1904. 



ANTHROPOID APES. 



433 



takes the latter. I am convinced that this is the right view to 

 take, and that many who side with Professor Matschie go too far 

 in splitting up the forms of Orang. Dr. Selenka gives a very 

 plausible and, I believe, well justified explanation for the exist- 

 ence of a number of local races in Borneo, viz., that the Orang- 

 Outans cannot swim and can only climb mountains, when bare of 

 trees, with diificulty ; and as Borneo is intersected in all directions 

 by broad rivers and high mountain-ranges, the Orangs in the 

 various districts are almost as much isolated as if confined to 

 separate islands. 



Text-fig. 114. 



Head of Simla pyjjmceus chimpaiise Matschie. (From life.) 



Dj-. Selenka separates 8 races of Orangs from Borneo and 

 Sumatra, 4 with cheek- callosities and 4 without, so that, as I 

 consider these two forms dimorphic phases, he distinguishes 

 actually 4 distinct subspecies. Professor Matschie distinguishes 

 14 races, or, as he calls them, species, from Borneo and Sumatra, 



Proc. Zool. See— 1904, Yol. II. No. XXVIII. 28 



