24 DUTCH BORNEO-EXPEDITION. 



a close, I would draw attention to a peculiarity which is 

 immediately apparent in glancing over them , viz. the 

 great preponderance of the tree-dwellers. These include 

 not only all the Quadrumana, Chiroptera and all Squir- 

 rels with the exception of the Rheithrosciurus which lives 

 in the mountain forests , but also the numerous species 

 of Tupaias, which form the bulk of the insectivorous 

 mammals of Borneo, and also various Carnivora. Of the 

 68 species of mammals observed and for the most part 

 collected by me , no less than 55 are tree-dwellers. This 

 singular preponderance of tree-dwellers among the mam- 

 mals, which occurs neither in the neighbouring Celebes, 

 nor in Africa nor America in the same latitude, cannot, 

 in the case of Borneo, be due to the presence of animals 

 of prey living on the ground , for, as was mentioned 

 above , these play no role there , and the tiger is even 

 entirely absent. It is much more probable that this cir- 

 cumstance has been influenced in the first place by the 

 forests which cover almost the whole island , and secondly 

 by the vast annual inundations of the immense plains of 

 the Kapoeas-region. 



The birds collected during the expedition will be treated 

 of by myself in the present volume and, if possible, im- 

 mediately follow up Dr. Jentink's treatise on the mammals. 

 For this reason I prefer to postpone the general notes 

 on the Ornis of the Kapoeas-region and to place them at 

 the head of my ornithological paper. 



The collection of reptiles and batrachians is not very 

 large , as but few specimens of this class are to be obtained 

 in the mountain-forests , where a great deal of my time 

 was spent. The same may be said of my fish-collection. 

 As to my stations in the plain, Smitau on the Kapoeas 

 River, which during the dry season probably would be a 

 fine region for collecting reptiles and fishes , was just the 

 contrary during my stay, which was in the rainy season. 

 The most productive stations for these two classes of ani- 

 mals as well as for mollusca , Crustacea , insects and worms 



Notes from the Leyclen ]M.useu.xii, "Vol. XIX^. 



