Chap. Y. 
FORAGING ANTS. 
351 
exciting terror wherever they go, apply only to the 
Ecitons, or foraging ants, a totally different group of this 
tribe of insects. The Ecitons are called Tauoca by the 
Indians, who are always on the look-out for their armies 
when they traverse the forest, so as to avoid being at- 
tacked. I met with ten distinct species of them, nearly 
all of which have a different system of marching ; eight 
were new to science when I sent them to England. Some 
are found commonly in every part of the country, and 
one is peculiar to the open campos of Santarem ; but, as 
nearly all the species are found together at Ega, where 
the forest swarmed with their armies, I have left an 
account of the habits of the whole genus for this part 
of my narrative. The Ecitons resemble, in their habits, 
the Driver-ants of Tropical Africa ; but they have no 
close relationship with them in structure, and indeed 
belong to quite another sub-group of the ant-tribe. 
Like many other ants, the communities of Ecitons 
are composed, besides males and females, of two classes 
of workers, a large-headed (worker-major) and a small- 
headed (worker-minor) class ; the large-heads have, in 
some species, greatly lengthened jaws, the small-heads 
have jaws always of the ordinary shape ; but the two 
classes are not sharply-defined in structure and function, 
except in two of the species. There is, in all of them 
a little difference amongst the workers regarding the size 
of the head ; but in some species (E. legionis) this is not 
sufficient to cause a separation into classes, with division 
of labour; in others (E. hamata) the jaws are so mon- 
strously lengthened in the worker-majors, that they are 
incapacitated from taking part in the labours which the 
