758 THE NATURALIST ON TTTE RIVER AMAZONS. 



posed. It may be said, therefore, that on stick, and so made tubes similar to those A 

 these expanded membranes nature writes, as caddice- worms ; others (Saecophora) chose 

 on a tablet, the story of the modifications of leaves for the same purpose, forming wit a 

 species, so truly do all changes of the organi- them an elongated bag o^en at both ends,, 

 zation register themselves thereon. More- and having the inside lined with a thick web. 

 over, the same color-patterns of the wings The tubes of full-grown caterpillars of Sac- 

 generally show, with great regularity, the cophora are two inches in length, and it is at 

 degrees of blood relationship of the species, this stage of growth that I nave generally 

 As the laws of nature must be the same for seen them. They feed on the leaves of 

 all beings, the conclusions furnished by this Melastomae, and as in crawling the weight 

 group of insects must be applicable to the of so large a dwelling would be greater than 

 whole organic world ; therefore the study of the contained caterpillar could sustain, the 

 butterflies creatures selected as the types of insect attaches the case, by one or more 

 airiness and frivolity instead of being threads, to the leaves or twigs near which it 

 despised, will some day be valued as one of is feeding. 

 the most important branches of biological 



science. Foraging Ants. Many con fused statemen t s- 



Before proceeding to describe the ants, a have been published in books of travel ami 

 few remarks may be made on the singular copied in natural history works regarding; 

 cases and cocoons woven by the caterpillars these ants, which appear to have been con- 

 t>f certain moths found at Ega. The first founded with the Satiba, a sketch of whose- 

 that may be mentioned is one of the most habits has been given in the first chapter of 

 beautiful examples of insect workmanship I this work. The Saliba is a vegetable feeder, 

 ever saw. It is a cocoon, about the size of and does not attack other animals ; the ac- 

 u sparrow's egg, woven b\ r a caterpillar in counts that have been published regarding 

 broad meshes of either buff or rose -colored carnivorous ants which hunt in vast armies, 

 silk, and is frequently seen in the narrow exciting terror wherever they go, apply only- 

 alleys of the forest, suspended from the ex- to the Ecitous, or foraging ants, a totally dif- 

 tremti tip of an outstanding leaf by a strong flerent group of this tribe of insects. Th& 

 silken thread five or sU inches in length, it Ecitons are called Tauoca by the Indians, 

 forms a very conspicuous object, hanging ^ho are always on the lookout for their 

 thus in mid-air. The glossy threads with armies when they traverse the forest, so as 

 which it is knitted are stout, and the structure to avoid being attacked. I met with ten dis- 

 Is therefore not liable 10 be torn by the beaks tinct species of them, nearly all of which 

 of insectivorous birds, while its pendulous have a different system of marching ; eight 

 position makes it doubly secure against their were new to science when I sent them to- 

 attacks, the apparatus giving way when they England. Some are found commonly in- 

 peck at it. There is a smaFl orifice at each every part of the country, and one is peculiar 

 end of the egg-shaped bag, to admit of the to the open campos of Santarem ; but. a* 

 sscape ot the moth when it changes from the nearly all the species are found together at 

 little chrysalis which sleeps tranquilly in its Ega, where the forest swarmed with their 

 any cage. The moth is of a dull slaty color, armies, I have left an account of the habits 

 and belongs to the Lithosiide groupe of the / the whole genus for this part of my narra* 

 Bilk-worm family (Bombycida). When the tive. The Ecitons resemble in their habits 

 caterpillar begins its work, it lets itself down the Driver ants of tropical Africa ; but they 

 from the tip of the leaf which it has chosen, have no close relationship with them hi 

 by spinning a thread of silk, the thickness of structure, and indeed belong to quite another 

 which it slowly increases as it descends, sub-group of the ant tribe. 

 Having given the proper length to the cord, Like many other ants, the communities of 

 it proceeds to weave its elegant bag, placing Ecitons are composed, besides males aad fe- 

 itself in the centre and spinning ring's of silk males, of two classes of workers, a large- 

 at regular intervals, connecting them at the headed (worker-major) and a small-headed 

 same time, by means of cross-threads ; so that (worker-minor) class ; the large-heads have- 

 the whole, when finished, forms a loose web, in some species greatly lengthened jaws, the* 

 with quadrangular meshes of nearly equal small-heads have jaws always of the ordinary 

 size throughout. The task occupies about shape ; but the two classes are not sharpjy 

 four days. When finished, the enclosed cater- defined in structure and function, except ir* 

 pillar becomes sluggish, its skin shrivels and two of the species. There is in all of them 

 cracks, and there then remains a motionless little difference among the workers repaid 

 chrysalis of narrow shape, leaning against ing the size of the head ; but in some species 

 the sides of its silken cage. this is mot sufficient to cause a separation 



Many other kinds are found at Ega be- into classes, with division of labor ; in others 

 longing to the same cocoon-weuving family, the jaws are so monstrously lengthened in 

 ome of which differ from the res>t in then the worker-majors, that they are incapaci- 

 caterpillars possessing the art of fabricating tated for taking-part in the labors which the 

 cases with fragments of wood or leaves, in worker- minors perform ; and again, ia 

 which they lije secure from all enemies while others the difference is so great that" the dis,- 

 they are feeding and growing. I saw manj tinction of classes becomes complete, one 

 species of these ; some of them knitted to- .cling the part of soldiers, and the other that 

 fether, with fine silken threads, small bils^^.J. -workers. The peculiar featuie in th* 



