I. 



ON THE LAW WHICH HAS REGULATED 

 THE INTRODUCTION OF NEW SPECIES.* 



Geographical Distribution dependent on Geologic 

 Changes. 



EVERY naturalist who has directed his attention to 

 the subject of the geographical distribution of animals 

 and plants, must have been interested in the singular 

 facts which it presents. Many of these facts are quite 

 different from what would have been anticipated, 

 and have hitherto been considered as highly curious, 

 but quite inexplicable. None of the explanations 

 attempted from the time of Linnseus are now 

 considered at all satisfactory ; none of them have 

 given a cause sufficient to account for the facts 

 known at the time, or comprehensive enough to 

 include all the new facts which have since been, and 

 are daily being added. Of late years, however, a 

 great light has been thrown upon the subject by 

 geological investigations, which have shown that the 

 present state of the earth and of the organisms now 



* Written at Sarawak in February, 1855, and published in 

 the " Annals and Magazine of Natural History," September, 

 1855. 



B 



