134 
Psyche 
[December 
Linares (1300-6200 feet) and in those south and west of 
Monterrey (2000-7200 feet). By this time it was apparent 
that Ps. apache prefers to nest in old live oak limbs. Many 
hundred limbs of live oaks were examined in the areas 
mentioned above. While three different species of Pseudo - 
myrmex were encountered in these limbs, none of them 
showed the slightest relation to apache. The coastal plain 
was less thoroughly studied, but collections made in the 
area between Mante and Tampico showed no trace of 
apache. The only abundant Pseudo m yrm e x in that area is 
a particularly vicious, light brown species which lives in 
the thorns of the bull-horn Acacia. In northwestern Mexico 
the situation is essentially similar. Ps. apache is abundant 
in the mountains at the northern end of the main chain 
of the Sierra Madre Occidental. But the writer failed to 
find it in several lesser ranges in northern Sonora. It may 
be added that in some of these ranges the conditions seemed 
ideal for this ant and the writer felt certain that it would 
be found. Negative evidence of this sort does not prove the 
absence of Ps. apache in the areas mentioned above, but it 
does prove that the insect is less abundant in these areas 
than in stations further north. This would not be true if 
this ant were a northern fringe of some southern species, 
for in that case its incidence should increase to the south. 
But, since all available evidence points to the fact that the 
area of greatest abundance for this ant lies in southern 
Arizona and that its incidence decreases to the south, it is 
safe to conclude that the insect is not a northern race of 
decipiens but a separate species. 
Since all three castes have been figured on the plate 
which accompanies this article, the descriptive material 
which follows is largely limited to details of sculpture and 
pilosity that could not be shown in the figures. 
Pseudomyrmex apache sp. nov. 
Plate 12 
Female: head (mandibles excluded) 1.35 mm.; thorax 
2.2 mm.; overall length 7-8 mm. 
Upper surface of the head covered with small, shallow, 
circular punctures. These punctures close set from the 
anterior margin of the head to the level of the median ocel- 
