371 



not swarm in the forests of New Giiinca as well as 

 in tliose of Bonieo and Malacca. "We can liardly help 

 coiicluding, therefore, that some other law has regii- 

 lated the distribution of xiesting species than the phy- 

 sical conditions of the countries in which thsy are found, 

 or we sliould not see countries the most opposite in cha- 

 racter witli simiUir productions, whilc others almost 

 exactly alike as respects climate and general aspect, 

 yet diifer totally in their forms of organic life. 



In a former Number of this periodical we ende- 

 avoured to show that the simple law, of every new 

 creation being closel}' allied to some species already 

 existing in the same country, would explain all these ano- 

 malies, if taken in conjunction with the clianges of 

 surface and the gradual extinction and introduction of 

 species, whicli are facts proved by geology. At the 

 period when New Guinca and North Australia were 

 united, it is probable that their physical features and 

 climate were more similar, and that a considerable 

 proportion of the species inhabiting each portion of the 

 country were found over the wliole. After the separa- 

 tion took place, we can easily understand how the 

 climate of both might bc considerably modified , and 

 this might perhaps lead to the extinction of ccrtain 

 species. During the period that has since elapsed, 

 new species have been gradually introduced into each, 

 but in each closely allied to the pre-existing species, 

 raany of which were at first common to the two coun- 

 tries. This process would evidently produce the pre- 

 sent condition of the two faunas, in which thcre are 

 many allied species, — few identical. The grcat well- 

 marked groups absent froni the one would nccessarily 



