174 



THE GENESIS OF SPECIES. 



[Chap. YII. 



(r. 



enetic affinity, it would b(^ rash to affirm dogmatically 

 that there is any impossii)ility in the independent origin 

 of such forms as centetes aiul solenodon, or of genetically 

 distinct hatrachians, as similar to each other as are some 

 of the frogs of South America and of Europe. At the 

 same time, such phenomena must at present be con- 

 sidered as very improbable, from the action of ancestral 

 habit, as l)eftire stated. 



AVe have seen, then, that the geographical distribution 

 of animals presents dithculties, though not insuperable ones, 

 for the Darwinian hypothesis. If, however, other reasons 

 against it seem to have any weight — if, especially, there 

 is reason to believe that geological time has not been 

 sufficient for it, then it will be well to bear in mind the 

 facts here enumerated. These facts, however, are not 

 opposed to the doctrine of evolution ; and if it could be 

 established that closely similar forms had really arisen 

 in complete independence one of the other, they Avould 

 rather tend to strengthen anrl to support that theory. 



