PREHENSILITY OF TAIL 

 THE DIANA MONKEY 



The macaques of Asia are represented in Africa by 

 a kindred pair of genera of monkeys, known technically 

 and respectively as Cercopithecus and Cercocebus, and in 

 pseudo- vernacular, as Guenons and Mangabeys. They 

 have always long tails, which, as has been noted, the 

 macaques have not always ; and the mangabeys possess 

 no laryngeal pouch capable of inflation such as is to be 

 found in the macaques. The Cercopitheci are apt to 

 run to bright spots of colour about the nose, and their 

 fur generally is more gaily coloured than in the sombre 

 macaques. The Diana monkey, Cercopithecus diana, 

 is as good a type as any other of this extensive genus, 

 which contains more than forty species. This monkey 

 like some others of its congeners is bearded, white 

 bearded, and there is a good deal of bright chestnut or 

 orange colour about the body. It is like other guenons 

 essentially tree dwelling and social, moving about in 

 herds ; like most monkeys it is affable when young, 

 but morose and treacherous when older. Like all 

 others of the apes of the Old World its tail cannot grasp 

 the branches which it traverses in the fashion so con- 

 venient to most of the monkeys of America ; and that 

 there should be this distinction is one of the remark- 

 able facts about monkeys. Why a prehensile tail 

 should have been developed in one half of the globe 

 and not in the other in creatures which lead for all 

 practical purposes identical lives, and are plainly most 

 closely allied, is a mystery apparently insoluble. 

 Evolution seems so to speak to have gone out of its 

 way in denying this favour, which it has granted so 

 widely and to so many and such varied types of animals, 

 e.g. marsupials, lizards, snakes, etc., etc. Anyhow the 

 long tail of the Diana monkey and its immediate allies 

 is at best a balancing pole to secure a safe transit across 



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