“As Rio de Janeiro is our starting-point, the water-system in its immediate neighborhood will be as it were a schoolroom for us during the first week of our Brazilian life. We shall not find it so easy a matter as it seems to keep our collections distinct in this region. The head-waters of some of the rivers near Rio, flowing in opposite directions, are in such close proximity that it will be difficult sometimes to distinguish them. Outside of the coast range, to which the Organ Mountains belong, are a number of short streams, little rills, so to speak, emptying directly into the ocean. It will be important to ascertain whether the same animals occur in all these short water-courses. I think this will be found to be the case, because it is so with corresponding small rivers on our northern coast. There are little rivers along the whole coast from Maine to New Jersey; all these disconnected rivers contain a similar fauna. There is another extensive range inland of the coast ridge, the Serra de Mantiquera, sloping gently down to the ocean south of the Rio Belmonte or Jequitinhonha. Rivers arising in this range are more complex; they have large tributaries. Their upper part is usually broken by waterfalls, their lower course being more level; probably in the lower courses of these rivers we shall find fishes similar to those of the short coast streams, while in the higher broken waters we shall find distinct faunæ.” The lecture closed with some account of the excursions likely to be undertaken in the neighborhood of Rio de Janeiro on arriving, and with some practical instructions about collecting, based upon Mr. Agassiz’s personal experience.[11] _April 14th._—Last evening was the most beautiful we have had since we left home; perfectly clear with the exception of soft white masses of cloud on the horizon, all their edges silvered by the moonlight. We looked our last for many months to come on the north star, and saw the southern cross for the first time. With the visible image I lost a far more wonderful constellation which had lived in my imagination; it has vanished with all its golden glory, a celestial vision as amazing as that which converted Constantine, and in its place stands the veritable constellation with its four little points of light.