"Baboons often show their passion," as Mr. Darwin has related, "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 then alternately opening their mouths; and this action seems frequently to end in a real yawn. Mr. Bartlett believes that both animals wish 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.... 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 object in their beds of straw.... With several species of Baboons, the ridge of the forehead projects much over the eyes, and is studded with a few long hairs, representing our eyebrows. These animals are always looking about them, and in order to look upwards they raise their eyebrows. They have thus, as it would appear, acquired the habit of frequently moving the latter. However this may be, many kinds of Monkeys, especially the Baboons, when angered, or in any way excited, rapidly and incessantly move their eyebrows up and down, as well as the hairy skin of their foreheads." {258}Baboons are confined to the African continent and to Arabia, to the region, indeed, termed Ethiopian, as defined by Sclater and Wallace. They live chiefly on the ground, especially in rocky and barren hills, and less frequently among trees, for which their equally long front and hind limbs are not so well adapted. Mr. H. H. Johnson, C.B., now H.M. Commissioner in Nyasa-land, found, however, on his Kilimanjaro Expedition, that Baboons were singularly abundant in the big trees at Taveita, on the rise to that mountain. Their food consists of fruits and Lizards, but principally of insects, which they search for under stones, turning these over with their hands. They are, indeed, nearly omnivorous, as the reader will have gathered from Dr. Holub's observations. I. THE MANDRILL. PAPIO MAIMON. _Simia maimon_, Linn., Syst. Nat., p. 35 (1766). _Simia mormon_, Altstr., Acta. Noem., p. 144, pl. 3 (1766). _Papio maimon_, Erxl., Syst. Regne Anim., p. 17 (1777); Schl., Mus. Pays Bas, vii., p. 130 (1876). _Cynocephalus mormon_, Fr. Cuvier, Hist. Nat. Mammif., pp. 143, 146, pls. 52, 53 (1807). _Papio mormon_, Geoffr., Ann. Mus., xix., p. 104 (1812). _Mormon maimon_, Gray, Cat. Monkeys, Brit. Mus., p. 36 (1870).