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THE CHICAGO ACADEMY OF SCIENCES. 
Urau: Deception Lake, 8 miles from Kanab, Kane Co. (Daniels and 
Ferriss). 
GEOLOGICAL DisrriBuTIon: Pleistocene. 
RECORDS. 
MicuHI1GAN: Kegomic, Emmet Co., in marl beds (Slocum). 
EcoLtocy: On damp mud flats and in other situations similar to 
those under which modicella is found. 
REMARKS: ustica appears to be a modification of the humilis 
type of shell, characterized principally by its long, very acute spire 
and ovate aperture. Its long, pointed spire will distinguish it from 
any form of modicella. It is liable to be confounded with forms of 
Galba obrussa exigua, but in that race the aperture is longer and 
narrower and inclined to be squarish, while in rustica it is more acutely 
rounded at the extremities. The spire in rustica is longer and more 
acute than in evigwa, the spire whorls being less inflated. Half-grown 
specimens of obrussa are similar in general form, but differ in the 
form of the aperture, which is longer and narrower and forms a dis- 
tinct shoulder at the junction of the outer lip with the body whorl, 
while in rustica this part of the lip is gracefully curved. The aperture 
is sometimes almost round and the spire varies much in height. Rustica 
is evidently more nearly related to modicella than to obrussa and may 
be considered a variety of humilis. 
The type of rustica is not in the Smithsonian collection and is 
probably lost. Lea’s description and the figure in Binney’s work, how- 
ever, leave no doubt as to the kind of sheil Lea had in mind. A single 
specimen in the Lea collection in the Smithsonian Institution is marked 
rustica and agrees fairly well with Lea’s description. It is No. 118652. 
Careful search will undoubtedly reveal this neat little variety in many 
collections, labeled humilis or obrussa. 
Galba obrussa (Say). Plate XXVI, figures 8-13; plate XXXI, 
figures 20-37. | 
Lymneus obrussus SAy, Journ. Phil. Acad., V, p. 123, 1825; Binney’s Ed., 
p. 113, 1858. 
Lymnea obrussa Goutp, Lamarck’s Genera, p. 69, 1833——WHEATLEY, Cat. 
Sh. U. S., p. 23, 1843.—Jay, Cat., p. 270, 1852,—Datt, Land & F. W. Sh: p. 72; 
fig. 51, 1905—Baker, Bull. Ill. State Lab., VII, p. 103, 1906—-HENDERSON, 
Univ. Col. Studies, IV, pp. 93, 179, fig. 34, 1907; Univ. Col. Studies, IV, p. 158, 
1907.—DaniEts, Nautilus, XXII, p. 120, 1909—WatkeEr, An. Rep. Mich. Geol. 
Surv., 1908, p. 290, 1909.—BaxkeEr, Nautilus, XXIII, p. 94—Berry, Nautilus, 
XXIV, p. 62, 1910. 
Limneus obrussa KUsteR, Conch. Cab., p. 51, taf. 11, fig. 19-21, 1862. 
Limnea obrussa BINNEY, Check List, p. 12, 1860; Land & F. W. Sh. N. A., 
II, p. 49, fig. 69, 1865——Tryon, Amer. Journ. Conch., III, p. 196, 1867.—Woop, 
Nautilus, V, p. 54, 1891—Kerep, West. Amer. Sh., p. 314, 1904. 
