184 THE CHICAGO ACADEMY OF SCIENCES. 



Bulimnca differs genetically from the rest of the family in its 

 peculiar bulimiform, darkly colored shell, its long, club-shaped penis, 

 and large and irregular prostate. The penis is very peculiar, being 

 very long, and gradually increasing in diameter to the end, which is 

 cut off almost squarely and not rounded as in other Lymnseas ; the 

 end is more than double the diameter of the organ as it leaves the 

 penis-sac; the protractor muscles of the penis-sac are also more nu- 

 merous than in any groups excepting Lymn&a. 



Bulimnea megasoma (Say). Plate XXV, figures 1-6. 



Lymn&us mcgasomus SAY, Rep. Long's Exp., II, p. 263, pi. 15, fig. 10, 

 1824; Binney, reprint, p. 129, 1858. 



Limn&us megasomus KUSTER, Conch. Cab., ed. ii, p. 36, taf. 6, figs. 20, 21, 

 1862. 



Limnea megasoma HALDEMAN, Mon. Limn., p. 13, pi. 3, figs. 1-3, 1841. 

 DEKAY, Zool. N. Y., p. 70, pi. 4, fig. 70, 1843. LAPHAM, Trans. Wis. St. Agr. 

 Soc., II, p. 368, 1852. KIRTLAND, Trans. Clev. Acad. Nat. Sci., II, p. 6, 1854. 

 BEAUCHAMP, L. and F. W. Sh. N. Y., p. 9, 1886. 



Limncea megasoma C. B. ADAMS, Amer. Journ. Sci., XL, p. 267, 1841. 

 BELL, Can. Nat. and Geol., IV, p. 213, 1859. C. B. ADAMS, Thomp. Hist. Vt, 

 p. 153, 1842 (nee. fig.) ; pamphlet, p. 3. STIMPSON, Sh. N. Eng., p. 52, 1851. 

 BINNEY, Check List, p. 12, I860. LAPHAM, Proc. Phil. Acad., p. 155, I860. 

 BELL, Can. Nat. and Geol., VI, p. 43, 1861. WHITEAVES, Can. Nat. and Geol., 

 VIII, p. 102, 1863. BINNEY, L. and P. W. Sh. N. A., II, p. 37, fig. 46, 1865. 

 CURRIER, Kent. Sci. Inst, Mis. Pub., No. 1, 1868. GOULD, Binney's ed., p. 470, 

 fig. 722, 1870. BLAND .and BINNEY, Amer. Journ. Conch., VII, p. 162, 1871. 

 TRYON, Con. Hald. Mon., p. 94 (68), 1872. SMITH, Rep. U. S. Fish Com., p. 

 701, 1874. WALKER, Journ. Conch., II, p. 330, 1879. CR. and FISCH., Moll. Mex., 

 II, p. 41, 1880. HYATT, Amer. Nat., XIV, p. 51, 1880. BALL, Bull. Phil. Soc. 

 Wash., Ill, p. 75, 1881; Smith. Mis. Coll., XX, p. 75, 1881. Trans. Ottawa 

 Nat. Field Club, I, p. 58, 1882; I, p. 74, 1883. FISCHER, Man. Conch., p. 506, 

 1883. TRYON, S. and S. Conch., Ill, p. 101, pi. 103, fig. 5, 1884. Standard 

 Nat. Hist., I, p. 308, fig. 356, 1884. CHRISTY, Journ. Conch., IV, p. 346, 1885. 

 Trans. Ottawa Nat. Field Club, II, p. 351, 1886. SHIMEK, Bull. Lab. Nat. 

 Hist., Univ. Iowa, I, p. 68, 1888. Ottawa Nat. IV, p. 56, 1890. WALKER, Nau- 

 tilus, VI, p. 32, 1892. TAYLOR, Ottawa Nat., VI, p. 35, 1892. MARSHALL, Rep. 

 N. Y. State Mus., XLVIII, p. 63, 1893. LATCHFORD, Ottawa Nat., VII, p. 115, 

 1893. W^ALKER, Rev. Moll. Fauna Mich., p. 17, 1894. MARSHALL, Rep. N. Y. 

 at World's Fair, p. 510, 1894. SARGENT, Nautilus IX, p. 127, 1896. HANHAM, 

 Nautilus, XIII, p. 5, 1899. BAKER, Shells of Land and Water, pi. and fig. p. 

 18, 1903. WHITEAVES, Rep. Geol. Surv. Canada, p. 163A, 1905. LETSON, Bull. 

 N. Y. State Mus., LXXXVIII, p. 52, 1905. CHADWICK, Nautilus XX, p. 22, 

 1906; Bull. Wi's. Nat. Hist. Soc., N. S., IV, p. 81, 1906. BAKER, Science, N. S., 

 XXVII, p. 943, 1908. ADAMS, Rep. Geol. Surv. Mich., 1908, p. 20, 1909. 



Limncea megastoma REEVE, Elements of Conch., p. 79, 1860. SOWERBY, 

 Conch. Icon., XVIII, Limn., sp., 11, pi. 2, fig. 121, 1872. (Error in plate, note, 

 pi. 2, fig. 12, not fig. 11.) 



