These curious little creatures are noted for forming a friendship with other animals when in captivity. Baron Humboldt mentions one which used to mount on the back of a pig every morning, and continued sitting there during the whole of the day; and even when the pig went out feeding on the campos, it still kept its seat, riding back again in the evening to its home. Others have been known to choose cats for their steeds, and perseveringly to keep their hold in spite of their active movements-- seeming to enjoy them as much as the llanero does those of a colt he is engaged in breaking-in. PARAUACU. On the dry lands to the north of the Upper Amazon, a little timid inoffensive monkey is found with a long bear-like coat of speckled grey hair. The long fur hangs over its head, half concealing a pleasing diminutive face; the tail--to the very tip--which is of some length, is also completely covered. PITHECIA HIRSUTA--PITHECIA ALBICANS. There are two more species--the Pithecia hirsute and the Pithecia albicans. They are especially capable of attachment to those who treat them kindly. Being somewhat dull and cheerless, they seldom indulge in the usual sportive movements of their race. Mr Bates relates that a friend of his possessed one of these little creatures. His friend, accompanied by the monkey, was in the habit of paying him a daily visit. One day the little animal, having missed its master, concluded, as it seemed, that he had gone to his house, and accordingly came straight to it, taking a short cut over gardens, trees, and thickets. This it had never done before; they learned it, however, from a neighbour who had observed its movements. On arriving at Mr Bates's house and not observing its master, it climbed to the top of the table, and sat with an air of quiet resignation waiting for him. Shortly afterwards he arrived, and the gladdened pet then jumped to its usual perch on his shoulder. SAIMIBI--CALLITHRIX--TEETEE--COLLARED TEETEE. There is another genus of light and graceful little monkeys, known by the name of Callithrix, or "beautiful hair." Among them is the Saimiri, or teetee, of which there are several species. The collared teetee is among the most attractive--Callithrix torquatus. The general colour is a greyish-olive, the limbs looking as if washed with a rich golden hue. The ears are white, and the body whitish-grey. The tip of the long tail is black.