LYMNA:IDZ2 OF NORTH AMERICA. 285 
from Thomaston and Unity, Maine, seem referable to this variety. A 
form of obrussa occurs at Castle Hill, Aroostook County, which some- 
what resembles this variety, differing in having a larger aperture and 
a narrower body whorl. These are probably transition forms. Penin- 
sul@ will probably be found in collections labeled desidiosa. 
Galba obrussa exigua (Lea). Plate XXXII, figures 7-14. 
Lymnea exigua Lea, Proc. Amer. Phil. Soc., I pr 33,1841; (rans. Ames: 
Phil. Soc., IX, pp. 9, 10, 1844; Obs., IV, pp. 9, 10, 1848; Proc. Phil. Acad., VIII, 
p. 81, 1856; Journ. Phil. Acad., VI, pp. 155, 162, 1866 ; Obs., XI, pp. 111, 118, 1867. 
Lymnea exigua WHEATLEY, Cat. Sh. U. S., p. 23, 1843.—Lera, Proc. Phil. 
Acad., 1856, p. 81—Cpr., Rep. Brit. Asso., 1864, p. 634.—WOLF, Amer. Journ. 
Conch., VI, p. 28, 1870—Cpr., Smith. Mis. Pub., 1872, p. 120—Scupper, Bull. 
Nat. Mus., 23, pp. 33, 43, 201, 1885. 
Limnea cxigua D’UrsaNn, Geol. Surv. Can. Rep. Prog., p. 242, 1859.—BIN-_ 
wey, Check List, p. 12, 1860; L. & F.-W. Sh. N. A,, I, p: 65, fig. 105, 1865.— 
Wuiteaves, Can. Nat. & Geol., VIII, p. 103, 1863.—Tryon, Amer. Journ. Conch., 
III, p. 196, 1867—Ctessin, Mal. Blatt., n. s., III, p. 81, 1881. 
Limnophysa humilis var. exigua Cooper, Proc. Cal. Acad. Scie Ven pega: 
1870. . 
Lymnea plica Lea, Proc. Amer. Phil. Soc., II, p. 33, 1841; Trans. Amer. 
Phil. Soc., IX, pp. 8, 9, 10, 1844; Obs., IV, pp. 8, 9, 10, 1848; XI, p. 118, 1867; 
Journ. Phil. Acad., VI, p. 162, 1866. 
Lymnea plica WHEATLEY, Cat. Sh. U. S., p. 23, 1843—Scupper, Bull. Nat. 
Mus., 23, pp. 33, 44, 201, 1885. 
Limnea plica Binney, Check List, p. 12, 1860; L. & F.-W. Sh. N. A,, Wd, 
p. 65, fig. 103, 1865——Tryon, Amer. Journ. Conch., III, p. 196, 1867.—CLESSIN, 
Mal: Blatt., nis., DI, p. 81, 1881. 
Limnea plicata D’UrBAN, Geol. Surv. Can., Rep. Prog., p. 242, 1859. 
Lymnea obrussa plica BAKER, Bull. Ill. State Lab. N. H., VI, p. 103, 1906. 
Lymnea planulata Lea, Proc. Amer. Phil.'Soc., II, p. 33, 1841; Trans. Amer. 
Phil. Soc., IX, p. 9, 1844; Obs., IV, p. 9, 1848. 
Lymnea planulata WHEATLEY, Cat. Sh. U. S., p. 23, 1843—Scupper, P 
Nat. Mus., 23, pp. 33, 44, 201, 1885. 
Limnea planulata Binney, Check List, p. 12, 1860; L. & F.-W. Sh. N. A,, 
II, p. 65, fig. 104, 1865.—Cressin, Mal. Blatt., n. s., II, p. 81, 1881. 
SHELL: Small, turreted, subfusiform, generally narrow; surface 
dull to shining, growth lines coarse, elevated, crowded; spiral lines 
sometimes present; whorls 5, generally well rounded, slowly increasing 
in diameter; spire wide, elevated, turreted, generally longer than the 
aperture; nuclear whorls as in obrussa; sutures deeply impressed ; 
body whorl generally compressed, subcylindrical; aperture ovate to 
elliptical, slightly effuse; outer lip thin; inner lip narrow, tightly ap- 
pressed at its junction with the parietal wall, the lower part erect or 
turned upward; umbilical chink very small, frequently entirely closed. 
