328 MR. R. LYDEKKER ON GUEREZA MONKEYS. [Nov. 28, 
and uniting on the lower part of the back. . The culmination of 
this type of coloration is formed by the White-tailed Guereza 
(C. caudatus, or albocaudatus as it ought to have been called) of 
the Kilimanjaro district and other parts of Eastern Africa. Here, 
as we see from text-fig. 57, the beautiful 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-fig. 58. 
White-thighed Guereza (Colobus vellerosus). 
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- 
conspicuous 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, 
