“This emotion is often exhibited by many kinds of Monkeys, and is expressed, as Mr. Martin remarks, in many different ways. Some species, when irritated, pout the lips, gaze with a fixed and savage glare on their foe, and make repeated short starts as if about to spring forward, uttering at the same time inward guttural sounds. Many display their anger by suddenly advancing, making abrupt starts, at the same time opening the mouth, and pursing up the lips so as to conceal the teeth, while the eyes are daringly fixed on the enemy as if in savage defiance. Some again, and principally the long-tailed Monkeys, or Guenons, display their teeth, and accompany their malicious grins with a sharp, abrupt, reiterated cry. Mr. Sutton confirms the statement that some species uncover their teeth when enraged, whilst others conceal them by the protrusion of their lips, and some kinds draw back their ears. The _Cynocephalus niger_, lately referred to, acts in this manner, at the same time depressing the crest of hair on its forehead, and showing its teeth, so that the movements of the features from anger are nearly the same as those from pleasure; and the two expressions can be distinguished only by those familiar with the animal. “Baboons often show their passion, and threaten their enemies in a very odd manner, namely, by opening their mouths widely, as in the act of yawning. Mr. Bartlett has often seen two Baboons, when first placed in the same compartment, sitting opposite to each other, and thus alternately opening their mouths; and this action seems frequently to end in a real yawn. Mr. Bartlett believes that both animals wished to show to each other that they are provided with a formidable set of teeth, as is undoubtedly the case. As I could hardly credit the reality of this yawning gesture, Mr. Bartlett insulted an old Baboon, and put him into a violent passion, and he almost immediately thus acted. Some species of Macacus and of Cercopithecus behave in the same manner. Baboons likewise show their anger--as was observed by Brehm with those which he kept alive in Abyssinia--in another manner, namely, by striking the ground with one hand, like an angry man striking the table with his fist. I have seen this movement with the Baboons in the Zoological Gardens, but sometimes the action seems rather to represent the searching for a stone or other objects in their beds of straw. Mr. Sutton has often observed the face of the Rhesus Monkey, when much enraged, growing red. As he was mentioning this to me another Monkey attacked a Rhesus, and I saw its face redden as plainly as that of a man in a violent passion. In the course of a few minutes after the battle the face of this Monkey recovered its natural tint; at the same time that the face reddened, the naked posterior part of the body, which is always red, seemed to grow still redder, but I cannot positively assert that this was the case. When the Mandrill is any way