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which bear, in a close and important manner, upon the differences between the 

 productions of various regions, and shows how barriers of any kind which 

 prevent free migration, favour, — under the operation of the laws which he 

 proceeds to point out and elucidate — -the production of organisms presenting 

 marked differences from each other, without destruction of those general 

 affinities, which the same species (using this term in the sense now applied to it 

 by advanced systematists) present at different points and stations. 



In like manner, Sir Charles Lyell, in the last edition of his " Principles 

 of Geology " calls special attention to the geographical distribution of species, 

 and to the causes which affect it, and I cannot do better than quote some 

 passages from that work also. And here I may say, that I have the less 

 hesitation in using extracts from the writings of such authors as Darwin and 

 Lyell, because it would be impossible for me to convey in more clear and 

 apposite language, the matters involved in these extracts. 



Sir C. Lyell says, " Although in speculating on ' philosophical possibilities,' 

 said BufFon, writing in 1755, the same temperature might have been expected, 

 all other circumstances being equal, to produce the same beings in different parts 

 of the globe, both in the animal and vegetable kingdoms, yet it is an undoubted 

 fact, that when America Avas discovered, its indigenous quadi-upeds were all 

 dissimilar to those previously known in the Old World. The elephant, the 

 rhinoceros, the hippopotamus, the cameleopard, the camel, the dromedary, the 

 buffalo, the horse, the ass, the lion, the tiger, the apes, the baboons, and a 

 number of other mammalia, were nowhere to be met with on the new con- 

 tinent ; while in the old, the American species, of the same great class, were 

 nowhere to be seen — the tapir, the lama, the pacari, the jaguar, the couguar, the 

 agouti, the paca, the coati, and the sloth. 



" These phenomena, although few in number, relatively to the whole 

 animate creation, were so striking and so positive in their nature, that the 

 great French naturalist caught sight at once of a general law in the geographical 

 distribution of organic beings, namely, the limitation of groups of distinct 

 species to regions separated from the rest of the globe by certain natural 

 barriers. It was, therefore, in a truly philosophical spirit that, relying on the 

 clearness of the evidence obtained respecting the larger quadrupeds, he ventured 

 to call in question the identifications announced by some contemporary natural- 

 ists, of species of animals said to be common to the southern extremities of 

 America and Africa. 



" In order to appreciate the importance and novelty of the doctrine, that 

 separate areas of land and water were the abodes of distinct species of animals 

 and plants, we must look back to the times of Buffon and see in what crude 

 conjectures even so great a naturalist as his illustrious contemporary Linnaeus 

 indulged, when speculating on the manner in which the earth may first have 

 become peopled with its present inhabitants. The habitable world was imagined 

 by the Swedish philosopher to have been for a certain time limited to one small 

 tract, the only portion of the earth's surface that was as yet laid bare by the 

 subsidence of the primeval ocean. In this fertile spot the originals of all the 

 species of plants which exist on this globe were congregated together with the 

 first ancestors of all animals and of the human race. 'In qua commode 

 habitaveurit animalia omnia, et vegetabilia lcete germinaveruit. ' In order to 

 accommodate the various habits of so many creatures, and to provide a diversity 

 of climate suited to their several natures, the tract in which the creation took 

 place was supposed to have been situated in some warm region of the earth, 

 but to have contained a lofty mountain range, on the heights and in the 

 declivities of which were found to be all temperatures and eveiy climate, from 

 that of the torrid to that of the frozen zone. There are still perhaps some 

 geologists who adhere to a notion once very popular, that there are signs of a 



