1951] 
Creighton — Arizona Ants 
53 
from colonies in which the female was not secured. Only 
one of these three colonies represented the majority of the 
nest. In this colony there were ten majors. Three of these 
majors have no trace of ulcers on the cheeks. Six of them 
have very shallow ulcers which are, nevertheless, covered 
with very coarse rugae. These rugae tend to obscure the 
ulcers but each depression has a low, distinct, lateral ridge 
which bounds its outer edge. One major worker in the above 
colony has somewhat deeper ulcers, although they are not as 
deep as those of the type of ulcerosus. Both the remaining 
colonies were fragments of nests in which the passages were 
lost during the course of excavation. The first contained 
two non-ulcerate majors. The second contained two majors 
with shallow ulcers having rather feeble rugae. 
The facts just presented permit the following statements 
concerning this insect : 
1. The female of this species is normal in every respect 
and there is no correlation between the cephalic structure 
of the female and that of the major worker. 
2. The same type of female may produce widely different 
sorts of major workers. 
3. The range of variation in the head of the major worker 
extends well beyond the condition found in the type of 
ulcerosus , which stands about midway in the series of transi- 
tional forms. 
4. The full range of variation in the cephalic structure 
of the major is seldom, if ever, present in a single nest 
series. But in every nest series there is sufficient variation 
in the head of the major to make ulceration useless as a 
separatory character. 
5. The non-ulcerate majors always have low and com- 
paratively obscure rugae on their cheeks. Those with shal- 
low ulcers may have the rugae either feebly developed or 
coarse and prominent. The majors with very deep ulcers 
invariably have extremely coarse rugae on the front of the 
head. Cephalic sculpture, like the ulceration of the cheeks, 
cannot be used as a separatory character. 
There is but one conclusion to be drawn from the above 
data : ulcerosus and bruesi are the same insect. The most 
immediate effect resulting from the recognition of this fact 
