DISTRIBUTION OF MAMMALS 171 



and Chinese Subregions, but it lacks some of the northern ele- 

 ments present in each. On the Malay Peninsula there are like- 

 wise several forms that do not occur on any of the nearby 

 islands ; those elements are chiefly Indian or Chinese forms, 

 such as the gaur, a large species of bamboo rat, several squirrels, 

 the large Indian and Burma civets, and the stump-tailed ma- 

 caque monkey. 



Sumatra is populated by mammals closely related to those of 

 the Malay Peninsula ; a few Malay forms absent from the other 

 islands are tapir, serow, brush-tailed porcupine, and the siamang 

 gibbon. Faunal relationships between Sumatra and Borneo are 

 close; the tana tree shrew, the tarsier, the orang, the thick- 

 spined porcupine, and the whitish species of the Oriental squir- 

 rel are elements present on both islands but absent from the 

 Malay Peninsula and Java. On the other hand, several mam- 

 mals are common only to Java and Sumatra: the Java tree 

 shrew, the mink-like Java weasel, and one of the shrew rats. A 

 native rabbit or hare, short-eared and striped with black, is 

 thought to be allied to the coarse-haired rabbits of the Himala- 

 yan foothills and southern China. 



The Mentawi Islands, off western Sumatra, have some well- 

 marked local forms such as the dwarf gibbon, a distinctive leaf 

 monkey and the peculiar pig-tailed langur. The relationships 

 of the other mammals are Sumatran. 



Borneo, the largest of the islands, has more varied climatic 

 and environmental conditions than other Greater Sunda Islands, 

 or even than the Malay Peninsula. The mountains of the in- 

 terior are a barrier dividing the lowlands of the northwestern 

 part of the island from those of the southeastern. They provide 

 conditions suitable for mountain-living species. Some of the 

 large rivers also form barriers and restrict the ranges of cer- 

 tain species and races. A few high peaks, such as Kina Balu in 

 the north and isolated Poi and Penrissen in the western corner 

 of the island, have races, species, or even genera restricted to 

 them. 



