1 62 C. H. TURNER. 



were confused ; then they begin to remove the obstruction. In 

 the meanwhile, the ants in the nest have been tunneling from 

 within. Usually the ants from within are the first to penetrate 

 the obstruction. Occasionally the ants on the outside are the 

 first to make a breach. In one case observed by me, the ants 

 on the outside took no part whatever in removing the obstruc- 

 tion until the ants in the nest had made an opening. When the 

 nest opening is closed with anything which is not too large for 

 several ants acting conjointly to remove, several will cooperate 

 in removing it ; otherwise a new opening is made. I have seen 

 as many as five ants acting conjointly in removing an obstruction. 



FIG. i. FIG. 2. 



FIG. I. Mound of P. badius, surface view, a, entrance ; b, debris, mostly plant 

 matter, from the nest. There were a few pebbles scattered over the mound. The 

 nest contained workers of all sizes and several females. Greatest length, 17 in. ; 

 greatest width, 14 in. 



FIG. 2. Mound of P. baJius, surface view, a, entrance ; b, debris, mostly plant 

 matter, from the nest ; g, stalks of green grass. The top is well covered with 

 pebbles. Greatest length, 24 in. ; greatest width, 20 in. 



The statements in the preceeding paragraph were established 

 by several experiments similar to the following : March 28, 1908, 

 5 P. M. Numerous workers are on the outside of the nest. I 

 fill the opening with sand and small pebbles. Immediatly the 

 workers on the outside of the nest examine the obstruction and 

 then rush about as though they are searching for an opening. 

 5:02 P. M. Several workers try to force an opening through 

 the obstruction. 5:10 P. M. One of the workers confined to 

 the nest succeeds in forcing a passage-way to the outside. Im- 

 mediately three workers begin to remove the pebbles. Up until 

 now, no particle has been removed from the outside of the nest. 

 5:15 P. M. Another worker emerges from within. 5:20 P. M. 

 The opening has been cleared, and the ants are busy bringing 



