504 QUADRUMANA. 



are often more artificial, or convenient, than strictly natural. On the one 

 hand, among the Cercopitheci are to be found species (the Malbrouck and 

 White-throated Monkey, for example) which, as far as form is concerned, 

 have as good a claim as the Macaque (Macacus cynomolgus), or the 

 Macacus carbonarius, to the genus Macacus, or, on the other hand, these 

 latter might, with equal propriety, be referred to the genus Cercopithecus. 

 On the contrary, the genus Macacus presents us with examples closely 

 approaching the Cynocephali, as the Macacus nemestrinus ; while, again, 

 the Gelada of Abyssinia, which appears referable to the genus Cynocepha- 

 lus, was placed by Riippell, its discoverer, in the genus Macacus. 



From the long-tailed, active, and lively Cercopitheci (or Guenons of 

 the French), to the short-tailed, heavy, ferocious Baboons, there is a 

 gradual and uninterrupted series of transitions, and it is rather by taking 

 locality into the account, and by tracing out a tendency to the same modi- 

 fications of form in other species, that the several genera can be settled. 

 The absence of a fifth tubercle, indeed, on the last molar tooth of the 

 lower jaw throughout the Cercopitheci, has been regarded as an index by 

 which to be guided, and as an important diagnostic mark of the genus. 

 It certainly cannot be overlooked ; and though it happens that in the three 

 species, viz., the Collared, the Sooty, and the Lunated White-eyelid 

 Monkeys (which may be justly separated from the genus Cercopithecus, 

 as the representatives of a sub-genus), the fifth tubercle on the molars in 

 question is present, the value of the character, as a diagnosis, is not 

 materially affected. With regard to the possession of laryngal sacculi, 

 which are considered, by most naturalists, to be wanting in the genus 

 Cercopithecus, it may be stated that, if not truly characteristic of the 

 animals of that group, they are not absolutely so either of the genera 

 Macacus,* or Cynocephalus ; but it is ascertained that some species, even 

 of Cercopithecus, possess them, as the Malbrouck and White-throated 

 Monkey ; while, on the other hand, the Author has failed to detect them 

 in specimens of the Toque (Macacus) radiatus, of the Pileated Monkey 

 (Macacus pileatus), of the Black Macaque (Macacus niger), and of the 

 Common Macaque (Macacus cynomolgus) ; and, farther, in an immature 

 female of the Cynocephalus Papio. Setting this point aside, a simple 

 stomach and large cheek-pouches are common to all. 



The tail, indeed, offers great variation in stoutness and length ; and 

 the muzzle is more developed in some species than in others ; and in 



* Cuvier says, speaking of the Macaques : "Us ont tous un sac qui communique avec le larynx 

 sous le cartilage thyro'ide, et qui se remplit d'air quand ils crient," which assertion is not confirmed, 

 in an absolute sense, by the author's investigations. It appears that these sacculi do not become de- 

 veloped until a certain age, and that in the females, of many species at least, they never acquire the 

 magnitude -which they assume in the males ; and hence it happens that, in the same species, they are 

 sometimes absent, sometimes present. 



