1911] Wheeler — Tim Fungus-Growing Ants from Arizona 95 



a trace of a median longitudinal impression at the anterior end. Legs long and 

 rather slender. 



Mandibles and clypeal border shining, the former finely striated. Remainder 

 of body opaque and finely granular or very finely punctate-rugulose. The various 

 ridges, spines and protuberances, the front, the posterior corners and occiput of the 

 head, the thoracic dorsum and pleurie (except in the mid-dorsal line between the 

 protuberances), the upper-surface of the petiole, post-petiole (except its concave 

 dorsal surface), and gaster beset with small but prominent and rather acute tuber- 

 cles. Legs, scapes and cheeks beset with similar but smaller and much less promi- 

 nent elevations. 



Hairs and pubescence fulvous, the former hooked, erect and rather uniformly 

 distributed over the body, legs and scapes; the pubescence is very short and delicate 

 and present only on the antennal scapes. 



Body ferruginous red; legs and antennae a shade paler; borders of mandibles 

 black; frontal area, vertex and occiput each often with a black or dark brown spot. 

 Old specimens not infrequently have the body covered with a bluish bloom. 



Described from numerous specimens taken Nov. 10-16, 1910 

 from several colonies in Miller and Hunter Canyons, Huachuca 

 Mts., Arizona at elevations varying from 5000 to 6000 ft. 



T. arizonensis is most closely related to T. saussurei Forel but 

 differs from this species and from T. septentrionalis in its larger 

 average size, much deeper color, longer antennal scapes, more 

 numerous and more acute tubercles, especially on the posterior por- 

 tions of the head and upper surface of the gaster, the less rounded 

 sides of the head, the stouter and more backwardly directed 

 epinotal spines and the erect, instead of reclinate, hairs on the legs 

 and antennal scapes. From T. turrifex, arizonensis differs in its 

 much larger size, much longer antennal scapes, more backwardly 

 directed epinotal spines and proportionally narrower postpetiole. 

 In turrifex, moreover, the mesoepinotal constriction is more pro- 

 nounced, the epinotal declivity is not sloping but vertical, the 

 inferior pronotal spines are acute, there is a prominent median 

 pronotal tubercle and the dorsal surface of the postpetiole is beset 

 posteriorly with small tubercles and is flattened but not concave. 



The territory in which T. arizonensis was observed would seem 

 at first sight to be very unfavorable to an ant addicted to cultivat- 

 ing fungi for food, and is certainly very different from that inhabited 

 by T. septentrionalis and turrifex. T. septentrionalis flourishes only 

 in the sandy oak woods of the Mississippi Valley, Atlantic and 

 Gulf States as far north as southern Illinois and southern New 

 Jersey; while T. turrifex prefers the black or argillaceous soil of 



