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Show 30 STEPPES AND DESERTS. latter far surpass the Llanos of V enezucla in area; and their extent is so great that, while their northern margin is bordered by palm trees, their southern extremity is almost continually covered with ice. The Tuyu, which resembles the Cassowary (the Struthio rhea), is peculiar to these Pampas, which are also the haunt of troops of dogs (15) descended from those introduced by the colonists, but which have become completely wild, dwelling together in subterranean hollows, and often attacking with blood-thirsty rage the human race whom their progenitors served and defended. Like the greater portion of the desert of Sahara, ('6) the northernmost of the South American plains, the Llanos, are in the torrid zone: during one-half of the year, they arc desolate, like the Lybian sandy waste; during the other, they appear as a grassy plain, resembling many of the Steppes of Central Asia. (17) It is a highly interesting though difficult task of general geography to compare the natural conditions of distant regions, and to represent by a few traits the results of this comparison. The causes which lessen both heat and drynes!! in the New World (18) are manifold, and in some respects as yet only partially understood. Amongst these may be classed the narrowness and deep indentation of the American land in the northern part of the torrid zone, where consequently the atmosphere, resting on a liquid base, does not present so heated an ascending current ;-the extension of the continent towards the poles ;-the expanse of ocean over which the trade-winds sweep freely, acquiring thereby a cooler temperature ;-the flatness of the eastern coasts ;-currents of cold sea-water from the antarctic regions, which, coming from the south-west to the north-east, first strike the coast of Chili in the parallel of 35° south latitude, and advance along the coast of Peru as far north as Cape Parifia, and then turn suddenly to the west;-the numerous lofty mountain chains rich in springs, and whose snow-clad summits, rising high above all the strata of clouds, cause descending currents of cold air to roll down their declivities ;-the abundance of rivers of enormous breadth, which, after many windings, seek the most distant coast;-Steppes which from not being sandy are less susceptible of acquiring a high degree of heat ;-impenetrable forests occupying the alluvia.} plains 13ituated immediately beneath the Equator, protectiv~ with t.\leir |