74 
Psyche 
[June 
For it is more than thirty -two hundred feet below the next 
lowest record for huachucanus. The situation and character 
of the Needles nest were both unusual for a colony of 
huachucanus. Dr. Cole described it as “ a rather minute 
crater mound in sand.” It has been shown above that 
huachucanus nests in gravelly soil and only rarely con- 
structs a crater. Since everything about the Needles record 
is wrong for huachucanus, I wrote Dr. Cole for permission 
to examine the specimens on which it is based. Unfor- 
tunately, they have been lost. There is, therefore, no pos- 
sibility of a further check on this highly unusual record. 
In my opinion it is best disregarded. It is very unlikely 
that the ant was actually huachucanus and the inclusion of 
the Needles record obscures the beautifully clear distribu- 
tional picture which is shown by every other record for 
huachucanus. 
For all the other records for this species indicate that 
huachucanus is a member of the Upper Sonoran ant fauna. 
Many of the records are from mountainous areas and, 
when the insect occurs in such regions it prefers foothill 
canyons as nesting sites. It is equally at home, however, 
on the grassy, elevated plains at the base of the mountains. 
But it does not occur in nearby areas of less elevation where 
Lower Sonoran species are encountered. It is interesting 
to note that, at the eastern end of its range, huachucanus 
occurs in stations where P. occidentalis and the typical 
P. barbatus are also present. The main range of the typical 
barbatus lies in Mexico. That of occidentalis lies entirely 
to the north of it as far as is known at present. Hence 
there is only a limited area in parts of Arizona and New 
Mexico where these two species occur in close proximity. 
For the most part the range of huachucanus follows this 
area of overlap with remarkable exactness. The most ob- 
vious explanation for the distribution of huachucanus 
would, therefore, assume an unusually narrow tolerance for 
temperature on the part of this species. Such a limitation 
would exclude huachucanus from northern regions occupied 
by occidentalis and at the same time debar it from southern 
areas utilized by the typical barbatus. If this explanation 
is correct, then huachucanus shows less environmental 
adaptability than is usually the case with members of the 
