1952] 
Creighton — Pseudomyrmex apache 
139 
scence fine and obscure, very dilute on the head, more 
abundant on the thorax, petiolar nodes and gaster, but 
nowhere conspicuous. 
Color: uniform, clear, golden yellow. In some specimens 
the posterior gastric segment is slightly infuscated. 
Types of female, male and worker deposited in the col- 
lection of the Museum of Comparative Zoology, Cambridge, 
Mass.; the type locality is Brown Canyon (4400'), Baboqui- 
vari Mts., Arizona. Type nest taken on Sept. 2, 1951, in 
Quercus oblongifolia. 
Because of its clear, yellow color and dilute pubescence 
apache is not likely to be confused with any of our other 
species except pallida. There is little likelihood of confusion 
between these two species if all castes are present, for 
apache is larger than pallida and this difference is partic- 
ularly striking in the sexual forms. Workers from young 
nests of apache are, however, sometimes no larger than 
those of pallida. In such cases recognition depends upon 
other criteria which will separate the two species regard- 
less of size. Thus the worker of apache is more heavily 
sculptured than that of pallida , particularly on the upper 
surface of the head. In apache the cephalic punctures and 
the delicate, coriaceous sculpture between them can be 
readily seen, even under medium magnification, and the 
surface of the head is feebly shining. In pallida the cephalic 
sculpture is notably finer. The punctures are scarcely dis- 
tinguishable from the sculpture between them, even under 
high magnification, and the surface of the head is moder- 
ately shining. The head of apache is broader in proportion 
to its length, with the sides more convex than is the case 
with pallida. The greatest length of the eye in apache is 
slightly less than one half the distance from the insertion 
of the mandible to the occipital margin. In , pallida the 
greatest length of the eye is slightly more than one half 
the above distance. The petiolar node of apache, seen in 
profile has a broadly rounded crest, from which both the 
anterior and the posterior face slope away at about the 
same angle. Thus the outline of the node appears as a 
flattened and slightly lopsided arc. In pallida the rear face 
of the node of the petiole descends much more abruptly 
