236 THE CHICAGO ACADEMY OF SCIENCES. 
Subgenus SIMPSONIA Nov. Subgen. 
Type: Limnea humilis Say. 
SuetL: Similar in general form to that of Galba. 
RapuLa: With tricuspid lateral teeth. 
GENITALIA: Similar to Galba. 
This group of small Lymnzeas is separated from the subgenus 
Galba mainly on account of the radula, which has tricuspid instead of 
bicuspid laterals. The shell offers no definite characters of group value 
by which to separate Simpsonia from Galba, The subgenus contains 
the humilis-obrussa-parva group of Lymnzeas, in which the sheil is 
usually small and without marked spiral sculpture. It is mainly con- 
fined to the northern part of the United States and Canada. 
Galba umbilicata (C. B. Adams). Plate XXX, figures 1-7. 
Limnea umbilicata C. B Avams, Amer. Journ. Sci., i, XXXIX, p. 374, 
1840.—Bost. Journ. Nat. Hist., III, p. 325, pl. iii, fig. 14, 1840—Taytor and 
SHIVERICK, Cat., 1840.—GouLp, Invert. Mass., p. 218, fig. 149, 1841—Prescort, 
Cat. Sh. Mass., No. 198, 1842.—RereEp, Cat., 1845.—RussELL, Journ. Essex Co. 
Nat. Hist. Soc., p. 130, 1852—Lerwis, Proc. Bos. Soc. N. H., VI, p. 2, 1856 
(part) —Turts, Proc. Essex Institute, I, p. 30, 1856—True, Proc. Essex Inst., 
II, p. 195, 1857 —Wuiteaves, Can. Nat., VIII, p. 103, 1863—Brnney, L. & F. W. 
Sh. N. Am., II, p. 57, fig. 88, 1865.—GouLp, Binney Ed., Inv. Mass., p. 480, 
fig. 731, 1870.—JEFFREYs, Ann. Mag. N. H., ser. IV, X, p. 247, 1872 (part) ; 
Journ. Conch., I, p. 8, 1874 (part).—H. F. Carpenter, Random Notes, III, p. 86, 
1886.—Pitspry, Proc. Phil. Acad., p. 320, 1891. 
Lymnea umbilicata Lea, Journ. Phil. Acad. VI, pp. 161, 162, 1866; Obs., 
XI, pp. 117, 118, 1867.—Scupper, Bull. Nat. Mus., 23, p. 201, 1885—-WALKER, 
Nautilus, XXII, pp. 7, 8, figure 1, pl. 2, figs. 1, 2, 1908; Ottawa Nat., XXII, pp. 
90-91, fig. 3, 1908—LeERMonpD, Shells of Maine, p. 37, 1909—Baxker, Nautilus, 
XXIII, p. 80, 1909. 
Lymnea caperata var. umbilicata Jay, Cat. Ed. 4, p. 268, 1852. 
Limnea umbilicata Hautp., Mon. Limn., p. 34, pl. 11, fig. 9, 1842. 
Limneus umbilicatus CLessin, Mal. Blatt., n. s., III, p. 83, 1881. 
Limnea umbilicata JAcKson, Nautilus, XXI, p. 142, 1908. 
Limnea humilis Heron, Ottawa Nat, I, p. 39, 1880—NyLanpver, Nautilus, 
VIII, p. 126, 1895; XIII, p. 104, 1900—Lermonp, Shells of Maine, p. 38, 1908 
(part). 
Lymnea grifithiana Lea, Proc. Amer. Phil. Soc., II, p. 33, 1841; Trans. 
Amer. Phil. Soc., IX, p. 8, 1844; Obs., IV, p. 8, 1848. 
Lymnea grifithiana WHEATLEY, Cat. Sh. U. S., Ed. 2, p. 23, 1845.—Scup- 
pER, Bull. Nat. Mus., 23, pp. 43, 201, 1885. 
Limnea grifithiana Brnney, Check List, p. 12, 1860; Land and F. W. Sh. 
N. A., II, p. 66, fig. 107, 1865—Tryon, Amer. Journ. Conch., III, p. 196, 1867; 
Con. Hald. Mon., p. 105 (79), pl. 18, fig. 5, 1872—-Cressin, Mal. Blatt., n. s. 
Tk. Si. 1881. 
Limnea cubensis Crosse & FiscHer, Pitspry, Von Martens, etc. (not 
Prr.). 
