18 ON THE BORNEAN ORANG-OETAN. 



constant ; there is an endless variation in tinge , from 

 light red to dark brown-red , independent from age or sex 

 or habitat; the nail on the thumb of the hind feet is pre- 

 sent or wanting as well in red as in dark colored indivi- 

 duals; and the peculiarities of the skull are the most 

 puzzling of all, no two skulls of the same age are alike, 

 there is an endless variation of development in prognatism, 

 in form , state of excavation and extension of the bony 

 palate, in length of nasalia, in shape, size and position 

 of the orbits , in development of the crista, which often is very 

 prominent in small skulls, much less prominent or not 

 present in large skulls , in size and shape of the lower jaw 

 especially of its posterior half. And with all other charac- 

 teristics it is always the same thing , f. i. with the length 

 of the fur a, s. o., everywhere a very surprising incon- 

 stancy. In this point it is like in the human beings, no 

 two persons are exactly alike. The reason for the Bornean 

 Orang-oetan is perhaps this: that there are in Borneo no 

 large carnivorous animals , no ennemies to throw obstacles 

 in the way of their existence, in one word there is no 

 struggle for life , by which they would be forced to a 

 development in a certain direction; they live more or less 

 all under the same conditions, the equator crossing the 

 middle of the island. 



Notes from the Leyden Museum, Vol. XVII. 



