NESTING ARCHITECTURE 



among the bones of extinct creatures of the geologic 



ages. 



These roofing pebbles are not i.or but sparsely) inter- 

 mingled with the soil of which the interior bulk of the 



fj 



cone is composed, but form a stone covering, or roof, about 

 a half inch thick, more or le . Mr. H. L. Viereck in- 

 formed me that he had seen bits of cinder and coal, 

 evidently gathered from the railroad track, for roofing. 

 This is confirmed by the statement of Mr. G. A. Dean 

 [D. 1, p. 1(59]. who further says that on the old town 

 site of Wallace. Kansas, they used bits of glass, mortar, 

 and small fragments of rusted iron from the debris of 

 ruined house-. Thus the roofing habit, though it may 

 have originated from the accidental deposit of ex- 

 cavated pebblets. seems to have grown into a fixed 

 purposeful instinct that prompts to gather supple- 

 mentary material from any available quarter. 



The pebbles are handled with ease by the worker- 

 ants, who nip them with their outstretched mandibles 

 and then move off. rarely stopping en route to adjust 

 the burden or to rest. The body is lifted up. the head 

 well elevated to prevent bumping against the surface, 

 and the load held well to the front or somewhat beneath 

 the body. The portage was amply observed during 

 ordinary excavations, in opening and closing gates, and 

 in repairing breaks caused by rains or purposely made 

 for experiment. In the last-named work the ants 

 would descend to the clearing at the base of the cone, 

 and carry the stones up the slope with as little apparent 

 effort as when moving downward. 



This, however, must be an easier task than transport- 

 ing them from distant sites or from their interior beds 

 up the galleries to the surface. The space traversed in 



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