_August 20th._—On board the “Icamiaba.” Our first Sunday on the Amazons; for, notwithstanding the warm dispute as to whether both the rivers enclosing the island of Marajó must be considered as parts of the great river, it is impossible not to feel from the moment you leave Pará that you have entered upon the Amazons. Geology must settle this knotty question. If it should be seen that the continent once presented an unbroken line, as Mr. Agassiz believes, from Cape St. Roque to Cayenne, the sea having encroached upon it so as to give it its present limits, the Amazons must originally have entered the ocean far to the east of its present mouth, at a time when the Island of Marajó divided the river in two channels flowing on either side of it and uniting again beyond it. We came on board last night, accompanied to the boat by a number of the friends who have made our sojourn in Pará so agreeable, and who came off to bid us farewell. Thus far the hardships of this South American journey seem to retreat at our approach. It is impossible to travel with greater comfort than surrounds us here. My own suite of rooms consists of a good-sized state-room, with dressing-room and bath-room adjoining, and, if the others are not quite so luxuriously accommodated, they have space enough. The state-rooms are hardly used at night, for a hammock on deck is far more comfortable in this climate. Our deck, roofed in for its whole length, and with an awning to let down on the sides, if needed, looks like a comfortable, unceremonious sitting-room. A table down the middle serving as a dinner-table, but which is at this moment strewn with maps, journals, books, and papers of all sorts, two or three lounging-chairs, a number of camp-stools, and half a dozen hammocks, in one or two of which some of the party are taking their ease, furnish our drawing-room, and supply all that is needed for work and rest. At one end is also a drawing-table for Mr. Burkhardt, beside a number of kegs and glass jars for specimens. This first day, however, it is almost impossible to do more than look and wonder. Mr. Agassiz says: “This river is not like a river; the general current in such a sea of fresh water is hardly perceptible to the sight, and seems more like the flow of an ocean than like that of an inland stream.” It is true we are constantly between shores, but they are shores, not of the river itself, but of the countless islands scattered throughout its enormous breadth. As we coast along their banks, it is delightful to watch the exquisite vegetation with which we have yet to become familiar. The tree which most immediately strikes the eye, and stands out from the mass of green with wonderful grace and majesty, is the lofty, slender Assai palm, with its crown of light plume-like leaves, and its bunches of berry-like fruit, hanging from a branch that shoots out almost horizontally, just below the leaves. Houses on the shore break the solitude here and there.