194 THE ORIGIN OF SPECIES 



of tlieir mammalian iuhabitants. Mr. Windsor Earl has 

 made some striking observations on this hi ad, since 

 greatly extended by Mr. Wallace's admirable researches, 

 in regard to the great Malay Archipelago, which is trav- 

 ersed near Celebes by a space of deep ocean, and this 

 separates two widely distinct mammalian faunas. On 

 eit^^ler side the islands stand on a moderately shallow 

 submarine bank, and these islands are inhabited by the 

 same or by closely allied quadrupeds, I have not as 

 yet had time to follow up this subject in all quarters 

 of the world; but, as far as I have gone, the relation 

 holds good. For instance, Britain is separated by a 

 shallow channel from Europe, and the mammals are the 

 same on both sides; and so it is with all the islands 

 near the shores of Australia. The West Indian Islands, 

 on the other hand, stand on a deeply submerged bank, 

 nearl}' 1,000 fathoms in depth, and here we find Ameri- 

 can forms, but the species and even the genera are quite 

 distinct. As the amount of modification which animals 

 of all kinds undergo partly depends on the lapse of 

 time, and as the islands which are separated from each 

 other or from the mainland by shallow channels are 

 more likely to have been continuously united within a 

 recent period than the islands separated by deeper chan- 

 nels, we can understand how it is that a relation exists 

 between the depth of the sea separating two mammalian 

 faunas and the degree of their affinity — a relation which ' 

 is quite inexplicable on the theory of independent acts 

 of creation. f 



The foregoing statements in regard to the inhabitants 

 of oceanic islands — namely, the fewness of the species, 

 with a large proportion consisting of endemic forms— 



i 



