FIVE KINDS OF INDIVIDUALS IN SAUBA. 21 
and watching for approaching danger. They would 
occasionally drop their bodies to the ground again, run 
off to one side, and fiercely work their jaws and antenne, 
as if having detected some strange sounds in the dis- 
tance. Discerning nothing, they would quickly return 
to their posts and resume their positions, thus acting 
as scouts.’! 
The same thing has been noticed by other natu- 
ralists. Bates, for instance, states that in the marching 
columns of Eciton drepanophora the large-headed 
workers ‘all trotted along empty-handed and outside 
the column, at pretty regular intervals from each other, 
like subaltern officers in a marching regiment... . I 
did not see them change their position, or take any 
notice of their small-headed comrades;’ and he says 
that if the column was disturbed they appeared less 
pugunacious than the others. 
In other species, however, of the same genus, Eciton 
vastator and E. erratica, which also have two distinct 
kinds of workers, the ones with large heads do appear 
to act mainly as soldiers. When a breach is made in 
one of their covered ways, the small workers set to 
work to repair the damage, while the large-headed ones 
issue forth in a menacing manner, rearing themselves. 
up and threatening with their jaws. 
In the Sauba Ant of South America (dcodoma 
cephalotes), the complexity is carried still further; 
1 Rev. T. &. Savage on the ‘Habits of the Driver Ants,’ Trans 
Ent. Soc., vol v. p. 12. 
