THE DRAWING OF THE SEINE. 171 



ditch, not one could have been the result of accident, as 

 suggested by Mr. Tarr. 



The towers that were found in the meadows, at a con- 

 siderable distance from open water, were invariably 

 broader at the base and never so high as those described 

 as found on the edge of flowing water. These open- 

 meadow towers or chimneys, however, were all found to 

 be composed of pellets of clay so arranged as to render 

 it highly improbable that their positions were fortuitous. 

 Indeed, in the majority of instances it would have been 

 practicable to have rolled the little balls of clay to a con- 

 siderable distance from the opening of the tunnel. 



Perhaps there is a bearing on the question of design 

 in tower-building in the fact that often half-grown or 

 even smaller crayfish of this species build the most elab- 

 orate structures. Some of the finest examples, i. e., the 

 most slender and tallest, were the work of diminutive 

 little fellows which certainly could have avoided a deal 

 of labor if the chimneys or towers were not designed. 



But how does the burrowing crayfish build these chim- 

 neys ? I am forced to admit they have, as yet, overtaxed 

 my patience, and from personal knowledge I can only 

 assert that the work is done only at night, and that often 

 in a single night a tall and stately chimney will be 

 reared. 



Others have been more fortunate, and my nephew 

 informs me that he has seen the crayfish at work. Find- 

 ing, one evening, the base of a chimney about one and 

 a half inches in height, he remained for some time to 

 get a glimpse of the occupant. In this he was unsuc- 

 cessful; so the following evening he determined to 



