172 
Psyche 
[December 
they may be too large to take into the nest without dissection. The 
majors are very efficient at this for they have powerful mandibles and 
use them effectively. But their main function seems to be to guard 
the nest entrance. They stand so close to the nest entrance that it is 
often possible to see them and they savagely attack any object thrust 
into the nest entrance. This attack consists of locking the jaws on the 
intruding object and the major will often hold on so firmly that it 
can be pulled out of the nest. It appears that a cluster of majors is 
normally present just inside the nest entrance and it is easy to ap- 
preciate why this would make the nest virtually impregnable to any 
intruder. For, since the walls of the nest are solid rock, the guarding 
majors cannot be outflanked. 
Despite the fact that the minors of clydei occasionally bring in 
living victims I believe that this species is best regarded as a scaven- 
ger. This view is based on the lack of pugnacity in the minor. Ex- 
periments with this caste in artificial nests showed that the minor of 
clydei is slow to attack other insects and equally slow to defend itself 
when attacked by them. Since I had observed foraging minors of 
clydei entering termite passages it was a surprise to find that when 
termites were introduced into the artificial nests they usually killed 
the minors of clydei even when the latter outnumbered them. It 
seems safe to assume that most of the termites or termite remains 
brought back to the nests of clydei are dead or moribund individuals 
secured by stealth rather than by predation. This behavior is entirely 
unlike that of the species of Pheidole which are carnivorous and pred- 
atory. Dr. Gregg and I have shown (3) that Ph. titanis , which 
conducts well-organized forays against termite nests, has a minor 
that is fully as pugnacious as the major. Both castes participate in 
the foray and, when this is successful, both castes return to their nest 
with live termites in their jaws. 
In conclusion I wish to point out a suggestive feature in the 
response of clydei to elevation. The insect is now known from five 
stations. These show little latitudinal difference since all five occur 
in an east-west band less than a hundred miles wide of which Lat. 
33° is the approximate center. Yet the elevational range shown by 
these five stations is striking. It is given below: 
STATION 
Carizozo, New Mexico 
Windy Point, Sta. Catalina Mts., Ariz. 
Horse Tanks, Castle Dome Mts., Ariz. 
Deep Canyon, Sta. Rosa Mts., Calif. 
Split Mountain, Anza Desert, Calif. 
ELEVATION 
5429 feet 
7100 feet 
1200 feet 
1200 feet 
500 feet 
It may be added that clydei is not confined to the 1200 foot level 
