92 
Psyche 
[September 
the 6500 foot level is very small and I feel sure that colonies 
founded above this level only rarely come to maturity. This 
rather abrupt termination of the range in the neighborhood 
of 6500 feet offers a marked contrast to the abundance of 
texana at lower levels. It should be noted that at these 
lower levels, and on the same slopes where the nests of 
texana occur, there is an extraordinarily rich ant fauna. 
Conspicuous in it are representatives of genera which are 
typically Sonoran ( Pogonomyrmex , Myrmecocystus, Xipho- 
myrmex, etc.). It is true that these Sonoran elements are 
not as abundant in the evergreen oak belt as they are on the 
plains at the base of the mountains (where texana appears 
to be absent) but they are sufficiently well represented to 
give the lower part of the evergreen oak association a 
distinctly Sonoran character. It may, therefore be stated 
that, in the Huachuca Mountains, texana is associated with 
the Sonoran elements of the biota and shows little tendency 
to nest outside the area where the Sonoran representatives 
occur. 
The association where huachucana is found is a wholly 
different one. This is Shreve’s “northern mesic evergreen 
forest”. This association occurs in various parts of Arizona 
and because its constituent plants vary somewhat with 
latitude, it is more difficult to characterize than is the 
evergreen oak association. In the Huachuca Mountains 
the northern mesic evergreen forest is predominantly a 
zone of pines. As noted above the lower edge of this pine 
belt mingles with the upper edge of the evergreen oak belt. 
At the 7000 foot level on the northeastern slopes the pines 
are the dominant element of the flora. At the 8000 foot 
level the stand of pine is frequently interrupted by aspen 
groves. These groves continue to the tops of the peaks 
but do not form a belt. According to Shreve the pines may 
be renlaced by spruce and fir at elevations above 9000 feet. 
If this is true in the Huachucas the spruces and firs must 
be limited to a small area at the top of Miller Peak and 
Carr Peak, The five nests of huachucana which were 
found during the summer of 1950 were all situated between 
the 7000 and 8000 foot levels. The area in which they 
occurred lay between the head of Carr Canyon and the 
