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It has been thought of value in this connection to list all those 
species of animals which have been found directly associated with 
the mollusks in their various habitats. Thus, if a beetle was found 
under bark with a mollusk it was secured and listed with the mol- 
luscan species found at this station. So, also, the aquatic insects 
were listed in connection with the aquatic mollusks. 
As an ecological survey is not complete without a knowledge of 
the plant societies, the more characteristic plants have been listed 
in connection with the various habitats. This list does not pretend 
to completeness, its purpose being to indicate those species of plants 
most intimately associated with the molluscan habitats. 
At the time the survey was made, a collection of the nesting 
birds of the Skokie region was secured for the museum of the 
Academy, and it has been thought of value to include a few notes on 
these. 
ACKNOWLEDGMENTS. 
My thanks are due to the following persons who have greatly 
aided in the work of the survey: 
To Dr. H. C. Cowles, University of Chicago, and Miss Carrie A. 
Reynolds, Lake View High School, for identifying the majority of 
the plants; to Mr. V. E. Shelford, University of Chicago, Mr. Chas. 
A. Hart, of the State Laboratory of Natural History, and Mr. 
J. J. Davis, Assistant to the State Entomologist, for assistance in 
working up the insects; to Mr. A. E. Ortmann, of the Carnegie 
Museum, Pittsburg, for the identification of the crawfishes; and to 
Mr. Frank M. Woodruff and Mr. Edward R. Ford for assistance 
in the determination of the birds as well as for many notes and sug- 
gestions on the same. 
The photographs of habitats have been made by Mr. F. M. Wood- 
ruff, of the Chicago Academy of Sciences, and the author. On each 
photograph the name of the photographer appears in parenthesis. 
Economic CONSIDERATIONS. 
An area such as is herein described has a distinctly economic 
value, affording, as it does, both concealment and food for verte- 
brate life. The birds find excellent protection for their young in 
the thick vegetation, and abundant food is provided in the numer- 
ous ponds, streams and woodlands. The habitats are especially 
