JAMES A. G. REHN AND MORGAN HEBARD 233 



shows considerable variation in the size ot the inclivi(Uials and in 

 the intensitj^ of the color pattern. The males from four thousand 

 feet elevation, in a distinctly more arid section, subject to more 

 intense heat and light, show the maximum recessive color type, 

 appi'oached to some extent, however, l^y several males from six 

 thousand feet. The pronotal disk shows some variation in gen- 

 eral form in both sexes, being somewhat broader in proportion in 

 some individuals than in others, but in even the broadest speci- 

 mens we find no confusing approach to A. ovatiis, while the sculp- 

 ture shows virtually no variation. In certain females the teeth 

 of the dorsal margin of the ovipositor cover less of the margin 

 than in the allotype. The sulcus of the fastigium of the vertex 

 is more extensive cephalad in some specimens than in others, 

 and in these the fastigium is distinctly emarginate cephalad when 

 seen from the dorsum. 



The distal spine on the d;)rso-cephalic margin of the cephalic 

 tibiae is occasionally absent, as is also the spine near the for 

 amina. The median tibiae occasionally have as few as a single 

 spine on the aorso-cephalic margin. The caudal femora may 

 have as few as three or as many as ten spines on the ventro- 

 external margin, and be from unarmed to having as many as 

 five spines on the ventro-internal margin. 



This species is almost entirely restricted to the tree yucca or 

 "Joshua Tree" {Clistoyucca brevijolia) belt found on the north- 

 eastern slope of the Spring or Charleston Mountains in Clark 

 County, southern Nevada. The tree yucca begins to be scatter- 

 ingly evident on the slope of the range somewhat below the four 

 thousand foot level, becoming more abundant, predominating 

 the landscape, at about four thousand five hundred feet, and giv- 

 ing way to the junipers and pinyons in the neighborhood of the 

 six thousand foot contour. Our field notes on this species are 

 as follows: ''Aglaothorax colonies found in Joshuas and in one 

 large cedar in their midst. All were found hidden at the base 

 of the dried leaves just below the green leaves, or at the bases 

 of the green leaves themselves. They occurred at heights of from 

 four to eight feet from the ground, l)ut were most abundant 

 at about five to six feet. All were nestled closely to the branch, 



TRANS. AM, ENT. SOC, XLVI. 



