LYMN^ELLVE OF NORTH AMERICA. 291 



RECORDS. 



United States. 

 marl deposits. 

 Illinois : Chicago, Clyde Avenue, near Austin Avenue, six feet beneath 

 surface, Cook Co. (Scharf). 



Maine:' Barren Brook, Caribou, Aroostook Co. (Nylander). 

 Michigan : Pickerell Lake, Newaygo Co. ; Marsh north side of Cedar 

 Lake, Cedar Lake Station, Montcalm Co. (Walker). 



Wisconsin: Milwaukee, Milwaukee Co. (Baker; Slocum). 



OTHER POST-GLACIAL DEPOSITS. 



Michigan: Celery Swamp, Ann Arbor, Washtenaw Co. (Walker). 



New York : West Chartton, Saratoga Co., in extinct lake, under six feet 

 of muck (H. B. McWilliams). 



Ecology : The habitat of decampi is probably the same as that 

 of obrussa. 



Remarks : Decampi is a very distinct and characteristic variety 

 of obrussa, known at once by its strongly shouldered whorls and the 

 peculiar manner in which the outer lip is arched at its junction with 

 the body whorl. It appears to be one of the most common of the 

 Pleistocene species and no doubt lived, with galbana, in the more or 

 less icy waters of Post-Glacial Times. Small specimens may be con- 

 fused with galbana, but that species does not have the elongate aper- 

 ture nor the distinctly shouldered whorls of decampi, the aperture being 

 rounder and the shell much heavier and more robust in galbana. De- 

 campi varies greatly in the comparative height of the spire; examples 

 from the same locality will embrace individuals with a long, slender 

 spire and with a short, dome-shaped spire. The aperture also varies 

 somewhat. The figures on plate XXXII illustrate this variation. 



Galba galbana (Say). Plate XXXII, figures 23-36. 



Lymneus galbanus Say, Journ. Phil. Acad., V, p. 123, 1825; Binney's Ed., 

 p. 114, 1858. 



Lymnoea galbana Gould, Lamarck's Genera, p. 69, 1833. — Baker, Trans. 

 St. Louis Acad., XVI, p. 13, 1906.— Walker, Rep. Geol. Surv. Mich., 1905, p. 465, 

 1906. 



Limncsus galbanus Leidy, Proc. Phil. Acad., II, p. 281, 1845. 



Limnea galbana Haldeman, Mon. Limn., p. 51, pi. 13, figs. 22, 23, 1842. 



Lnnnaza galbanus D'Urban, Geo. Surv. Can., Rep. Prog., p. 242, 1859. — 

 Whiteaves, Can. Nat. & Geol., VIII, p. 103, 1863. 



Limncea galbana Binney, Check List, p. 12, 1860; Land & F. W. Sh. N. A., 

 II, p. 72, fig. 117, 1865.— Currier, Kent. Sci. Inst., Mis. Pub., No. 1, 1868 — 

 Sowb., Conch. Icon., XVIII, Lim. sp. 107, pi. 15, fig. 107, a, b, 1872. — Clessin, 

 Mai. Blatt., n. s., Ill, p. 82, 1881.— Walker, Nautilus, VI, p. 34, 1892 ; Rev. Moll. 

 Mich., 1894, p. 18.— Taylor, Ottawa Nat., VIII, p. 147, 1895.— Ami., Ottawa 

 Nat., XI, p. 26, 1897.— Baker, Nautilus, XVII, p. 39, 1903.— Whiteaves, Rep. 

 Geol. Surv. Can., p. 163, 1905. 



