14 
Psyche 
[February 
that this last was what he had seen, but Viehmeyer seems to 
have interpreted the two forays which he discovered as true 
raids. Moreover each found mixed colonies which contained 
slaves of both L. acervorum and L. muscorum. Since the pos- 
sibility that such colonies could have been formed by dispossess- 
ion is very remote, these investigators concluded that FI. sub- 
Icevis must make dulotic raids. It is gratifying to be able to 
supplement their observations with others on the dulosis of FI. 
americanus. 
The slave raids of Harpagoxenus show none of the organ- 
ization and spirit so characteristic of those of Polyergus. They 
fall far short even of the lesser degree of cooperation exhibited 
by F. sanguinea. Nevertheless they are of great interest, since 
they appear to be the last manifestation of a vanishing character. 
They show the decay of dulosis and foreshadow a state of abject 
parasitism. During the progress of a raid the Harpagoxenus 
workers and their slaves cluster about the entrance of their nest 
in a manner suggestive of Polyergus, but with this the similarity 
ends. There is no rapidly moving phalanx of raiders, no con- 
centration about the entrance of the raided nest, no frantic 
activity to enlarge the entrance. The Harpagoxenus leave their 
nest singly and amble awkwardly and uncertainly to the nest 
of their victims. Only once did I see more than one Harpagox- 
enus leave the nest at the same time. On one occasion a 
column of three departed for the Leptothorax nest. However, 
this column broke up almost at once and was, I believe, purely 
fortuitous. On arriving at the Leptothorax next the Harpago- 
xenus wastes no time in preliminaries but enters at once. Having 
secured a larva or pupa it emerges as quietly as it entered and 
returns with its burden to its own nest. Quite often they lose 
their way and I have seen a number of them captured by small 
spiders while raiding. The action of Harpagoxenus after it 
enters the raided nest could not, of course, be followed in the 
field. However, observation of ants in artificial nests show that 
the brood is obtained by force and not by stealth, although 
indeed, the action of the Leptothorax during a raid furnishes 
ample evidence that this is the case. 
The nest which yielded most of the observations on the 
