The next day, the 24th, began with a long ride on horseback before breakfast, after which I accompanied Mr. Agassiz on a sort of exploration among the Cupim nests (the nests of the Termites). These are mounds sometimes three or four or even six feet high, and from two to three or four feet in diameter, of an extraordinary solidity, almost as hard as rock. Senhor Lage sent with us several negroes carrying axes to split them open, which, with all their strength, proved no easy task. These nests appear usually to have been built around some old trunk or root as a foundation; the interior, with its endless serpentine passages, looked not unlike the convolutions of a meandrina or brain coral; the walls of the passages seemed to be built of earth that had been chewed or kneaded in some way, giving them somewhat the consistency of paper. The interior was quite soft and brittle, so that as soon as the negroes could break through the outer envelope, about six inches in thickness, the whole structure readily fell to pieces. It had no opening outside, but we found, on uprooting one of these edifices from the bottom, that the whole base was perforated with holes leading into the ground beneath. The interior of all of them swarmed with the different kinds of inhabitants; the little white ones, the larger black ones with brown heads and powerful forceps, and in each were found one or two very large swollen white ones, quite different in dimensions and appearance from the rest, probably the queens. With the assistance of the negroes, Mr. Agassiz made, for future examination, a large collection of all the different kinds of individuals thus living together in various numeric proportions, and he would gladly have carried away one of the nests, but they are too cumbersome for transportation. The Cupim nests are very different from the dwellings of the Sauba ants, which have large external openings. The latter make houses by excavating, and sometimes undermine a hill so extensively, with their long galleries, that when a fire is lighted at one of the entrances to exterminate them, the smoke issues at numerous openings, distant perhaps a quarter of a mile from each other, showing in how many directions they have tunnelled out the hill, and that their winding passages communicate with each other throughout. So many travellers have given accounts of these ant-houses, and of the activity of their inhabitants in stripping and carrying off the leaves of trees to deposit them in their habitations, that it hardly seems worth while to repeat the story. Yet no one can see without astonishment one of these ant-armies travelling along the road they have worn so neatly for themselves, those who are coming from the trees looking like a green procession, almost hidden by the fragments of leaves they carry on their backs, while the returning troops, who have already deposited their burden, are hurrying back for more. There seems