LYMN/ZIDA OF NORTH AMERICA. 29% 
1826. Lymnea Risso, Hist. Nat. Eur. Mer., IV, p. 94, first sp. L. pereger (Miil- 
ler). Not Lymnea Rafinesque, Pisces, 1815. 
1830. Stagnicola Jerrreys, Linn. Trans., XVI, ii, p. 376, May 29 (type L. palus- 
tris (Miller) ). 
1831. Stagnicola Turton, Man., pp. 121-124, Oct., 1831. 
1833. Limnophysa Firzincer, Syst. Verz., p. 112 (type L. palustris (Miller) ). 
1838. Limnophysa Breck, Index, p. 110. 
1840. Stagnicola Gray’s TuRTON, pp. 237-242. 
1864. Limnophysa Morcu, Vidensk. Meddel. 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 Dart, Ann. Lyc. 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 MicwHeEner, Conch. Cestrica, p. 64. 
1876. Limnophysa MEEK, Rep. U. S. Geol. Surv. Terr., IX, p. 533. 
1876. Omphalia ‘Rar.’ MEEK, Rep. U. S. Geol. Surv. Terr., IX, p. 532, in Syn.; 
ere. pro. Omphiscola Raf. 
1880. Limnophysa Cr. & Fiscu., Mis. Cient. Mex., II, p. 49. 
1881. Lymnophysa (Fitzincer) Hazay, Mal. Blatt., II], p. 163. 
1884. Limnophysa Tryon, S. & S. Conch., III, p. 101. 
1905. Stagnicola Dati, Alaska Moll., p. 64. 
1908. Stagnicola Baker, Science, n. s., XX VII, p. 943. 
1909. Lymnea 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- 
niellar region, forming an impervious or narrowly open axis; sculpture 
of strong growth lines and equally strong spirally impressed lines, 
forming a notably decussated pattern. (Pl. XVIII, figs. 4, 10.) 
RapuLA: 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 more 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 
