240 THE CHICAGO ACADEMY OF SCIENCES. 
BRITISH AMERICA. 
Ontario: Ottawa, Carleton Dist. (Heron) ; Carleton Co. (Walker). 
GEOLOGICAL RANGE: Unknown. 
Ecotocy: Abundant in still water in sheltered borders of rivers, 
in small brooks, ditches and streams and in shallow overflows. Clings 
to dead leaves or other submerged debris or crawls over the muddy 
bottom of its habitat, in shallow water. Associated with Galba obrussa, 
Aplexa hypnorum and the small planorbes (Baker). In ditches and 
brooks in pastures (True). Common in damp places and in ditches 
along roads where water collects only in rainy weather (Nylander). 
RemMARKS: ‘The shell of wmbilicata may be distinguished from 
cubensis by its smaller size, longer spire, less globose body whorl, 
rounder spire whorls and by the less triangular and more erect inner 
lip, which is peculiarly rolled over in cubensis. In half-grown speci- 
mens the spire is a trifle shorter than the aperture, but in mature indi- 
viduals the spire is as long, or even a trifle longer, than the aperture. 
In umbilicata the center of rotundity of the body whorl is nearer the 
anterior end than in cubensis, the latter being decidedly effusive an- 
teriorly. Specimens are occasionally found with a pink columella. 
Umbilicata differs from humilis in the shape of the inner lip, which 
forms a broad, flat, rolled up shelf, while in humilis it is narrow and 
the margin is rolled in instead of up. The shell of wmbilicata 1s also 
more elongate and regularly long-ovate than that of humilis. 
For the past eighteen or twenty years Adams’ Lymnea umbilicata 
has been a puzzle to students of the Mollusca, and a number of very 
diverse opinions have been published concerning it. By some it has 
been considered a synonym of caperata, by others a variety of the same 
species, and by a few a synonym of cubensis Pfeiffer. The history of 
the treatment of wmbilicata is interesting. Adams described the species 
in 1840 in the American Journal of Science and figured it in the Boston 
Journal of Science. Haldeman, in his monograph, in 1842, considered 
it a synonym of caperata. The earlier students—Lewis, Tufts, True, 
Currier, Beauchamp, etc.—considered it a distinct species. Tryon, in 
his Catalogue (American Journ. Conch., 1, p. 255), placed it in the 
synonymy of caperata. Binney placed it under caperata in his mono- 
graph, but treated it as possibly distinct in Binney’s Gould. Baker and 
Daniels, in their papers on the Mollusca of Illinois and Indiana, have 
considered it a variety of caperata with short spire and bulbous whorls. 
Dall, in his Alaska Molluska, places it in the synonymy of caperata. 
In 1891, Pilsbry (Proc. Phil. Acad., 1891, p. 321) stated as fol- 
lows: “The L. umbilicata C. B. Ad. is completely synonymous with 
