22 DUTCH BORNEO-EXPEDITION. 



and the latest times such as Hugh Low, Everett, White- 

 head and Charles Hose have for years labored with the 

 greatest success in the exploration of Borneo, especially 

 in the north and north-west of the island. 



Although I was able to work in an entirely uninvesti- 

 gated region , ray collections have hardly any new forms 

 of mammals and birds to show ; they go rather to prove 

 that the fauna of the Kapoeas-region is practically iden- 

 tical with that of Sarawak and also of the rest of Borneo. 

 Some mountain forms of mammals and birds, known ori- 

 ginally from the mountain-forests of Sarawak , I found on 

 the Liang Koeboeug, situated south of the Kapoeas plain, 

 though I did not meet them on the much nearer Kenepai. 



As I had no opportunity of visiting mountains of more 

 than 1200 meter in height, it must remain for the pre- 

 sent an open question whether the peculiar high mountain 

 species found at a considerable height on the Kina Balu 

 occur also at similar altitudes in the south. It is , however, 

 not easily conceivable that mountains 2300 meter high, 

 like Mount Raja on the watershed between the Melawi 

 and the Katingan , which latter river flows down towards 

 the south coast, should harbour, if not the same, yet similar 

 forms to those of the over 4000 meter high Kina Balu , 

 the high mountain fauna of which show considerable con- 

 formity to that of the highest peaks of Malakka , Sumatra , 

 Java and even Celebes. These few explanations sufiBce to show 

 that here the vertical almost more even than the horizon- 

 tal difference of certain animal forms is of quite important 

 interest and could be easily employed as demonstration in 

 speculative theories on the periods of rising and sinking 

 of the Malay Peninsula and the Sunda Islands. 



Considered from a geographical standpoint, Borneo 

 belongs to the Malay- Asiatic fauna-region, which also 

 embraces Java and Sumatra with the smaller islands be- 

 longing to them, and the Malay Peninsula and, as has 

 been shown by recent investigations , to a certain extent 

 also the highest peaks of Celebes. Although Borneo has a 



Notes from the Leyden TMuseum, Vol. XIX. 



