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into the Amazonian valley. Guiana still boasts such remarkable forms as the cardinal chatterer (Phamicocercus), the military chatterer (Hcematodervs), as well as Querula, Gymnoderus, and Gymnocephalus; but the first three pass to the south side of the Lower Amazon. Here also belong the cock of the rock (Rupicola), which ranges from Guiana to the Andes, and the marvellous umbrella-birds of the Rio Nigro and Upper Amazon (Cephalopterus), which extends across the Ecuadorean Andes and into Costa Rica. Brazil has PtilocMoris, Casiomis, Tijuca, Phibcdura, and Calyptura; while not a single genus of this family, except perhaps Reliochcera, is confined to the extensive range of the Andes. Almost the same phenomena are presented by the allied Pipridae or manakins, the greater part of the genera and species occurring in Eastern South America, that is in Brazil, Guiana, and the surrounding lowlands rather than in the Andean valleys. The same may be said of the jacamars (Galbulidae) and puff-birds (Bucconidae); but the humming-birds (Trochilidse) have their greatest development in the Andean district. Brazil and Guiana have each a peculiar genus of parrots; Guiana has three peculiar genera of Cracidae, while the Andes north of the equator have two. The Tinamidae on the other hand have their metropolis in Brazil, which has two or three peculiar genera, while two others seem confined to the Andes south of the equator. The elegant trumpeters (Psophiidae) are almost restricted to the Amazonian valley.
Somewhat similar facts occur among the Mammalia. At least 3 genera of monkeys are confined to the great lowland equatorial forests and 1 to Brazil; Icticyon (Canidae) and Pteronura (Mustelidae) belong to Guiana and Brazil; and most of the Echimyidae are found in the same districts. The sloths, anteaters, and armadillos all seem more characteristic of the eastern districts than of the Andean; while the opossums are perhaps equally plentiful in the Andes.
The preceding facts of distribution lead us to conclude that the highlands of Brazil and of Guiana represent very ancient lands, dating back to a period long anterior to the elevation of the Andean range (which is by no means of great geological antiquity) and perhaps even to the elevation of the continuous land which forms the hase of the mountains. It was, no doubt, during their slow elevation and the consequent loosening of the surface, that the vast masses of debris were carried down which filled up the sea separating the Andean chain from the great islands of Brazil and Guiana, and formed that enormous extent of fertile lowland forest, which has created a great continent; given space for the free interaction of the distinct faunas which here met together, and thus greatly assisted in the marvellous development of animal and vegetable life, which no other continent can match. But this development, and the fusion of the various faunas into one homogeneous assemblage must have been a work of time; and it is probable that most of the existing continent was dry land before the Andes had acquired their present altitude. The blending of the originally distinct sub-faunas has been no doubt assisted by elevations and depressions of the land or of the ocean, which have alternately diminished and increased the land-area. This would lead to a crowding together at one time, and a dispersion at others, which would evidently afford opportunity for many previously restricted forms to enter fresh areas and become adapted to new modes of life.
From the preceding sketch it will appear, that the great subregion of Tropical South America as here defined, is really formed of three originally distinct lands, fused together by the vast lowland Amazonian forests. In the class of birds sufficient materials exist for separating these districts; and that of the Andes contains a larger series of peculiar genera than either of the other sub-regions here adopted. But there are many objections to making such a sub-division here. It is absolutely impossible to define even approximate limits to these divisions—to say for example where the "Andes" ends and where "Brazil" or "Amazonia" or "Guiana" begins; and the unknown border lands separating these are so vast, that many groups, now apparently limited in their distribution, may prove to have a very much wider range. In mammalia, reptiles, and insects, it is even more difficult to maintain such divisions, so that on the whole it seems better to treat the entire area as one sub-region, although recognizing the fact of its zoological and geographical diversity, as well as its vast superiority over every other subregion in the number and variety of its animal forms.
The reptiles, fishes, mollusca, and insects of this sub-region have been sufficiently discussed in treating of the entire region, as by far the larger proportion of them, except in the case of land-shells, are found here.
Plate XV. Characteristic Neotropical Birds.—To illustrate the ornithology of South America we place our scene on one of the tributaries of the Upper Amazon, a district where this class of animals is the most prominent zoological feature, and where a number of the most remarkable and interesting birds are to be found. On the left we have the umbrella-bird (Cephalopterus ornatus), so called from its wonderful crest, which, when expanded, completely overshadows its head like an umbrella. It is also adorned with a long tassel of plumes hanging from its breast, which is formed by a slender fleshy tube clothed with broad feathers. The bird is as large as a crow, of a glossy blue-black colour, and belongs to the same family as the exquisitely tinted blue-and-purple chatterers. Flying towards us are a pair of curlcrested toucans (Pteroalossus beauharnaisii), distinguished among all other toucans by a crest composed of small black and shining barbless plumes, resembling curled whalebone. The general plumage is green above, yellow and red beneath, like many of its allies. To the right are two of the exquisite little whiskered hummers, or " frill-necked coquettes," as they are called by Mr. Gould, (Lophornis gouldi). These diminutive birds are adorned with green-tipped plumes springing from each side of the throat, as well as with beautiful crests, and are among the most elegant of the great American family of humming-birds, now numbering about 400 known species. Overhead are perched a pair of curassows (Crax globulosa), which represent in America the pheasants of the Old World. There are about a dozen species of these fine birds, most of which are adorned with handsome curled crests. That figured, is distinguished by the yellow caruncular swellings at the base of the bill. The tall crane-like bird near the water is one of the trumpeters, (Psophia leucoptera),eleg&at