554 



THE AMERICAN NATURALIST [Vol. XLV 



This difference is noticeable among- the fishes above all 

 others. On the other hand, the difference is less among 

 the birds, and the opposite holds for land and fresh- 

 water molluscs whose number is reckoned by the Sar- 

 asins for Sumatra as 129 species; Borneo, 311; Java, 

 ,233, and Celebes, 238. 



Weber explains the poverty of fauna in this manner : 

 that Celebes, as we understand it to-day, has not long 

 been in its present condition, but rather that it was 

 formed by the uniting of a number of small islands 

 which, as is always the rule in such cases (especially 

 among the fresh-water fishes) possess a sparse or poor 

 fauna. In this same wise is it made evident why the 

 fresh-water mussels (Unionidffi) which occur upon the 

 continent of Asia and Australia, and upon the Greater 

 Sunda Islands, are lacking on Celebes. Yon Martens 

 comes to this same conclusion, that they (along with 

 other generally distributed families of fresh-water mol- 

 luscs) do not occur upon small islands. They are want- 

 ing thus upon the Moluccas and on Celebes, where the 

 entire fauna has been made up by the merging together 

 of those of several smaller islands to form a single one. 



The opinion of the Sarasins is somewhat different 

 from the explanation, of Weber. They are of the opin- 

 ion, brought forward as especially important, that be- 

 tween the different parts of the island ancient faunistic 

 differences are demonstrable, a peculiarity of the fauna 

 of Celebes which has been thoroughly investigated by 

 them. The Sarasins have taken this up especially from 

 the point of view of distribution of land and fresh-water 

 molluscs. Von Martens had already noticed that north 

 and south Celebes possessed hardly a single species of 

 mollusc in common ; and the Sarasins made evident that 

 there existed an easterly mollusc fauna, besides a well- 

 differentiated fauna in the great lakes of central Celebes. 

 Other animals exist, divided from each other in this same 

 manner. So among the mammals, the Babirusa and the 

 crested baboon, Cynopithecus, are found in the northern 



