Retrospective view of the districts which border steppes and deserts. Wilderness of the forest-region between the Orinoco and Amazon rivers. Native tribes separated by wonderful diversity both of language and customs; a toiling and divided race. Figures graven on rocks prove that even these solitudes were once the seat of a civilization now extinct—pp. 19–21. SCIENTIFIC ILLUSTRATIONS AND ADDITIONS pp. 22–152. The island-studded Lake of Tacarigua. Its relation to the mountain-chains. Geognostic tableau. Progress of civilization. Varieties of the sugar-cane. Cacao plantations. Great fertility of soil within the tropics accompanied by great atmospheric insalubrity.—pp. 22–26. Banks, or broken floetz-strata. General flatness. Land-slips—pp. 26–28. Resemblance of the distant steppe to the ocean. Naked stony crust, tabular masses of syenite; have they a detrimental effect on the atmosphere?—pp. 28–29. Modern views on the mountain systems of the two American peninsulas. Chains, which have a direction from S.W. to N.E., in Brazil and in the Atlantic portion of the United States of North America. Depression of the Province of Chiquitos; ridges as watermarks between the Guaporé and Aguapehi in 15° and 17° south lat., and between the fluvial districts of the Orinoco and Rio Negro in 2° and 3° north lat.—pp. 29–31. Continuation of the Andes-chain north of the isthmus of Panamá through the territory of the Aztecs, (where the Popocatepetl, recently ascended by Capt. Stone, rises to an altitude of 17,720 feet,) and through the Crane and Rocky Mountains. Valuable scientific investigations of Capt. Frémont. The greatest barometric levelling ever accomplished, representing a profile of the ground over 28° of longitude. Culminating point of the route from the coast of the Atlantic to the South Sea. The South Pass southward of the Wind-River Mountains. Swelling of the ground in the Great Basin. Long disputed existence of Lake Timpanogos. Coast-chain, Maritime Alps, Sierra Nevada of California. Volcanic eruptions. Cataracts of the Columbia River—pp. 31–38. General considerations on the contrast between the configuration of the territorial spaces, presented by the two diverging coast-chains, east and west of the central chain, called the Rocky Mountains. Hypsometric constitution of the Eastern Lowland, which is only from 400 to somewhat more than 600 feet above the level of the sea, and of the arid uninhabited plateau of the Great Basin, from 5000 to more than 6000 feet high. Sources of the Mississippi in Lake Istaca according to Nicollet, whose labours are most meritorious. Native land of the Bisons; their ancient domestication in Northern Mexico asserted by Gomara—pp. 38–42.