INTRODUCTION xix 



lo the mastication of any food, and are employed mainly for the storage 

 of such edibles as the animal does not desire to consume at the moment. 

 These receptacles even when full are no obstruction to the voice. 

 Besides these pouches large air sacs are present in the neck. The 

 species of the two genera Magus and Cynopithecus, although ranged 

 among the Baboons are generally known as Apes, probably on account 

 of the practical absence of a tail, resembling, as they do, in this respect, 

 the great Man-like Apes. The coat of the Baboon varies considerably 

 in texture from short silk-like hairs to almost a woolly fur observed in 

 those inhabiting a cold clime. The Mangabeys of the genus Cerco- 

 CEBUS, in some respects, are intermediate between the true Baboons 

 (Papio), and the Guenons (Pygathrix). They have no laryngeal 

 sacs, but possess the posterior fifth cusp in the last molar of each lower 

 jaw. Their form is more slender than that of the Baboons, resembling 

 the Guenons', and like them they have long tails, but the often brilliant 

 coloring of the Guenon is not seen in the coat of the Mangabey. The 

 genus Rhinostigma contains but one species remarkable for its 

 peculiar physiognomy ; the long white stripe from the forehead over 

 the nose to the upper lip, and the presence of a fifth posterior cusp 

 on each of the last lower molars, cause it to be a link between the Man- 

 gabeys and Guenons. The Guenons are the most numerous in species 

 of any of the groups belonging to the Lasiopygid^, are more slender in 

 form than the Mangabeys, have not the last cusp on the posterior lower 

 molar, and possess coats of many colors some with strongly contrasting 

 hues, and long tails. Miopithecus has two species the smallest of the 

 Guenons, and Erythrocebus follows with a dozen species, long- 

 legged and frequenters of the plains, rarely sojourning in forests. 

 The Langurs, Pygathrix, placed in a separate subfamily, are also of 

 a slender form v{ith the legs longer than the arms, very long tail, 

 cheek pouches absent, and a sacculated stomach of great complexity. 

 *Sir William Flower has described this organ as follows: "An ordinary 

 stomach must be supposed to be immensely elongated and gradually 

 tapering from the cardiac end to a very prolonged pyloric extremity. 

 Then two longitudinal muscular bands, corresponding in situation to 

 the greater and lesser curvature of an ordinary stomach — the former 

 commencing just below the fundus, and the latter at the cardiac orifice, 

 and both proceeding toward the pylorus — are developed so as to 

 pucker up the cavity into a number of pouches, exactly on the same 

 principle as the human colon is puckered up by its three longitudinal 



♦Animals Living and Extinct, p. 725. 



