Few people in this country have any adequate conception of a tropical forest, and, consequently, are scarcely prepared to see whole races of animals constructed specially for a residence in the umbrageous wilderness within its pathless precincts. The great forest of the Amazon, in all its primeval grandeur, stretches for a thousand miles from north to south, and probably three or four hundred from east to west, and over all this vast extent of territory, so closely are the branches interwoven that, as we are told, a monkey might make his way passing from tree to tree without ever coming to the ground except at those points where the rivers hold their course through the tangled yet sublime scenery. "In these untrodden vastnesses the trees, rising frequently to a height of sixty or eighty feet, with stems perfectly straight and without a branch, give support to the huge creepers that climb around their trunks like immense serpents waiting for their prey, or sometimes stretching obliquely from their summits like the stays of a lofty mast, here twisting round each other till they form living cables, as if to bind securely the patriarchs of the forest; there wreathed in tangled festoons, and themselves covered with smaller creepers and parasitic plants." Such is Mr. Wallace's description of the interior of the Amazonian forest. [Illustration: Fig. 11.--VISCERA OF SMALL BIRD (_Euphone violaceus_). _a_, Crop; _b_, termination of the Windpipe, or inferior larynx; _c_, one of the Vocal Muscles; _d_, lower portion of the Gullet; _e_, the Gizzard; _g_, Lung of the right side; _h_, Liver; _i_, Alimentary Canal.] "The forests of Rio Janeiro," says Mr. Darwin, "are ornamented with the cabbage palm trees 110 feet high, with a stem so narrow that it might be clasped with two hands. The woody creepers themselves are of great thickness, some of them measuring two feet in circumference. If the eye was turned from the world of foliage above to the ground beneath, it was attracted by the extreme elegance of the leaves of the ferns and mimosæ (sensitive plants). The latter in some parts covered the ground; in walking across these thick beds, a broad track was marked by the change of colour produced by the drooping of their sensitive leaves. It is easy to specify the individual objects of admiration in these grand scenes, but it is not possible to give an adequate idea of the higher feelings of wonder, astonishment, and devotion, which fill and elevate the mind." These are the localities amongst which species of the ARBOREAL ORDERS find their Paradise, and hold undisturbed possession. Myriads of climbing birds--parrots, macaws, and cockatoos--fill the whole atmosphere with joyful screams, deafening the very monkeys with their din; gorgeous toucans, with enormous bills and feathers dipped in flame, and woodpeckers scarcely less gaily clad, make the woods echo, as with axe-like beaks they chop their way in search of insect food.