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Show A~NOTATIONS AND ADDITIONS. 49 feet) lozccr. Farther to the west, near the junction of the Caura with the Orinoco, and to the cast of the mission of S. Pedro de Alcantara, an extensive tract of dense forest sank down in an earthquake in 1790, and a lake was formed of more than 300 toises (191 English feet) diameter. The tall trees (Desmanthus, Hymenreas, and l\falpighias) long retained their foliage and verdure under the water. ( 3) p. 26.-" We seem to see before us a shoreless ocean." The prospect of the distant Steifpe is still more striking, when the spectator has been long accustomed in the dense forests both to a very restricted field of view, and to the aspect of a rich and highly luxuriant vegetation. Ineffaceable is the impression which I received on our return from the Upper Orinoco, when, from the Hato del Capuchino, on a mountain opposite to the mouth of the Rio Apure, we first saw again the distant Steppe. The sun had just set; the Steppe appeared to rise like a hemi~::phere; and the light of the rising stars was refracted in the lowest stratum of air. The excessive heating of the plain by the vertical rays of the sun causes the variations of refraction-occasioned by the effects of radiation, of the ascending current, and of the contact of strata of air of unequal density- to continue through the entire night. (•) p. 26.-" The stony crust." Immense tracts of flat, bare rock form peculiar and characteristic features in the Deserts both of Africa and Asia. In the Schamo, which separates l\longolia and the mountain chains of Ulangom and 1\Ialak.ha-Oola from the north-west part of China, these banks of rock are called Tsy. They are also found in the forest-covered plains of the Orinoco, surrounded by the most luxuriant vegetation (Relation Hist. t. ii. p. 279). In the middle of these flat, tabular masses of granite and syenite of some thousand feet diameter, denuded of all vegetation save a few scantily distributed lichens, we find small islands of soil, covered with low and always flowering plants which give them the appearance of little gardens. The monks of the Upper Orinoco regard these bare and perfectly level surfaces of rock, when they are of considerable extent, as peculiarly 5 |