CHAP. XIV.] 
THE NEOTROPICAL REGION. 
25 
is in peculiar types of all the most characteristic American 
families, such as the Tanagridse, Tyrannidm, Cotingidse, Formi- 
cariidse, Trochilidse, and G-albulidse. 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 land- 
birds 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 satis- 
factory result. 1 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 (Mniotiltidse) 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 (Tanagridse) are found here only, with an immense 
number of Fringillidse, — the former confined to the forests, the 
latter ranging to the upland plains. The ant-thrushes (Formi- 
cariidse) on the other hand seem more abundant in the lowlands, 
many genera being peculiar to the Amazonian forests. The su- 
perb chatterers (Cotingidse) 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.) 
