306 TROPICAL NATURE, AND OTHER ESSAYS. 



brought over by uncivilised man, even if any one of them 

 might have been. But there is another reason why they 

 were not so brought over. For on that supposition we 

 should discover remains of fewer and fewer species as we 

 go back into past times till at last when we reached the 

 time of the first occupation of the country by man we 

 should find none at all. But the actual facts are the 

 very reverse of this. For the further we go back the 

 more species of noxious and dangerous animals we dis- 

 cover, till in the time of the palaeolithic (or oldest) 

 prehistoric men, we find remains not only of almost 

 every animal now living, but of many others still less 

 likely to have been introduced by man's agency. Such 

 are the mammoths, rhinoceroses, lions, horses, bears, 

 gluttons, and many others ; and it is equally impossible 

 that these could all have swum across an arm of the sea, 

 which although only about twenty miles wide in its 

 narrowest past, is yet so influenced by strong tides and 

 currents that it becomes as effective a barrier as many 

 straits of double the width. 



Owing, however, to the want of all definite ideas as 

 to the mode by which the earth became stocked with 

 animals and plants, the existence of identical species in 

 countries separated by arms of the sea attracted very 

 little attention till quite recent times. It is probable 

 that Mr. Darwin was really the first person to see the 

 full importance of the principle, for in his Naturalist's 

 Voyage Round the World, he remarks, that " the South 

 American character of the "West Indian mammals seems 

 to indicate that this archipelago was formerly united to 

 the southern continent." Some years later, in 1845, 

 Mr. George Windsor Earl called special attention to the 



