_February 29th._—Early this morning we crossed the Pará River, and anchored at the entrance of the bay within which stands the town of Vigia. We landed, and while the boatmen were dragging the net, we wandered along the beach, which is bordered by thick forest, now full of flowers. Here we found the same geological formations as on the Marajo shore, and on the beach the counterpart of the ancient forest which Mr. Agassiz unearthed yesterday on the opposite coast. There can hardly be more convincing evidence that the rivers which empty into the Amazons near its mouth, like all those higher up, as well as the main stream itself, have cut their way through identical formations, which were once continuous. Evidently these remains of forests on the beaches of Vigia Bay and at the mouth of the Igarapé Grande are parts of one forest, formerly uninterrupted and covering the whole of the intervening space now filled by the so-called Pará River. We followed the beach to the entrance of an igarapé, which here opens into the river, and which looked most tempting with the morning shadows darkening its cool recesses. As the boatmen had not been very successful in fishing, I proposed we should put their services to better use and row up this inviting stream. To this day, though I have become accustomed to these forest water-paths and have had so many excursions in them, they have lost none of their charm. I never see one without longing to follow its picturesque windings into the depths of the wood; and to me the igarapé remains the most beautiful and the most characteristic feature of the Amazonian scenery. This one of Vigia was especially pretty. Clumps of the light, exquisitely graceful Assai palm shot up everywhere from the denser forest; here and there the drooping bamboo, never seen in the higher Amazons, dipped its feathery branches into the water, covered sometimes to their very tips with purple bloom of convolvulus; yellow Bignonias carried their golden clusters to the very summits of some of the more lofty trees; while white-flowering myrtles and orange-colored mallows bordered the stream. Life abounded in this quiet retreat. Birds and butterflies were numerous; and we saw an immense number of crabs of every variety of color and size upon the margin of the water. However, it was not so easy to catch them as it seemed. They would sit quietly on the trunks of all the old trees or decaying logs projecting from the bank, apparently waiting to be taken; but the moment we approached them, however cautiously, they vanished like lightning either under the water or into some crevice near by. Notwithstanding their nimbleness, however, Mr. Agassiz succeeded in making a considerable collection. We saw also an immense army of caterpillars, evidently following some concerted plan of action. They were descending the trunk of a large tree in a solid phalanx about two handbreadths in width, and six or eight feet in