_January 26th._—Monte Alégre. Leaving Santarem on Tuesday we arrived here on Wednesday morning, and, as on our former visit, were received most hospitably at the house of Senhor Manuel. Mr. Agassiz and Mr. Coutinho have gone on a geologizing excursion to the Serra d’Ereré, that picturesque range of hills bounding the campos, or open sandy plain, to the northwest of the town. They took different routes, Major Coutinho, with Captain Faria and one or two other friends, crossing the campos on horseback, while Mr. Agassiz went by canoe. They will meet at the foot of the Serra, and pass two or three days in that neighborhood. Little is as yet known of the geological structure of the Amazonian Serras,—those of Santarem, of Monte Alégre, and of Almeyrim. Generally they have been considered as prolongations either of the table-land of Guiana on the north, or that of Brazil on the south. Mr. Agassiz believes them to be independent of both, and more directly connected with the formation of the Amazonian Valley itself. The solution of this question is his special object, while Major Coutinho has taken barometers to determine the height of the range. In the mean time, I am passing a few quiet days here, learning to be more familiar with the scenery of a region very justly called one of the most picturesque on the borders of the Amazons. Not only are the views extensive, but the friable nature of the soil, so easily decomposed, combined with the heavy rains, has led to the formation of a variety of picturesque dells and hollows, some of which have springs running into them, surrounded by rocky banks and overhung with trees. One of these is especially pretty; the excavation is large, and has the form of an amphitheatre; its rocky walls are crowned with large forest-trees, palms, mimosas, etc., making a deep shade; and at one side the spring flows down from the top of the cliff, with a pleasant ripple. Here the negro or Indian servants come to fill their water-jars. They often have with them the children under their charge; and you may sometimes see the large red jars standing under the mouth of the spring above, while white babies and dark nurses splash about in the cool water-basin below. Although in the campos the growth is low, and the soil but scantily covered with coarse grass and shrubs, yet, in some localities, and especially in the neighborhood of the town, the forest is beautiful. We have seen nowhere larger and more luxuriant mimosas, sometimes of a green so rich and deep, and a foliage so close that it is difficult to believe, at a distance, that its dense mass is formed by the light, pinnate leaves of a sensitive plant. The palms are also very lofty and numerous, including some kinds which we have not met before.