THE AMERICAN NATURALIST [Vol. XLYIII 

 TABLE V 



Luzon 40,969 



Mindanao 36,292 



Samar | 5,031 



Negros 4,881 



Panay 4,611 



Palawan 4,027 



Mindoro I 3,851 



Leyte 2,722 



Cebu 1,762 



Bohol 1,441 



Masbate I 1,236 



speciation. Considering the large element of chance in 

 the animal population of a group of islands of such small 

 size as those of the Philippines, where the various islets 

 are at a varying distance from each other, and their 

 faunas have originated from different sources, the rela- 

 tion between their size and the differentiation of their 

 forms is remarkably regular. In Table V, where the main 

 islands have been listed in order of size, with their num- 

 bers of genera and species of mammals, the deer have 

 been excluded entirely, since their generic and specific 

 differentiation is in too chaotic a state to be used. The 

 most striking fact brought out by the table is the lead 

 which the two large islands, Luzon and Mindanao, show, 

 not only in total number of forms, but in index of modifi- 

 cation as well. With the possible exception of Mindoro 

 and Palawan, practically none of the smaller islands is 

 supporting as large a variety of mammalian forms as 

 could be expected of it, a fact which might be explained 

 in a number of ways. 



In all of the tabulations given, the marine mammals 

 have been entirely excluded since the factors affecting 

 their distribution and speciation are so different from 

 those of terrestrial mammals. In the majority of cases 

 marine mammalian families have a paucity both of genera 

 and species, a circumstance brought about by a number 

 of factors. Generally speaking, large, wide-ranging 



