iv SOCIAL HOMES 135 



that the gleanings are minutely subdivided and stored in 

 the formic chambers until decayed. On the rotten mass 

 grows a minute white fungus on which the ants feed ; 

 they are in fact mushroom growers and eaters. 



Great interest is attached to certain mason ants 

 of the New World, the so-called Agricultural 

 Ants of Texas and Florida and the Occident 

 Ants of the American plains. The formicaries of 

 Pogonomyrmex barbatus are scattered over the light 





FIG. 21. View of the nest of a Provident Ant (Atta barbara) from Mentone 

 showing a granary excavated in rock and the conical refuse heap. 



soil on the hill slopes of Texas, in the deep dark earth 

 of the highlands and valleys, among the rocks, indeed 

 almost everywhere. Externally they are for the most 

 part flat, smooth, circular disks in the midst of sur- 

 rounding herbage, presenting the appearance of minia- 

 ture " clearings " in the American backwoods (see Fig. 

 1 8).. Some of them are as large as from seven to twelve 

 feet in diameter, the average ones reach a diameter of 

 only four or five feet, covering a space of from twenty- 



