VI II THE CHICAGO ACADEMY OF SCIENCES. 



Latham, V. A., Chicago, Ills. 



Lermond, N. W., Thomaston, Me. 



Letson, Miss E. J., Buffalo Society of Natural History, Buffalo, N. Y. 

 (Now Mrs. W. A. Bryan, of Honolulu.) 



Lyon, Howard X., Chicago, Ills. 



MacCurdy, H. A., Alma, Mich. 



Marsh, Win. A., St., Aledo, Ills. 



Mazyck, William G., Charleston, S. C. 



Morse, Edward S., Director, Peabody Museum, Salem, Mass. 



Xason, William A., Algonquin, Ills. 



Nylander, Olof. 0., Caribou, Me. 



Ortmann, A. E., Carnegie Museum, Pittsburg, Penn. 



Over, W. H., Date, South Dakota. 



Pease, A. S., University of Michigan, Ann Arbor, Mich. 



Rathbun, Richard, U. S. National Museum, Washington, D. C. 



Sargent, H. E., Grand Rapids, Mich. 



Selden, Charles W., Valley City, North Dakota. 



Simpson, Charles T., Little River, Florida. 



Southwick, James M., Roger Williams Park Museum, Providence, R. I. 

 (Deceased.) 



Stearns, Robert E. C, Los Angeles, Cal. (Deceased.) 



Sterki, Victor, New Philadelphia, Ohio. 



Streng, L. H., Grand Rapids, Mich. 



Strode, W. S., Lewistown, Ills. 



Van Hyning, T., Des Moines, Iowa. 



Wagner, George, University of Wisconsin, Madison, Wis. 



Walker, Bryant, Detroit, Mich. 



Walker, Miss Mary, Buffalo, N. Y. 



Walter, H. E., Brown University, Providence, R. I. 



Ward, F. H., State Museum, Albany. N. Y. 



Weller, Stuart, University of Chicago, Chicago, Ills. 



Wiswall, Mrs. E. C, Madison, Wis. 



Woodruff, Frank M., Chicago Academy of Sciences, Chicago, Ills. 



Youngren, Emil W., Chicago, Ills. 



Zetek, James, State Laboratory of Natural History, Urbana, Ills. 



SUMMARY. 

 The work is divided into chapters, each chapter dealing with a 

 distinct phase of the subject. The morphology (I) is necessarily 

 brief, and is intended simply to outline the gross anatomy of the Lym- 

 naeas in such a manner as to convey a clear idea of the structure of 

 these animals. Under Ecology (II) is given a brief account of the 

 habitat relations of the family, as well as notes on food, reproduc- 

 tion, respiration, aestivation, locomotion, etc., which it is hoped may 

 prove useful to those interested in the modern science of animal ecol- 

 ogy. It is believed that the photographs of typical habitats will aid not 

 a little in the understanding of this subject. Exact data concerning 

 the habitat relations of our fresh-water shells is very meager and there 



