When the sun has disappeared and made way for darkness, when the night breeze murmurs in the foliage, and the hollow sound of some unknown rivulet coursing over the gravel, is blended with the myriad indistinct noises of the insects hidden in the crevices of the trees and rocks; when the wild beasts, awaking at nightfall, leave their secret dens to proceed to their watering places, uttering at intervals hoarse yells--the forests in the pale moonbeams, which filter timidly through the branches, really become to the man who ventures into them the grand laboratory in which nature likes to assay in gloom and mystery the most powerful and strangest of her productions. There are accumulated, beneath the detritus piled up by centuries, the shapeless and yet imposing ruins of generations which have disappeared and left no sign; remnants of walls, pyramids, and obelisks rise at times before the startled eyes of the Indian or the hunter, as if to reveal to them that in times perhaps contemporary with the deluge, a powerful nation, now utterly effaced from the world, existed at this spot. Those who obstinately call America the New World, and deny the existence of the ruins with which this fertile soil is broadcast, have traversed this country like blind men, and have neither visited the splendid ruins of the Palenques, nor those which may be found at every step in the desert, by means of which some travellers have succeeded in settling the route followed by the migrations of the peoples that succeeded each other. The province of Coahuila in Mexico possesses several of these remains of great antiquity, which recall by their shape, and the way in which they are constructed, the _dolmens_ and _menhirs_ of old America. The travellers had established their camp in a vast clearing, in the centre of which was a gigantic monolith obelisk, so singularly placed on a block of stone that the slightest touch sufficed to give it a marked oscillating movement. This spot had a singular name, whose origin no one could have accounted for; the people of the country called it _Coatetl_, that is to say the home of the snake. This name, by the way, is found very frequently in Mexico, whose aborigines had a great respect for the snake, in consequence of their first legislator Quetzaltcoatl, that is to say, the "serpent covered with feathers."