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is in peculiar types of all the most characteristic American families, such as the Tanagridæ, Tyrannidæ, Cotingidæ, Formicariidæ, Trochilidæ, and Galbulidæ. A considerable proportion of the genera of the Chilian and Mexican sub-regions also occur here, so that out of about 680 genera of Neotropical landbirds more than 500 are represented in this sub-region.
Without entering minutely into the distribution of species it is difficult to sub-divide this extensive territory with any satisfactory result. The upland tract between the Amazon and Orinooko, which may be termed Guiana, was evidently once an island, yet it possesses few marked distinctive features. Brazil, which must have formed another great island, has more speciality, but the intermediate Amazonian forests form a perfect transition between them. The northern portion of the continent west of the Orinooko has more character; and there are indications that this has received many forms from Central and North America, and thus blended two faunas once more distinct than they are now. The family of wood-warblers (Mniotiltidæ) seems to have belonged to this more northern fauna; for out of 18 genera only 5 extend south of the equator, while 6 range from Mexico or the Antilles into Columbia, some of these being only winter immigrants and no genus being exclusively South American. The eastern slopes of the Andes constitute, however, the richest and best marked province of this sub-region. At least 12 genera of tanagers (Tanagridæ) are found here only, with an immense number of Fringillidæ,—the former confined to the forests, the latter ranging to the upland plains. The ant-thrushes (Formicariidae) on the other hand seem more abundant in the lowlands, many genera being peculiar to the Amazonian forests. The superb chatterers (Cotingidæ) also seem to have their head-quarters in the forests of Brazil and Guiana, and to have thence spread
1 Messrs. Sclater and Salvin, and Professor Newton, divide the Neotropical Region into six sub-regions, of which our “ Brazilian sub-region” comprises three-the “ Brazilian," the “ Amazonian," and the “ Columbian ;” but, after due consideration, it does not seem advisable to adopt this subdivision in a general work which treats of all the classes of terrestrial animals. (See p. 27.)