of Exotic Hymcnoptera. OT 



Tlie species of the geuiis Eciton are very abundant, and cannot 

 fail to attract general attention ; we are now acquainted with about 

 twenty species. The processions of these insects are of common 

 occurrence ; and the different colours of the species are very obser- 

 vable when the lines are seen upon the march, some, as Mr. Bates 

 remarks, appealing like '' a liquid stream of metal." These Ants 

 are regular clearers of aU animal matter, living or dead : when on 

 a foraging expedition, they spread out their columns, climbing over 

 every leaf, plant, shrub, and tree, putting the whole animal as well 

 as insect world into commotion and alarm ; should any decaying 

 mass of vegetable matter fall in their way, it is instantly covered 

 with a living crowd, every chink and cranny is carefully searched, 

 after which the army resumes its march. All apterous insects, par- 

 ticularly BJattcv and Spiders (the former being exceedingly nume- 

 rous under fallen leaves, especially in their larva state), are preyed 

 upon ; the larvae of Lepidoptera and Diptera fall an easy prey, as 

 well as the species of Formicida'. At other times a commimity of 

 Ecitons engage in a regular attack upon a nest of some peaceful and 

 industrious species of Fovmica ; the Ecitons crowd into the nest of 

 the ants, each seizing upon a helpless victim, and carry or drag it 

 out of the nest ; if the ant prove too bulky for a single Eciton to 

 carry, it is ruthlessly torn into pieces, two or more assisting in the 

 operation. The march is then commenced back to the nest of the 

 Ecitons, the living ants and the mangled remains of others being 

 probably conveyed there for the purpose of feeding the young brood 

 of the mai'auders. 



Every community of Eciton consists of two distinct forms of 

 workers, besides the males and females. In the typical species, E. lin- 

 mata, the large worker, or soldier, is furnished with long, curved, 

 sickle-shaped mandibles ; there is no gradation either in the form 

 of these organs, or between these larger ants and the ordinary 

 smaller workers : these soldiers bear the proportion of about five to 

 one hundred of the smaller individuals. In other species, such as 

 E. vastator and E. erratica. dosciibed in the present paper, the 

 soldier workers have the head greatly enlarged, vrith mandibles of the 

 ordinary size ; but even here there Ls no trace of gradation between 

 the two forms : it is true that the smaller form has individuals 

 differing in size ; so also, but in a less degree, do the big-headed 

 soldiers differ in size ; but between the two distinct forms there are 

 no gradations which would unite them. 



Although the ants belonging to this genus are so numerous in 

 Brazil that they cannot fail to attract the notice of the natiiralist, 



f2 



