50 
Psyche 
[June 
insect, it follows that the head of the Colobopsis major 
can be thrust into close-fitting apertures without putting 
the rest of the insect into an impossible posture. 
We may now consider the method by which minors of 
texanus are admitted to the nest. When the guarding major 
has assumed the phragmotic position the lower rim of the 
head usually projects slightly beyond the edge of the nest 
entrance. The antennae are held at either side of the 
cephalic disc and are clearly visible from the outside. The 
returning minor may or may not touch the antennae of the 
guard, although it usually does so. Thereafter the guard 
crouches down. This brings the anterior rim of the head 
below the level of the fioor of the passage or, if the guard 
stands completely inside the passage, the front of the head 
is raised as the guard crouches. The dorsum of the guard’s 
thorax is now no longer close to the roof of the passage 
and the minor can, if it is sufficiently active, wriggle be- 
tween the dorsum of the thorax and the roof of the pass- 
age. This action is seldom completed without considerable 
struggle on the part of the entering minor and at times 
the major will cease to crouch before the minor has gone 
through and pin the minor between its thoracic dorsum 
and the roof of the passage. The senior author has seen 
minors thus trapped who, perforce, remained in this awk- 
ward position for several minutes until the major would 
crouch again and release them. If the passageways are 
made large enough to accomodate two majors simultaneous- 
ly, they ordinarily assume a position where they are back 
to back. Under such circumstances the two opposed ceph- 
alic discs form a V-shaped area. The bottom of this V is 
open but the space behind it is closed by the closely ap- 
proximated thoracic dorsi of the two guards. When minors 
are admitted to the nest both majors crouch and the enter- 
ing worker struggles through the narrow space between 
the thoraces of the guards. It seems scarcely necessary to 
state that there is no part of this behavior which at all 
resembles that of the Colobopsis major, which must back 
away from the nest entrance to admit the returning minor. 
Explanation of Plate 4 
Cryptocei'Uf^ texanusi, dorsal view of dealated female. 
