﻿E. LÖNNBERG, NEW GUEREZA. 11 



wishes to make sure about this it may be recommended to look 

 for instance at the plates in Pocock's valuable »Monografic 

 Revision of the Monkeys of the Genus Cercopithecus».^ Bright 

 coloured whiskers and brow-bands are there shown to be of 

 common occurrence. Similar characteristics are also found 

 among other genera for instance Semnopithecus etc. Bright 

 coloured hair are often found in the perineal region of mon- 

 keys and the tail or the tip of the same has often a differ- 

 ent shade than the general colour of the back. If such an 

 explanation of the »incipient attempts at the development 

 of a pied coat» {15) is accepted as I think it may, the fur- 

 ther development of the white hair, when it proves useful 

 in making the animals less conspicuous among the v/hitish 

 lichens and other epiphytes, is easy to comprehend. The 

 shoulder-tufts are in the first stages only a backward pro- 

 longation of the white whiskers. 



Such a view as the one set forth above appears to be 

 strengthened by the fact that even such black and white 

 Guerezas in which the white mantle is missing, are provided 

 with the white marks in the face — whiskers and brow- 

 band — and in the perineal region or on the tighs and on 

 the tail, consequently in such places where monkeys are apt 

 to have ornamental (or recognition) marks of obvious coloura- 

 tion. It is thus evidently of primary inportance for the 

 Guerezas to have white marks at these places! Then there 

 is another question, whether the present colouration of 

 such Guerezas as for instance Colubus vellerosus is to be 

 regarded as the result of a »retrograde development» (15) 

 that is, whether a reduction of a formerly existing white 

 mantle has taken place, or if these forms simply have not 

 needed the development of such a mantle because the sur- 

 roundings did not require it. It is difficult to say which of 

 these theories is the correct one, perhaps both are applicable 

 although in different species. The former appears to be sup- 

 ported by the fact that the young of Colohus ursinus is said 

 to be wholly »white with a few scattered black hairs; tail 

 well tufted».^ The young is thus in this case more white 



1 Proc. Zool. Soc. London 1907, p. 677- 



^ Jentink, Notes Leyden Museum Vol X, 1S88 and Forbes, H. O. : 

 A Handbook to the Primates. Vol. II p. 94. Allen's Nat. Hist. Libr. 

 London 1894. 



