Memoir on a new Species of Monkey found in the eastern Declivity of the Andes. By M. de Humboldt . From Recueil d'Observations de Zoologie et d' Anatomie compare, 1re livraison. In the vast plains which extend from the eastern declivity of the Andes towards the shores of the Brazils, in the thick forests on the Amazons, Rio Negro (Black River), and Oronoco, the cavia capybara, sus tajassu, and the monkeys, are the quadrupeds most common. The marmose and alouate prevail over all the others, whether for variety of species or number of individuals. Some of these monkeys, such as the capuchin of Oronoco, very different from the simia capucina Linn., the tiger-monkey or cusicusi, and the widow, (three new species which I have discovered,) live in pairs, melancholy, mistrustful, flying (like man in a savage state) their proper species. Others, especially the sagouin and howling monkey, are seen in troops, from 80 to 100, springing from branch to branch in search of nourishment. The saimiri of Buffon, that are the titi of Atures (simia sciurea), so esteemed on account of their gaiety, their mildness, and extreme littleness, assemble together when it begins to rain. A fall of temperature of three or four degrees of the centigrade thermometer disturbs them so much, that they mutually embrace each other and form balls or knots, of which each individual seeks to occupy the middle, in order to find shelter. The Indian hunters, advertised by the cry of the titi, direct their arrows towards these flocks. Notwithstanding the great number of monkeys that naturalists have described, it is probable that we are still ignorant of the tenth part existing. In Africa, and even in South America, there are vast plains of twenty thousand square leagues which have not yet been visited by any European. On the other hand, the monkeys the most common are still so imperfectly represented even in the most recent works, executed with the greatest elegance, that those who have seen the living individuals would have difficulty to recognise them in the drawings published. Of this I might cite as examples the simia sciurea, varieties of the simia capucina, and even the simia paniscus, which is the game commonly eaten in the Upper Oronoco. Among the great number of new sapajous, or marmoses, that I had the opportunity of describing in my voyage to the tropics, I have chosen a monkey of the plains of Mocoa, remarkable for its resemblance with the lion of Africa, of which I made a drawing during my residence at Popayan. My sketch has been copied and improved by M. Turpin. (Plate VIII.) The leoncito is very rare, even in its native country. It inhabits the plains which border on the eastern declivity of the Cordelliers, the fertile banks of the Putumayo and Caqueta: it never ascends even to the temperate regions, while the wandering bands of the simia beelzebul sometimes push their excursions to heights equal to those of Canigou, and even Mont Perdu. The leoncito of Mocoa, which I name simia leonina, differs essentially from all known species. It has not the white head of the s. leucocephala figured in the work of Audebert. It differs from the s. rosalia, and the saki or fox-tailed monkey (s. pithecia), by a white spot which covers the top of the nose, the mouth, and the chin; and from the s. iacchus of Brazil, by a tail without white rings, by its black visage, and by the disparity of conformation that exists between the claws of its fore-feet and the nails on its hinder ones; the former almost resembling the claws of a cat, and the latter having nails like the human toes. The leoncito is but seven or eight inches long, without counting the tail, which is of the length of the body. It is one of the least and most elegant monkeys that we have seen. It is gay and sportive, but, like most little animals, very irascible. When it is vexed it bristles up the hair on its neck, that increases its resemblance to the African lion. I have seen but two individuals of this very rare monkey: they were the first that had been brought living to the west of the Cordellier. They were kept in a cage; and their movements were so rapid and so continual, that I had much difficulty to design them. Their hissing imitates the song of little birds, and I suppose that the conformation of their larynx (having a particular sac) is analogous to that which I have described in the simia oedipus. I have been assured, that in the cottages of the Indians of Mocoa the leoncito breeds in the domestic state. By the way of Grand-Para and the river of Amazons they might be brought into Europe. If a government, interested in the progress of descriptive natural history, would undertake an expedition in which that interest would not be rendered subservient to geographical discoveries; if that government sent canoes or small boats to ascend the Oronoco, and to penetrate by the Casiquiare and Rio Negro to the river of Amazons; in short, if, after having explored the mouths of the Caqueta and Putumayo, it would make these same boats descend to Grand-Para, it would in a little time unite collections the most precious to the study of zoology and botany. Such an expedition would be of little expense, and its success certain. Leoncito, from leon (lion) a diminutive of endearment more common even with the Spaniards than the Italians.--Translator. SIMIA leonina. Ex olivaceo fuscescens, facie atra, ore albo, dorso striis albo-flavescentibus notato. Caput parvum, depressum, nigrescens. Facies anthropomorpha, atra; macula albo-caerulescens circa os et nares. Auriculae subtriangulares distantes, margine superiori deflexo, magnae, aterrimae, pilosae. Corpus ex badio olivaceum, pilis nigro-annulatis, in collo longioribus. Dorsum maculis et striis albo-flavescentibus variegatum. Cauda non prehensilis, longitudine corporis, superne atra, inferne badia, apice incurva et incrassata. Manus et pedes aterrimi, inferne nudi, pollice in manibus anterioribus et posteriorbus distante. Ungues acuti, incurvi, atri; pollicis ungue in manibus anterioribus oblongo, acuto, in manibus posterioribus (pedibus) obtuso, anthropomorpho. Abbildungen