individual spider, but to belong to a whole family, or republic of spiders, which must be singularly social in their habits to form such an establishment. The New Shetland Isles, though separated from America, appear to form a continuation of the mountain system of that continent, their geological formation being generally precisely similar to that of Tierra del Fuego. They are mostly mountainous, and present an exceedingly dreary appearance, being in many parts covered with snow to the water's edge, and nearly destitute of vegetation. The New Orkneys, Enderby's Land, and Sandwich Land, all appear to present a similar forbidding aspect. Trinity, or Palmer's Land, and Graham's Land, are little known; the latter appears to be of considerable elevation, and is supposed to consist of continuous land. Biscoe's range, which is a group of islands lying to the west of Graham's Land, includes the beautiful and imposing Adelaide Island, which consists of an elevated snow-clad peak, shooting up into the clouds, and of a lower range of mountains, remarkable for having only a thin covering of snow on their summits, though towards their base, they are buried in a field of ice and snow of dazzling brightness. Near the water's edge, a ledge of rocks occurs, riven and splintered in every direction, as if by some violent convulsion. Owing to the great degree of cold, which, as has been before observed, prevails in the higher latitudes of the southern hemisphere, these islands are almost destitute of organized productions. The New Shetland Isles are situated in a lower parallel than Drontheim, in Norway, which, it will be remembered, is the northern limit of the cultivation of wheat; but, so severe is the climate of these southern lands, that the only vegetation consists of some straggling grass, and a species of lichen. No living quadrupeds have been found; and a very small number of birds; the latter consisting chiefly of penguins (fig, 138), and various species of petrel. CHAPTER XXI. GENERAL FEATURES OF CENTRAL AMERICA.-MEXICO. TEXAS.-GUATEMALA.-WEST INDIAN ISLANDS. There, groves that bloom in endless spring Are rustling to the radiant wing Of birds, in various plumage bright As rainbow-hues, or dawning light. And from the fruit-tree spreading tall Oft as sea-breezes blow.-WILSON. CENTRAL AMERICA, properly so called, consists of an extended strip of land, stretching from north-west to south-east, separating the waters of the Atlantic from those of the Pacific, and connecting the two vast peninsulas of North and South America. The natural limits of this territory are marked, on the one hand, by the narrowest part of the isthmus of Panama, and on the other, by the isthmus of Tehuantepec. As, however, the physical features of the extensive territory of Mexico agree in many particulars with those of this portion of the New World, that region may be advantageously considered in the same division; in which we shall also place the large and important assemblage of islands, included under the general name of the West Indies. The grand central mountain range, which in North America bears the name of the Rocky Mountains, and in South America, that of the Andes, may be traced through the whole of Mexico and Central America, but does not, in any part of these regions, attain the lofty elevation to which it rises in those vast and extensive mountain systems. In Mexico, the central line is continued in an elevated plateau, which constitutes the highest portion of the ridge, being on an average about seven thousand feet above the level of the sea, and extending from one extremity of Mexico to the other. This plateau is traversed, nearly at right angles, by a chain of active volcanos, some of which are of great elevation, and which extend from east to west. Mexico is rich in mineral deposits; iron, copper, lead, and mercury occur in some parts; and gold is also met with; but the most celebrated deposits are the silver mines, which are about three thousand in number. The mean annual produce of the latter mines is estimated at 1,500,000 lbs. ; a quantity considered equal to two-thirds of the silver annually obtained from the earth over the whole surface of the globe. Mexico, owing to its geographical position, and also to the peculiar configuration of its surface, presents some remarkable features in its natural productions. The most elevated part of its high table land is absolutely devoid of vegetation. This is not, however, attributable to its altitude, and consequent low temperature; its elevation not being sufficient to produce this effect in the parallel in which it is situated; but is apparently caused by its want of moisture, which in great measure arises from the porous nature of the rocks. The surface is also covered with a saline efflorescence, which increases its unfitness for vegetation. As soon, however, as any slopes occur, a more humid climate prevails, and these districts are adorned with vegetation of extreme variety and beauty. The central portion of the plateau is traversed by numerous valleys, the wide basins of which are usually not more than one thousand feet above the level of the sea. In the more elevated parts of these valleys, the steep declivities are occupied by forests of pine, oak, and beech, whilst the basins are adorned with the graceful foliage of the palm, and other tropical plants. And thus, the traveller, passing down one of these magnificent ravines, finds himself almost suddenly transported from the midst of the productions of temperate climes, to those of the torrid zone. Among the vegetable productions of Mexico we meet with many North American species; but its fiora has, on the whole, a greater similarity to that of South America. Thus, in the valleys, we meet with the caoutchouc tree, the cow-tree, the banana, vanilla, agave, or American aloe (fig. 168), &c. The most characteristic feature, however, of the Mexican flora, is the vast abundance of plants of the cactus kind, the latter CHAPTER XXI. GENERAL FEATURES OF CENTRAL AMERICA.-MEXICO.TEXAS.-GUATEMALA.-WEST INDIAN ISLANDS. There, groves that bloom in endless spring Are rustling to the radiant wing Of birds, in various plumage bright As rainbow-hues, or dawning light. And from the fruit-tree spreading tall Oft as sea-breezes blow.-WILSON. CENTRAL AMERICA, properly so called, consists of an extended strip of land, stretching from north-west to south-east, separating the waters of the Atlantic from those of the Pacific, and connecting the two vast peninsulas of North and South America. The natural limits of this territory are marked, on the one hand, by the narrowest part of the isthmus of Panama, and on the other, by the isthmus of Tehuantepec. As, however, the physical features of the extensive territory of Mexico agree in many particulars with those of this portion of the New World, that region may be advantageously considered in the same division; in which we shall also place the large and important assemblage of islands, included under the general name of the West Indies. The grand central mountain range, which in North America bears the name of the Rocky Mountains, and in South America, that of the Andes, may be traced through the whole of Mexico and Central America, but does not, in any part of these regions, attain the lofty elevation to which it rises in those vast and extensive mountain systems. In Mexico, the central line is continued in an elevated plateau, which constitutes the highest portion of the ridge, being on an average about seven thousand feet above the level of the sea, and extending from one extremity of Mexico to the other. This plateau is traversed, nearly at right angles, by a chain of active volcanos, some of which are of great elevation, and which extend from east to west. Mexico is rich in mineral deposits; iron, copper, lead, and mercury occur in some parts; and gold is also met with; but the most celebrated deposits are the silver mines, which are about three thousand in number. The mean annual produce of the latter mines is estimated at 1,500,000 lbs. ; a quantity considered equal to two-thirds of the silver annually obtained from the earth over the whole surface of the globe. Mexico, owing to its geographical position, and also to the peculiar configuration of its surface, presents some remarkable features in its natural productions. The most elevated part of its high table land is absolutely devoid of vegetation. This is not, however, attributable to its altitude, and consequent low temperature; its elevation not being sufficient to produce this effect in the parallel in which it is situated; but is apparently caused by its want of moisture, which in great measure arises from the porous nature of the rocks. The surface is also covered with a saline efflorescence, which increases its unfitness for vegetation. As soon, however, as any slopes occur, a more humid climate prevails, and these districts are adorned with vegetation of extreme variety and beauty. The central portion of the plateau is traversed by numerous valleys, the wide basins of which are usually not more than one thousand feet above the level of the sea. In the more elevated parts of these valleys, the steep declivities are occupied by forests of pine, oak, and beech, whilst the basins are adorned with the graceful foliage of the palm, and other tropical plants. And thus, the traveller, passing down one of these magnificent ravines, finds himself almost suddenly transported from the midst of the productions of temperate climes, to those of the torrid zone. Among the vegetable productions of Mexico we meet with many North American species; but its flora has, on the whole, a greater similarity to that of South America. Thus, in the valleys, we meet with the caoutchouc tree, the cow-tree, the banana, vanilla, agave, or American aloe (fig. 168), &c. The most characteristic feature, however, of the Mexican flora, is the vast abundance of plants of the cactus kind, the latter |