436 Geology of 



However, speaking of the principle itself, I wish to point out, if we 

 were to decide from a few isolated species in two distant countries 

 which show some or even a close resemblance to each other, that these 

 countries must hare once been connected in some way, we should in 

 many instances form erroneous conclusions. "VTe might as well say, 

 that because there are struthious birds in Australia, the Malay 

 Archipelago, Africa, America, and Asia, all these countries have been 

 connected with Xew Zealand, or because marsupial remains have been 

 found in secondary rocks in Europe and several species of opossums 

 are living in America, these countries had also been united with 

 Australia. 



Speaking from a general point of view, I wish to add, that the attempts 

 to trace the geographical relations of the fauna and flora of a country 

 can easily be exaggerated, and thus a theory be ridden to death which 

 otherwise would be very useful. Can the explanation of any specific 

 resemblance in two distant countries not be found in many instances at 

 least, in the adoption of more simple natural causes, such as the trans- 

 port by icebergs, or on floating islands, by birds, etc., and of which Sir 

 Chas. Lyell, in his great work, the " Principles of Geology," gives many 

 striking instances ? However, where the theory of land connection is not 

 admissible, and where also others, which have hitherto been applied, fail, 

 might we not assume that similar climatic and other physical conditions 

 could produce similar specific characters under the great law of 

 evolution ? It is a most difficult problem to say what constitutes a 

 species, and therefore might it not be safer to believe until the 

 impossibility of such an hypothesis has been demonstrated satisfactorily, 

 that there exists a similitude as well as an identity of species under 

 certain given conditions. In one word, might we not throw out the 

 conjecture that in two more or less distant countries which never 

 were directly united, some forms of organic life can and do exist, 

 which show what to us appears identical specific characters, because 

 the cause or causes of their evolution were identical or nearly 

 identical, and thus a considerable number of supposed changes in the 

 level of many countries of which we do not find geological records,, 

 can be dispensed with. It is true, that instances to be explained by 

 the migration or accident theories are of more frequent occurrence 

 and more easily proved, but I think it would be just as interesting, 

 where these cannot be admitted, to trace in all its bearings the 

 similitude of species in distant countries. This view would, at least, 

 open up a field of fresh research, and afford a new illustration and 

 confirmation of the great theory of evolution. 



