LYMN^ID^E OF NORTH AMERICA. 297 



1826. Lymnea Risso, Hist. Nat. Eur. Mer., IV, p. 94, first -sp. L. pereger (Miil- 

 ler). Not Lymnea Rafinesque, Pisces, 1815. 



1830. Stagnicola JEFFREYS, Linn. Trans., XVI, ii, p. 376, May 29 (type L. palus- 



tris (Muller)). 



1831. Stagnicola TURTON, Man., pp. 121-124, Oct., 1831. 



1833. Limnophysa FITZINGER, Syst. Verz., p. 112 (type L. palustris ( Muller) ). 



1838. Limnophysa BECK, Index, p. 110. 



1840. Stagnicola GRAY'S TURTON, pp. 237-242. 



1864. Limnophysa MORCH, Vidensk. M-eddel. Kjob., p. 298. 



1865. Limnophysa BINNEY, L. & F. W. Sh. N. A., II, p. 38. 

 1865. Omphiscola BINNEY, L. & F. W. Sh., N. A., II, p. 70. 

 1870. Limnophysa DALL, Ann. Lye. N. H., IX, p. 349. 

 1870. Limnophysa COOPER, Proc. Cal. Acad. Sci., IV, p. 96. 

 1872. Limnophysa TRYON, Con. Hald. Mon., p. 87 (61). 



1874. Limnophysa HARTMAN and MICHENER, Conch. Cestrica, p. 64. 



1876. Limnophysa MEEK, Rep. U. S. Geol. Surv. Terr., IX, p. 533. 



1876. Omphalia 'RAF/ MEEK, Rep. U. S. Geol. Surv. Terr., IX, p. 532, in Syn.; 

 ere. pro. Omphiscola Raf. 



1880. Limnophysa CR. & FISCH., Mis. Cient. Mex., II, p. 49. 



1881. Lymnophysa (FITZINGER) HAZAY, Mai. Blatt., Ill, p. 163. 

 1884. Limnophysa TRYON, S. & S. Conch., Ill, p. 101. 



1905. Stagnicola BALL, Alaska Moll., p. 64. 



1908. Stagnicola BAKER, Science, n. s., XXVII, p. 943. 



1909. Lymnaa H. B. BAKER, An. Rep. Mich. Acad. Sci., p. 138. 



SHELL: Elongated, with gradually increasing whorls; outer lip 

 with (usually) a heavy varical thickening just within the aperture, 

 representing a period of rest in the growth of the shell; these varices 

 may be retained as white bands on the earlier whorls of the spire; 

 pillar slightly twisted and plicated; inner lip appressed to the colu- 

 mellar region, forming an impervious or narrowly open axis ; sculpture 

 of strong growth lines and equally strong spirally impressed lines, 

 forming a notably decussated pattern. (PI. XVIII, figs. 4, 10.) 



RADULA : With bicuspid lateral teeth. 



GENITALIA:. With the penis generally shorter than penis-sac; 

 lower portion of oviduct (below first accessory albuminiparous gland) 

 very long and narrow; prostate rather long, flatly rounded, "broadly 

 rounded anteriorly and gradually narrowed posteriorly. 



Stagnicola differs from Simpsonia in its generally mere pronounc- 

 edly sculptured shell, the presence of a plait on the slightly twisted axis, 

 and in the heavier rib or varix within the aperture which marks periods 

 of rest from shell making. The genitalia differ but little, the prostate 

 being longer, with a more broadly rounded proximal end; the lower 

 portion of the oviduct is also longer and narrower. The radula differs 



