32 MAMMALS OF THE 



from the other Hylobates-s^ecies that it never has been 

 confounded with them. The remaining ones however always 

 are very puzzling, so that while some naturalists have 

 distinguished seven species , others are inclined to accept 

 merely five or a still smaller number of species. Dr. J. E. 

 Gray (Catalogue of Monkeys , Lemurs and fruit-eating Bats , 

 1870) said: »the species {oi Hylobates) are very much alike 

 in appearance , and are variable in colour from the same 

 locality, so that one almost doubts their distinctness." Dr. 

 Ö. Muller concluded in 1844 (Ueber die auf den Sunda- 

 Inseln lebenden ungeschwanzten Affen-arten) : »mehr als 

 diese vier Arten von Hylobates {syndactylus from Sumatra , 

 leuciscus from Java , concolor from Borneo and variegatus 

 from Sumatra) kommen auf den Ostindischen Insein nicht 

 vor, welche Mühe auch manche gelehrte Naturforscher sich 

 geben mogen , um deren Anzahl , durch kleinliche Unter- 

 scheidungen und durch Aufstelluug von unhaltbaren Kenn- 

 zeichen, zu vergrösseren." S. Muller was convinced that 

 H. Rajiesii, variegatus and agilis are varieties of one and 

 the same species. Mr. Hose (A descriptive account of the 

 Mammals of Borneo, 1893) came to the conclusion that 

 Hylobates Miilleri and H. leuciscus cannot be separated. 



A careful study of the whole group probably will bring 

 forth that Dr. Gray was the nearest to the truth. 



As to the Bornean Hylobates collected by Büttikofer it 

 is a very striking fact that all the specimens collected on 

 Mount Liang Koeboeng belong to the dark species described 

 as H, Miilleri^ while all those from Roema Manoeal 

 are light colored individuals of the H. concolor-yaneij. 

 The specimens in our Museum collected in south-eastern 

 Borneo (Sakoembang and Pamattan) are dark colored like 

 Büttikofer's specimens from Mount Liang Koeboeng; our 

 specimens from Western Borneo (Pontianak) have a light 

 hue like those from Mount Kenepai , so that it might appear 

 as if the Kapoeas-river is a natural barrier between the 

 two differently colored groups. Mr. Hose however obtained 

 eleven specimens , five of which were in the same troop 



r*iotes from the I^eyden ^useuia, ~Vol. ILIX.. 



