Chap. XIII]. MAMMALS ON OCEANIC ISLANDS. 186 



of their mammalian inhabitants. Mr. Windsor Earl 

 has made some striking observations on this head, since 

 greatly extended by Mr. Wallace's admirable researches, 

 in regard to the great Malay Archipelago, which is 

 traversed near Celebes by a space of deep ocean, and 

 this separates two widely distinct mammalian faunaa 

 On either side the islands stand on a moderately shal- 

 low 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 AustraUa. The West Indian Islands, on the 

 other hand, stand on a deeply submerged bank, nearly 

 1000 fathoms in depth, and here we find American 

 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 afiinity, — a relation 

 which is quite inexplicable on the theory of independ- 

 ent acts of creation. 



The foregoing statements in regard to the inhabi- 

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

 species, with a large proportion consisting of endemic 

 forms — the, members, of certain groups, but not those of 



