44 
Psyche 
[June 
Two facts are shown by the above figures. The colonies 
of texanus are always small and they are often pleometro- 
tic. It may be stated that most of the above colonies came 
from separate trees. The chance that a colony of texanus 
may be polydomus was constantly kept in mind. Hence 
colonies taken in closely adjacent limbs or at separated 
intervals in the same limb were treated as parts of a single 
nest. It may be, therefore, that the relatively large totals 
in colonies 9 and 12 represent more than a single colony. 
The outstanding point of interest in the biology of 
texanus is the possibility that the major may serve in a 
phragmotic capacity. A good deal of what has been said on 
this subject seems to have been published without much 
idea of certain structural features which are involved. In 
order to make these features clear the junior author has 
prepared figures of the female, major and minor of Cryp- 
tocerus texanus (Pis. 3 and 4; text-figs. 1 and 2). Refer- 
ence to these figures will show that the prominent cephalic 
disc present in the female and major of texanus, does not 
cover all of the upper surface of the head. Projecting rear- 
ward beyond this disc are two conspicuous occipital angles. 
Although these angles lie below the level of the rim of the 
disc they cannot be disregarded for they, and not the 
rounded posterior rim of the cephalic disc, determine the 
size of the aperture into which the head can be thrust. 
Behind these occipital angles stand the even more prom- 
inent humeral angles of the thorax. In the figure of the 
major considerations of perspective have made it neces- 
sary to show these angles as wider than the head, for the 
latter lies below and in front of them. But, even disre- 
garding the matter of perspective, the maximum width of 
the dorsum of the thorax at the humeral angles equals or 
slightly exceeds the maximum diameter of the cephalic disc. 
It follows that the thorax of the major and the female of 
texanus (at least at the humeri) is fully as wide as the 
head and often a little wider than the head. It further 
follows that the diameter of a passage which the texanus 
major can occlude is determined as much by the width of 
the prothorax as it is by the size and shape of the cephalic 
disc. The failure of previous investigators to grasp this 
fact has been the cause of confusion in the past. 
