166 THE CHICAGO ACADEMY OF SCIENCES. 
Limnea columella var. macrostoma WuiteEAves, Can. Nat. & Geol. VI, 
p. 458, 1861; Can. Nat. & Geol., VIII, p. 102, 1863. 
Lymnea columella var macrostoma Jay, Cat., Ed. 4, p. 261, 1852.—MorseE, 
Amer. Nat., III, pl. 3, fig. 16, 1870—LrErmonp, Shells of Maine, p. 37, 1908. 
Lymnea macrostoma Dexay, Cat. An. N. Y., p. 32, 1839.—Gzirarp, -Proc. 
Nat. Inst., p. 81, 1856—Tryon, Amer. Journ. Conch., II, p. 11, 1866. 
Limnea macrostoma Goutp, Invert. Mass., p. 217, fig. 148, 1841—TAyLor 
and SHIVERICK, Cat., 1840.—Prescott, Sh. Mass., No. 196, 1842.—REAp, Cat., 
1845.—RUuSSELL, Journ. Essex Co. Nat. Hist. Soc., p. 130, 1852.—Turts, Proc. 
Essex Inst., I, p. 30, 1856.—Trur, Proc. Essex Inst., II, p. 195, 1857 —Can. Nat. 
& Geol., I], p. 198, figure, 1857—ReErve, Elements of Conch., p. 179, 1860.— 
Binney, Land & F. W. Sh. N. A., II, p. 34, fig. 39, 1865—Tryon, Amer. Journ. 
Conch., III, p. 196, 1867—Gou Lp, Invert. Mass., ed. Binney, p. 472, f. 724, 1870.— 
Tryon, Con. Hald. Mon., p. 88 (62) pl. 16, fig. 2, 1872——Sows., Conch. Icon., 
XVIII, Lim., sp. 43, pl. 6, fig. 36, 1872.—Cr. and Fiscu., Mis. Scient. Mex., Moll., 
II, p. 52, 1880. 
Limnea macrostoma Harp, Mon. Limn., pl. 12, figs. 1-8, 1842.—LAPHAM, 
Trans. Wis. State Ag. Soc., II, p. 368, 1852—Turts, Cat. Mass. State Cab., p. 
87, 1859. 
Limnea merostoma RAVENEL, Cat. Sh. Cab. Ravenel, p. 11, 1834. 
Radix macrostoma HartMAN and MiIcHENER, Conchologia Cestrica, p. 63, 
fig. 120, 1874. 
' Neristoma macrostoma Tryon, Amer. Journ. Conch., I, p. 248, 1865. 
Radix columella var. macrostoma Prime, Forest & Stream, XV, p. 245, 
1880. 
Limnea acuminata C. B. Aps., Amer. Journ. Sci., XXXIX, p. 374, 1840. 
Lymnea columella var. acuminata Jay, Cat., ed. 4, p. 268, 1852. 
SHELL: Ovate, somewhat pointed, thin, fragile, transparent; color 
light greenish or yellowish horn; surface shining, covered with rather 
coarse growth lines, and encircled by heavily impressed spiral lines ; 
whorls four, well rounded, rapidly enlarging, the last one three times 
the size of the rest of the shell; spire sharply conic, rather short; apex 
small, very dark brown; sutures tightly appressed; a ridge is fre- 
quently formed at the suture where the lines of growth meet the whorl 
above; aperture ovate, dilated, expanded at the lower part; peristome 
thin, acute; inner lip closely appressed to the body whorl and reflected 
over the umbilicus, either completely closing the latter or leaving a 
small, narrow chink; axis slightly twisted; the columellar region is 
so narrow and so peculiarly arched that a view may be taken from 
the base nearly to the apex, as in Succinea retusa; this is especially 
noticeable in the wide shells called macrostoma. The nuclear whorls 
do not differ in outline from those of Lymnea stagnalis. The nucleus 
consists of about 114 smooth whorls. The growth lines are very heavy 
at the beginning of the post nuclear shell. 
