INTERNAL RELATIONS OF TERRESTRIAL 

 ASSOCIATIONS 



ARTHUR G. VESTAL 



studies, during the past five years, of terrestrial associa- 

 tions of plants and animals, mainly in different parts of 

 the prairie region. The particular area chiefly used for 

 illustration in this paper is the sand prairie of the Illinois 

 River valley, plants and animals of which have been 



ana by the writer ( V.)Un). The chief representation of 



