THE HARVESTING ANTS. 



281 



large yellow spot at its base. It stalks about very slowly and is quite 

 unable to sting, but instead endeavors to defend itself with the milk- 

 white, faintly odorous secretion of its anal glands. Though the colo- 

 nies are rather populous, the workers forage singly. They carry one 

 another like the species of Leptotlwra.r, the deported ant being held by 

 the mandibles while curling her body up over the head of her carrier. 

 The nests (Fig. 156) are so large and made of such rough materials that 

 one can hardly believe that they can be the work of such frail insects. 



FIG. 1 60. Disk of Pogonomyrmex rugosits, showing one of the paths extending 

 off towards the upper right-hand corner of the figure. A partial ring of chaff and 

 rejected seeds is seen to the left of the 'entrance. (Original.) 



They are huge craters from 60 cm. to 2 m. in diameter and from .2O-.5O 

 cm. in height, built of coarse desert soil intermingled with large pebbles 

 sometimes 2 cm. in diameter. The center of the crater is funnel-shaped, 

 with a great entrance of irregular outline frequently as much as 5-8 

 cm. across. The galleries and chambers are proportionally large and 

 excavated in such hard soil and to such a depth that I have never been 

 able to explore them satisfactorily. Although these nests bear a cer- 

 tain resemblance, on a large scale, to those of Messor pcrgandci, they 

 seem even more like the work of some desert rodent or reptile. /. 

 albisctosits is a smaller and more opaque species, covered with abun- 

 dant, very coarse, white, hairs. Its nests resemble those of cockerelli. 



