y. State Mus., LXXXVIII, p. 51, 1905. WHITEAVES, Ottawa 

 Nat., XIX, pp. 31, 32, 1905. LETSON, Bull. Buf. Soc. Nat. Sci., IX, 

 p. 242, 1909. 



Limnea stagnalis HALDEMAN, Bost. Journ. Nat. Hist., IV, p. 468, 1844. 

 CARLTON, Proc. Cal. Acad. Sci., i, IV, pp. 51, 57, 1869. FROEBEL, 

 Proc. Lye. Nat. Hist., I, p. 72, 1870. INGERSOLL, Bull. U. S. G. & G. 

 Surv., I, p. 138, 1875; Proc. Daven. Acad. Sci., II, p. 132, 1877. 



Limn&a lanceata, Ottawa Nat., I, p. 58, 1882; IV, p. 58, 1890. 



Limnaa lepida, Ottawa Nat., I, p. 58; IV, p. 56, 1890; VI, p. 33, 1892. 



SHELL: Differing from stagnalis in being more regularly fusi- 

 form, having a less angulated and more gracefully rounded body whdrl 

 and a more pronounced twist of the axis. The spire in typical stagnalis 



