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Psyche 
[December 
late but at the middle of the clypeus there is a heavy, medi- 
an ridge which runs from front to back. This ridge is 
wavy but it is not reticulate. 
5. In papago the portion of the clypeus behind the trunca- 
tion is not clearly set off from the frontal lobes and the 
frontal area is indistinct. In the Vera Cruz majors the 
portion of the clypeus behind the truncation is clearly 
separated from the frontal lobes and the frontal area, al- 
though small, is very distinct. 
6. In papago the serrate flange at the edge of the trunc- 
ated portion of the head is lower and less prominent than 
that of the Vera Cruz majors. 
7. In papago the erect hairs on the sides of the head are 
longer, more numerous and less clavate than those of the 
Vera Cruz majors. In both species most of the hairs on the 
mandibles and the truncated portion of the clypeus are so 
strongly clubbed that they are shaped like tear drops. It 
is strange that Wheeler made no mention of these con- 
spicuous and characteristic hairs. From a practical point 
of view they furnish the easiest means for distinguishing 
papago from any other species which occurs in the United 
States. None of our other species have such hairs, hence 
there is no possibility of confusing papago with any other 
species if these hairs are made the basis for its recognition. 
Before concluding this paper I wish to present an ac- 
count of the habits of C. papago. The ten colonies taken 
to date have all come from evergreen oaks or mesquite trees. 
The two oaks involved are Quercus emoryi and Q. oblong- 
ifolia. Most nests are constructed in the stubs of broken- 
off branches which have a diameter of an inch and a half 
or more. The thickness of the stub seems to be more im- 
portant than its length. I have taken colonies from stubs 
less than six inches long but I have yet to see one in a 
branch that was small enough to be considered a twig. 
Inside the stub are numerous, narrow passages which 
roughly parallel the grain of the wood. Several openings 
lead from these to the outside. It is evident that in a fully 
developed nest of papago there must be several “janitors” 
on duty at the same time. As mentioned above, this ant 
does not ordinarily nest in twigs. At first I supposed that 
