Plate IIIB 



Fig-. 1. Crawfish chimney at Station I, Charleston, 111. Probably formed by Cambarus gracilis or 

 diogenes. (Photograph by T. L. Hankinson.) 



^mmm. 







Fig 1 . 2. General view at Station I. i/, showing numerous crawfish chimneys, probably formed by 

 Cambarus gracilis or diogencs. (Photograph by T. L. Hankinson.) 



