224 THE GEOGRAPHY OF MAMMALS 



Gibbons vary much in the colour of their fur, and numerous 

 doubtful species have been based upon such differences. 

 The most recent authorities are not inclined to allow more 

 than seven or eight well-marked species of Gibbons. Of 

 them the most distinct is the Siamang (Hylobates syn- 

 dactylies) of the Malay Peninsula and Sumatra, which has 

 the second and third toes of the feet joined together by a 

 thin web of skin, and has other slight peculiarities, which 

 have induced some naturalists to place it in another genus. 

 But this seems to be quite unnecessary. The remaining 

 typical Gibbons are thinly distributed over all the three 

 great islands of the Malay Archipelago, Sumatra, Java, and 

 Borneo, extending into the Sulu group between Borneo and 

 the Philippines. On the continent they range high up the 

 Malay Peninsula, even so far north as Assam and Bhootan, 

 where they are represented by the Hoolock (H. hoolock). 

 They are also found in Siam, Cambodia, and Annam, and 

 one species (H. hainanus), has been discovered in the 

 Chinese island of Hainan. 



Thus of the three generally recognized genera of 

 SimiidcV, or Anthropoid Apes, one is of the Ethiopian, 

 the two others of the Oriental Region. 



We now come to the second family of Catarrhine 

 Monkeys, the Cercopithecidte, or what are usually called 

 the Old World Monkeys. Of these, about one hundred and 

 twenty species are known, divisible into about nine well- 

 marked genera. Most of these monkeys, as we shall show, 

 belong to the Oriental and Ethiopian Regions, but the genera 

 which inhabit these Regions respectively are quite distinct. 

 Two genera alone, Macacus and Semnopithecus, have repre- 

 sentatives within the limits of the Palsearctic Region. 



The Langurs (Semnopithecus) of the Oriental Region, 



