522 THE AMERICAN NATURALIST. [Vor. XXXV. 
fyramicus to Pogonomyrmex barbatus. Though the former 
ant, which ranges from Colorado and North Carolina to the 
Argentine Republic, is not uncommon at Austin, I have 
not often observed it in this locality. But I have found its 
small earthen mounds in very great numbers about Aguas 
Calientes in Mexico. Here it occurs quite as frequently out- 
side as within the formicary boundaries, both of the typical 
P. barbatus and its variety, molifactens. Like Forelius,’ 
Dorymyrmex is an ant of the barren soil, and its occurrence 
within the formicary precincts of the agriculturals is probably 
open to the same explanation. It is, however, far more pug- 
nacious than Forelius, and, though tolerated by Pogonomyrmex, 
it resents any intrusion on the part of its larger neighbors. 
Both Forelius and Dorymyrmex, like many other dolichoderines, 
emit a rank secretion, which is in all probability protective. 
6. Dorymyrmex pyramicus Roger, var. flavus McCook. 
According to McCook (82, pp. 155—158), this variety occurs 
with Pogonomyrmex occidentalis Cresson in Colorado. ‘ There 
was scarcely a formicary which came under observation, from 
first to last, that had not upon the clearing one or more colo- 
nies of the erratic ant, Dorymyrmex insanus Buckley, or a new 
species of variety, D. favus McCook. Usually there are two 
or three nests, sometimes four, located upon different parts of 
the pavement. These are small moundlets of fine soil, sur- 
rounding a central opening which leads into an irregular series 
of galleries and chambers. The same insects are parasitic 
upon the disks of the agricultural ants of Texas, and exhibit 
there characteristics similar to those in the Garden of the 
Gods. They are small, very active, irritable, intensely pugna 
cious, and courageous to the last degree. The manner in which 
these little fellows bullied and badgered their occident hosts 
was amusing, and indeed amazing.” Nests of Dorymyrmex 
pyramicus, var. flavus, are rather common at Austin, but as ye 
I have failed to find them within the Pogonomyrmex formi- 
caries, although I have no doubt that they occasionally occur 
in such situations. 
