The Caiarára keeps the house in a perpetual uproar where it is kept. When alarmed or hungry, or excited by envy, it screams piteously, and it is always making some noise or other, often screwing up its mouth, and uttering a succession of loud notes resembling a whistle. Mr. Bates’s little pet used to run after him, supporting himself for some distance on his hind legs, without, however, having been taught to do so. The end of this friendship came at last, and in a tragical manner. “He offended me greatly one day by killing, in one of his jealous fits, another and much choicer pet--the Nocturnal Owl-like Monkey (_Nyctipithecus trivirgatus_). Some one had given this a fruit which the other coveted, so the two got to quarreling. The Nyctipithecus fought only with its paws, clawing out, and hissing like a Cat. The other soon obtained the mastery, and before I could interfere, finished its rival by cracking its skull with his teeth. I then got rid of him.” [Illustration: BROWN CAPUCHIN. (_From the Zoological Gardens._)] Broderip writes about one as follows:--“Humboldt saw at Maypures one of these Monkeys riding a Pig. He used to bide his time, and every morning caught one, which he compelled to perform the part of the horse. Seated on pig-back did he majestically ride about the whole day, clinging to his bristly steed as firmly as ever the Old Man of the Sea clung to Sindbad, not even giving poor piggy a respite at meal times, but continually bestriding him all the time he was feeding in the savannah that surrounded the Indian huts. A missionary had another of these riders, but the missionary’s Monkey laid a strong hold on a comfortable Cat which had been brought up with him, carried him well, and bore all his tricks with patience and good humour.” The skull is long, and uniformly round in these animals, and the face is not very prominent. There are two nasal bones, and the inter-maxillary bone is distinct; moreover, the chin is rounded and receding. With all its powers of teasing, fun, and its intelligence, one would anticipate that the brain would be far superior in its form to the Spider and other Monkeys with prehensile tails; and this is the case, for the convolutions on the outside are almost equal in their number and relative size to those of the Monkeys of the Old World. There are eighteen kinds of these Capuchins, and the attempt has been made to classify them by the direction of the hair of the head and its colour, but in doing this sufficient allowance has not been made for the influence of sex, age, and the bodily vigour, so that great confusion still exists in their classification. THE BROWN CAPUCHIN.[90] In this species the hairs of the head are brushed back, but it appears that with age some hairs are erected at the sides of the head above the ears into two horns, so as to give it the name of the Horned Monkey. THE WEEPER CAPUCHIN, OR CAI.[91]