INTRODUCTION. 23 



great many species in common with the districts named , 

 especially with Sumatra, on the other hand a strong pro- 

 pensity to constant deviation is also apparent, a consi- 

 derable number of forms presenting themselves which do 

 not occur elsewhere , while others , e. g. the tiger, so frequent 

 in Malacca , Sumatra and Java , are absent from Borneo. 



We are indebted for a good review of the Mammals of 

 Borneo to the Englishman Charles Hose , who , in the 

 zoological exploration of Sarawak , especially of the Baram 

 valley and the surrounding mountains during a long series 

 of years, has accomplished astonishing results. 



Mr. Hose , in his book on the mammals of Borneo , 

 enumerates 146 species, a great number of which he has 

 himself observed and collected. Several species, for whose 

 occurence no authentic proofs can be furnished , will pro- 

 bably have to be dropped from the list , so that the 

 number of the species thus verified is from 130 to 140. 

 The number of species found by me in the Kapoeas-region 

 amounts to 68 , divided into the various families as follows : 



68 



This number, therefore, is equal to nearly half of all 

 the authenticated species up to the present known from 

 Borneo. As, however, it is not to be supposed that anything 

 approaching all the species which occur in the Kapoeas 

 region were found during my short stay there , the number 

 mentioned above will , later, undoubtedly be very consider- 

 ably increased. 



Before bringing these brief observations on mammals to 



Notes from the Leyden Museum, Vol. XIX. 



