16 THE MAMMALIA. 



transcribes in his own way with a seemingly unim- 

 portant alteration, which, however, changes the 

 matter itself essentially. He says : ' However much 

 the form of the Kodent may vary to and fro, 

 apparently knowing no boundary, still in the end 

 it is found confined within the general animal 

 type, and must approximate either the one or the 

 other group of animals ; and thus it inclines both 

 to the beasts of prey as well as to Euminants, to 

 apes as well as to bats, and even to other inter- 

 mediate groups.' 



These similarities and parallelisms did not 

 receive much attention until Darwin's day. Darwin 

 himself speaks of convergence only casually, and by 

 way of pointing out the great improbability of its 

 occurrence as the cause of agreements in organisms 

 not related by blood. But for the last ten years 

 or more, zoologists have so often been forced to 

 account for the existence of similarities and agree- 

 ments not as inherited peculiarities of race, but 

 as transformations and assimilations, the result of 

 outward circumstances upon the same or similar 

 original forms that this agency must be taken 

 into consideration, and will be specially necessary 

 in our present inquiry, for it seems to have played 

 no small part in the group of the Mammalia. A 



