1907.] 



Wheeler, Fungufs-groiciug Ants of North Avierica. 



731 



washed down and fused with one another bv the rains. Several perfect 

 and recently constructed craters arc commonly found on the top or about 

 the edges of the mound, and in the case of large and active colonies these may 

 be numerous, as in the nest shown in Fig. 8, which was situated on the left 

 bank of the Colorado River between Austin and Montopolis. The craters 

 in this instance covered an area of more than 100 sq. m. although the nest 

 had not been in existence long enough to form a distinct mound. They 

 varied from a dcm. to half a m. in diameter and from a few cm. to a dcm. 



Fig. 8. Large Atta teiunii nesi on the left bitiik of the Coloiiitlo Jii\ci beuseeii Austin 

 and Montopolis, Texas. (Photograph by Mr. C. G. Hartmann.) 



high. Their typical form is shown in Fig. 9, which is taken from the nest 

 represented in the preceding figure. The wall of the crater is often higher 

 on one side than on the others, or it may be crescentic, that is, interrupted 

 at one part of the circumference. The opening at the bottom varies from 

 3-6 cm. in diameter, is often ver}' irregular in outline and leads vertically or 

 somewhat obliquely downward into a gallery of the same diameter. The 

 large size of the opening is evidently an adaptation for two very different 

 purposes, fir.st, for enabling the ants to carry in their pieces of leaves more 



