Not far above the _Infierno_ is the village of Mapire, a neat collection of perhaps fifty huts on a high bluff overlooking the river. In back of the town are vast _llanos_, or grassy plains, which are capable of supporting numerous herds of cattle. On the opposite side of the river, and some little distance up, is the mouth of the Caura, at one time believed to be the home of a tribe of headless people; but the old superstition has been overthrown, and during the first month of each year many adventurous parties ascend the river for a considerable distance in search of the _serrapia_ or tonca-bean. The tree (_Dipteryx odorata_) upon which the fruit grows resembles a mango, with spreading branches and deep-green, dense leaves. The fruit also is very similar to the mango, though green, with tough, fibrous flesh and a large seed. While the fruit is still green great quantities of it are destroyed by macaws and parrots, which take a bite or two, then drop the rest on the ground. Upon ripening, the fruit falls, when it is gathered into heaps and dried; the seeds are later cracked open and the strong-smelling kernel extracted to be carefully preserved and sent to Ciudad Bolivar, where it is treated in casks of rum and then exported. It is used in making perfumes and flavoring extracts. The water of the Caura is of a clear dark-red color, and for a great distance after entering the Orinoco the two waters flow side by side without mingling in the slightest degree. The Orinoco widens into a majestic stream above this point, and we estimated that the distance from bank to bank must in some places be from three to five miles; also, vast sand-banks stretch along both sides for a distance of many miles. Caicara, the only town of importance on the Orinoco besides Ciudad Bolivar, consisted at the time of our visit of about one hundred and fifty houses, but on account of a rubber and _serrapia_ boom on the Cuchivero many of the inhabitants were leaving for the latter place. The next day we passed the mouth of the Apure, and just beyond the mouth of the Arichuma; a great low, sandy island rises out of the centre of the Orinoco at this point, on which thousands of terns, skimmers, gulls, and other water-fowl were apparently nesting. All day long and even at night the air was filled with darting, screaming birds that made such a terrific din that it was impossible to sleep. High waves prevented our landing on the island, but the natives visit it regularly, taking away canoe-loads of eggs; for this reason the island has been named _Playa de Manteca_, meaning in this case land of plenty.