94 
Psyche 
[September 
of texana coincides with that of huachucana, there would 
be ample opportunity for cross-fertilization and, if this 
occurred, the two populations would soon merge. The 
fact that the two populations show no sign of intergrada- 
tion may be taken as proof that no cross-fertilization is 
occurring. If it can be shown that the nuptial flights of the 
two species take place at different times, one need look no 
further for the mechanism which maintains the two pop- 
ulations as separate entities. The evidence on this point 
is scanty but it seems significant nonetheless. One nest of 
huachucana, secured on July 24th, contained a few mature 
males and many mature females. There were no male or 
female pupae in this nest and only a few callows of the 
sexual forms. This leads me to believe that the nuptial 
flight was about to take place. If so, the marriage flight 
of huachucana must occur at the end of July or the first 
of August. During the month of July (7th-28th) a number 
of nests of texana were examined. No winged sexual forms 
were found in any of them. Either the nuptial flight had 
taken place before July 7th or it would be some weeks before 
the sexual forms matured, in which case the flight would 
come much later in the summer. In either case the nuptial 
flight of texana would not coincide with that of huachucana. 
The descriptions of the male and female of huachucana 
which follow deal mainly with details of sculpture, pilosity 
and color. The general structural features of all three 
castes of this insect are shown in the figures on Plate 7. 
Female: length; head (exclusive of mandibles) 1.6 mm.: 
thorax 3 mm. ; total length 8-9 mm. Mandibles with fine 
and rather even longitudinal striae which spread slightly as 
they approach the masticatory margin. Clypeus and frontal 
area with slightly wavy, longitudinal rugae. Longitudinal 
rugae on the cheeks and front notably coarser and much 
more wavy. Longitudinal rugae immediately behind the 
Explanation of Plate 7 
Aphaenogaster ( Attomyrma ) huachucana Creighton. Fig. 1. Worker. 
Fig. 2. Male, wings on left side removed. Fig. 3. Female, wings on left 
side removed. (Figs. 1-3 to the same scale.) Fig. 4. Head of worker 
(drawn from type) . Fig. 5. Head of male. Fig. 6. Head of female. 
