INTRODUCTION. 21 



After my return to Europe my Assistant Moret did, 

 during the months of August, September and October, 

 some collecting work in the valley of the Ketoengau River 

 and visited for a second time Mount Kenepai , and during 

 the three following months he made a small collection at 

 Poutianak. 



This , briefly, is a picture of my zoological field of labor 

 which covered only the district of the Upper Kapoeas. As 

 the opportunity which we had of travelling in this part 

 only seldom offers , 1 considered it desirable to take the 

 utmost possible advantage of it, instead of devoting part 

 of the time to the coast-region and the lower reaches of 

 the river which , moreover, have been often visited. 



The result of this limitation of my field of labor is , it 

 is true, that numbers of animals which occur only near 

 the sea-coast do not figure in my collections. This void is 

 especially noticeable in the department of ornithology. In 

 my collections there are, for example, hardly any of the 

 numerous species of waders and water-birds, among them 

 many migratory birds from the north of Eastern Asia 

 which are accustomed to take up their winter quarters in 

 the great lower river-reaches and coast districts. A stay 

 of two or three weeks would have sufficed to enrich my 

 collections with at least fifty species of which I have now 

 no specimens. 



It is unfortunately not yet possible for me to give a 

 review of the zoological results of the journey or to draw 

 any conclusions whatever from the same. The greater part 

 of the material is still awaiting its elaboration; some groups 

 have been commenced with ; at present , however, only the 

 mammals, birds and mollusca are so far arranged and 

 defined that an idea of the respective local fauna can be 

 obtained. As regards the two first-named classes, Borneo 

 can be reckoned at present as one of the best known 

 islands of the East-Indian Archipelago. Apart from the 

 earlier investigations of S. Muller, Schwaner, Croockewit, 

 Semmelink, Diard, Wallace and many others, men of later 



Notes from tlie Leyden IMuseuin, "Vol. XIX. 



