line, the fall is about two hundred feet. The impression to the eye is, therefore, that of an absolute plain; and the flow of the water is so gentle that, in many parts of the river, it is hardly perceptible. Nevertheless, it has a steady movement eastward, descending the gentle slope of this wide plain, from the Andes to the sea; this movement, aided by the interflow from the south and north at opposite seasons, presses the bulk of the water to its northernmost reach during our winter months, and to its southernmost limit during our summer months. In consequence of this, the bottom of the valley is constantly shifting, and there is a tendency to form channels from the main river to its tributaries, such as we have seen to exist between the Solimoens and the Rio Negro,—such as Humboldt mentions between the Hyapura and the Amazons. Indeed, all these rivers are bound together by an extraordinary network of channels, forming a succession of natural highways which will always make artificial roads, to a great degree, unnecessary. Whenever the country is settled, it will be possible to pass from the Purus, for instance, to the Madeira, from the Madeira to the Tapajoz, from the Tapajoz to the Xingu, and thence to the Tocantins, without entering the course of the main river. The Indians call these passes ‘_furo_,’ literally, a bore,—a passage pierced from one river to another. Hereafter, when the interests of commerce claim this fertile, overflowed region, these channels will be of immense advantage for intercommunication.” CHAPTER XII. DESCENDING THE RIVER TO PARÁ.—EXCURSIONS ON THE COAST. FAREWELL VISIT TO THE GREAT CASCADE AT MANAOS.—CHANGE IN ITS ASPECT.—ARRIVAL AT VILLA BELLA.—RETURN TO THE HOUSE OF THE FISHERMAN MAIA.—EXCURSION TO THE LAGO MAXIMO.—QUANTITY OF GAME AND WATERFOWL.—VICTORIA REGIA.—LEAVE VILLA BELLA.—ARRIVE AT OBYDOS.—ITS SITUATION AND GEOLOGY.—SANTAREM.—VISIT TO THE CHURCH.—ANECDOTE OF MARTIUS.—A ROW OVERLAND.—MONTE ALÉGRE.—PICTURESQUE SCENERY.—“BANHEIRAS.”—EXCURSION INTO THE COUNTRY.—LEAVE MONTE ALÉGRE.—ANECDOTE OF INDIANS.—ALMEYRIM.—NEW GEOLOGICAL FACTS.—PORTO DO MOZ.—COLLECTIONS.—GURUPÁ.—TAJAPURÚ.—ARRIVE AT PARÁ.—RELIGIOUS PROCESSION.—EXCURSION TO MARAJO.—SOURÉS.—JESUIT MISSIONS.—GEOLOGY OF MARAJO.—BURIED FOREST.—VIGIA.—IGARAPÉ.—VEGETATION AND ANIMAL LIFE.—GEOLOGY.—RETURN TO PARÁ.—PHOTOGRAPHING PLANTS.—EXTRACT FROM MR. AGASSIZ’S NOTES ON THE VEGETATION OF THE AMAZONS.—PREVALENCE OF LEPROSY.