328 



MR, R. LYDEKKER ON GUEREZA MONKEYS. [Nov. 28, 



and uniting on the lower part of the back. The cnhnination of 

 this type of coloration is formed by the White-tailed Gnereza 

 (C. caudatus, or alhocaudatus as it ought to have been called) of 

 the Kilimanjaro district and other parts of Eastern Africa. Hei-e, 

 as we see from text-fig. 57, the beautifvil pendent white mantle 

 has become still longer, and the tail, which is wholly white except 

 for a very small length at the root, is clothed with long pendent hair 

 comparable to the " flag " of a setter ; the cheek- and throat- tufts, 

 however, have been completely lost, so that the head is wholly 

 short-haired, with the face and throat white. 



The difference between the species last-named and the Black 

 Guereza in the matter of colouring is enormous, and yet the 

 transition from the one to the other in this respect is almost 

 complete. In the case of the white-tailed species the excessive 



Text-fi2-. 58. 



White-tliighed Guereza (Colohus vellerosiis). 



length of the white hair forming the mantle and the tail-fringe 

 appears to have been evolved in order to render the creature as in- 

 conspicuovis as possible amid the long pendent greyish-white lichens 

 which clothe the branches of the trees of an East African forest. 

 The evolution of such a type is, of course, easy to comprehend ; 

 but, as in so many other cases, the difficulty comes in with regard 

 to the purpose of the coloration in the intermediate types con- 

 necting this species with the Black Guereza. What purpose do 

 these incipient attempts at the development of a pied coat serve ? 

 The line of evolution culminating in the white-tailed species by 

 no means, however, brings us to the end of the modifications in the 

 colour and local development of the hair in this group of monkeys. 



