AMERICAN UYMENOPTERA. 257 



base. 'PI. V again shows the development of two hills of nearly 

 equal size side by side. The same feature is shown at PI. VI, although 

 in that group the hills have blended. 



All this shows a fixed habit in the growth of the hills. As the 

 community increases, new cones are begun, the opening of some 

 gallery perhaps being taken as the centre ©f operations. I have 

 frequently observed these embryo hills. The commencement of a hill 

 sometimes depends upon the location of the feeding ground. Eight 

 rods from the large hill in PI. II is an oak tree, which was covered 

 with aphides, and upon which the inhabitants of that republic have 

 established a permanent foraging ground. About a foot from the 

 base of the tree an embryo hill has been begun by a portion of these 

 workers. I observed them closely and have no hesitation in identify- 

 ing them as of the one family. A number of hills, some of them 

 of goodly size, which are built up against the trunks of trees, have 

 evidently been formed in the same way. Indeed it is highly probable, 

 from observations hereafter recorded, that most if not all the hills have 

 similar connection with the trees which furnish the feeding grounds, 

 by underground galleries. 



What influence the annual flitting of the males and females, and 

 the chance settlement of the latter after fertilization, may have upon 

 the formation of new hills, I am not able to say, as I have not been 

 so fortunate as to witness a swarming. Some of the fruitful females, 

 it is known, are seized by the workers upon the mounds and others 

 upon the neighboring grass stalks and weeds, and are thence forced 

 into the hill, liut there must be some who drop upon secluded spots, 

 and unobserved, begin measures for the establishment of new families, 

 according to their instinct. These families eventually erect independent 

 hills, which in turn become the mother hills of new hill-clusters. Thus 

 ant colonies, like some groves and forests, grow from the parent stock 

 by "shoots." In some cases, it may be added, there is a small aban- 

 doned moss covered mound which seems to have been the original 

 Capitol of the republic. But like many a now deserted and grass 

 grown village of human inhabitants, formerly the seat of flourishing 

 and active traffic, the tide of fortune has swept away from the once 

 thronged galleries, and busy communities in vastly increased propor- 

 tions, have sprung up around the original settlement. 



Building ^alerials.— The materials composing an ant hill are 

 various, although the sandy soil forms well-nigh the entire bulk thereof. 

 This soil, so far as I observed, is always brought from the interior of 



