LIST OF SHELLS COLLECTED BY VERNON BAILEY IN HERON 

 AND EAGLE LAKES, MINNESOTA, WITH NOTES. 



By Robert E. C. Stearns, Ph. D., 



Honorary Associate in Zoology. 



The species listed below have been received at various times from 

 the United States Department of Agriculture. They form a part of the 

 collection of the United States National Museum, and were collected 

 by Mr. Vernon Bailey, an assistant in the Division of Biological 

 Exploration, in charge of Dr. C. Hart Merriam. 



Heron Lake is in southwestern Minnesota, in Jackson County, near 

 the Iowa line. The material from this place was, to quote Mr. Bailey, 

 " scraped up on the beach," in 1887. 



Eagle Lake is in Sherburne County. This county is nearer the cen- 

 ter of the State, being rather south and east of the center. The collec- 

 tions from both places are small, so far as the number of species is 

 considered, but not without interest, as certain forms, which are com- 

 mented on at some length, indicate ijeculiar environmental conditions. 

 These conditions can only be surmised from the material itself, in the 

 place of personal investigation of the lakes and their waters as well 

 as the iramediateregionin which they are situated. The testimony of the 

 numerous examples of Planorhis trivolvis from Heron Lake and Limncea 

 emarginata from Eagle Lake points to considerable fluctuation in the 

 volume of the water one season compared with another, and in the 

 more northerly Eagle Lake to the influence of extreme cold, or alterna- 

 tions of temperature conditions as related to volume of water in some 

 seasons or years, as well as possible alkalinity or some chemical fluctu- 

 ation due to diminished volume of water at times, or, briefly, to fluctu- 

 ations in the quantity and temperature of the waters and the chemical 

 quality or proportions in the same. 



The Eagle Lake shells were collected in 1891. 



LIMN^A PALUSTRIS Miiller. 

 Heron Lake; a few examples. 



LIMN^A CAPERATA Say. 



Heron Lake; infrequent. 



Proceedings U. S. National Museum, Vol. XXII— No. 1190. 



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