28 THE CHICAGO ACADEMY OF SCIENCES. 
Magnolia, Boulder County, Colorado, 9000 feet altitude (Henderson). 
In creek, Uintah Mountains, 10,000 feet altitude’ (Bailey; Dall). 
Mt. Leidy, in stagnant pond at 10,000 feet altitude (Dall). 
No exact data is available on the bathymetrical range of the 
American Lymnezas; it is quite probable that several species live at 
considerable depths in the great lakes, notably woodruffi, the animal 
of which has never been seen. Some of the smaller lakes undoubtedly 
have a deep-water Lymnzid fauna, but records of such have not been 
found. 
In Europe considerable attention has been given to this subject, 
Forel’s work on the deep-water fauna of Lac Leman, Switzerland, 
being classic.° 
Among the European records the following are of special interest: 
Lymnea stagnalis, Lake Geneva, Switzerland, 250 meters (Forel). 
Lymnea aurtcularia, Lake Constance, Switzerland, 70 meters (Siebold). 
Lymnea auricularia, Lake Geneva, Switzerland, 40 meters (Andre). 
Lymnea abyssicola, Lac Leman, Switzerland, 25-250 meters (Forel). 
Many Lymneas, as well as other pulmonates, have been found 
in thermal springs; thus, Lymnea peregra and Physa acuta live in 
the thermal waters at Barbatan, France, where the temperature reaches 
86°. Lymnea peregra var. geisercola lives in the hot water of the 
geysers of Iceland (vide Morch). 
Lymnza is also known to live in brackish or even salt water. 
Friedel? records the living together in brackish water of Lymnea and 
Neritina with small specimens of Mya arenaria, Cardium edule, Car- 
dium rusticum, Rissoa and Littorina. In the area of the Quaternary 
lakes Bonneville and Lahontan, several species of Lymneids live in 
more or less brackish or alkaline waters, notably Galba palustris. 
The Lymneids are able to withstand a very low as well as a high 
temperature. It is recorded that Lymnea auricularia® has been frozen 
in a solid mass of ice and has subsequently revived after being thawed 
out. Lymnzas have also been seen to crawl about on the under surface 
of a coating of ice.‘ 
A number of observations have been made on the effect of in- 
fected or contaminated water, such as sewage, oil and chemicals, on 
fresh-water mollusks. Crosse and Fisher® record that Spherium, 
1At Iskardo and Nubra, in Tibet. Lymnaea hookeri lives at an altitude of 
18,000 feet. (Woodward, P. Z. S., 1856, p. 185.) 
2Mal. Blatt, XVII, p. 56; Jordan, 1883, p. 236. 
3Bull. Soe. Linn. Nord., Abbeville, 1840, p. 150. 
4Cooke, Mollusca, p. 27. 
5Bull. Soc. Vaudoise des Sci. Nat., X, p. 217, 18697 XIII, p. 1, 1874; Andre, 
Journ. Malac., VIII, p. 35, 1901. 
‘Journ. de Conch, XXII, p. 332. 
