28 THE CHICAGO ACADEMY OF SCIENCES. 



Magnolia, Boulder County, Colorado, 9000 feet altitude (Henderson;. 



In creek, Uintah Mountains, 10,000 feet altitude 1 (Bailey; Dallh 



Mt. Leidy, in stagnant pond at 10,000 feet altitude (Dall). 



Xo exact data is available on the bathymetrical range of the 

 American Lymnaeas ; it is quite probable that several species live at 

 considerable depths in the great lakes, notably z^oodruffi, the animal 

 of which has never been seen. Some of the smaller lakes undoubtedly 

 have a deep-water Lymnseid 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 : 



Lymncea stagnalis, Lake Geneva, Switzerland, 250 meters (Forelh 



Lymncea aurkularia, Lake Constance, Switzerland, 70 meters (Siebold). 



Lymneea auricularia, Lake Geneva, Switzerland, 40 meters (Andre . 



Lymncea abyssicola, Lac Leman, Switzerland, 25-250 meters (Forel). 



Many Lymnaeas, as well as other pulmonates, have been found 

 in thermal springs; thus, Lymncea peregra and Physa acuta live in 

 the thermal waters at Barbatan, France, where the temperature reaches 

 S6 : . Lymncea pcrcgra var. geiscrcola lives in the hot water of the 

 geysers of Iceland (vide Morch). 



Lymnaea is also known to live in brackish or even salt water. 

 FriedeP records the living together in brackish water of Lymncea and 

 Neritina with small specimens of Mya arenar'xa, Cardxum cdule, Car- 

 dinal rusticum, Rissoa and Littorina. In the area of the Quaternary 

 lakes Bonneville and Lahontan, several species of Lymnaeids live in 

 more or less brackish or alkaline waters, notably Galba palustris. 



The Lymnaeids are able to withstand a very low as well as a high 

 temperature. It is recorded that Lymncea auricularia 2, has been frozen 

 in a solid mass of ice and has subsequently revived after being thawed 

 out. Lymnaeas have also been seen to crawl about on the under surface 

 of a coating of ice. 4 



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 6 record that Sphcerium, 



J At Iskardo and Xubra. in Tibet. Lvmnaea hookeri lives at an altitude of 

 18,000 feet, r Woodward. P. Z. S.. 1856. p. 185.) 



! Mal. Blatt. XVII. p. 56; Jordan, 1883. p. 236. 



5 Bull. Soe. Linn. Xord.. Abbeville, 1840, p. 150. 



4 Cooke. Mollusea. p. 2 7. 



'Bull. Soc. Vaudoise des Sei. Xat.. X. p. 217. 1869; XIII, p. 1. 1S74: Andre, 

 Journ. Malac. VIII, p. 35. 1901. 



Mourn, de Conch, XXII, p. 332. 



