(hap. V. 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 



