758 BuUctin American Museum of Natttnil History. ["\'ol. XXIII, 



ever, that these nests were more than a meter deep. That T. furrifrx 

 requires rather moist soil is also shown by a peeuliarity of its nests in the 

 post-oak regions. Here, as I have said, the subsoil is red elay overlaid with 

 a drver, and more porous blaek earth. The ants not only carry their ex- 

 cavations down into the subsoil but carefully line the galleries and chambers 

 in the black soil, to the very orifice of the turret, with a thin layer of clay 

 brought up from below. Thus the nest becomes a bottle with thin clay walls, 

 alternately constricted into slender tubes (the galleries) and dilated into 

 ampulliform enlargements (the chambers). This clay lining is probably 

 a very efficient means of preventing both the escape of the moistiu'e from the 

 chambers during dry spells and the entrance during rainy Aveather of too 

 much moisture from the soil. Unlike the nests of scpfcntrioualis, those of 

 fiirrifex are not closed during the dry season. Such closure is in fact un- 

 necessary because the nests are considerably deeper, situated in soil which 

 retains the moisture much longer, and have very small orifices. 



The first chamber, like that of the .sepfentrionaUs nest, is used as a work- 

 shop and temporary repository for fresh and discarded vegetable substances. 

 The rootlets of plants are also left dangling into the remaining chambers 

 as a suspensorium for the fungus gardens. These resemble the gardens of 

 scpfenirionalis but are smaller, v>-hiter, and of a more delicate texture, as if 

 the vegetable substratum on which they were groAvn had been more finely 

 comminuted. In the confection of this substratum the same materials are 

 used, viz., the withered catkins of oaks, the scales of buds, bits of dead leaves 

 and the excrement of caterpillars. I have never seen these ants cutting or 

 bringing in green leaves of any description. At INIarfa and Ft. Stockton 

 they were collecting the withered florets of a small yellow composite {Pedis 

 ieneUci). The nest openings were often surrounded by a circlet of these 

 florets, so that to one riding over the desert each nest seemed to be marked 

 by a small handful of saffron. All of the vegetable substances are jiicked 

 up by the ants from the ground and not collected directly from the plants, 

 as iurrijex is even less inclined than septentrionctlis to climb about on the 

 vegetation. The microscopic structure of the fungus gardens is very much 

 like that of sepientrionalis. The hyphre measure .78 /( in diameter; the 

 bromatia .3-. 4 mm. and consist of beautifully developed gongylidia 3.5-4.7 fi 

 in length and somewhat less in breadth. 



The dealated females of iurrijex take part in excavating and foraging, 

 like the workers. On one occasion, early in the morning of June 14, in the 

 midst of the desert at ^larfa, I came upon a whole colony of this ant, com- 

 prising some thirty workers and five dealated females, in the act of digging 

 a nest in the hard adobe soil. They had evidently been compelled to for- 

 sake their old nest during the night on account of the drought, which was 



