MOLES AND THEIE, LIKE. 25 



CHAPTER III. 



MOLES AND THEIR LIKE. 



It is probaLly well known to most of our readers that in 

 tlie evolution of organized nature two great factors have 

 constantly been working against each other — the one being 

 the adherence to a particular type of structure, while the 

 other is the adaptation to a special mode of life. The 

 usual resultant of these two forces has been that, in any 

 assemblage of animals specially adapted for a certain 

 peculiar kind of existence, while internally its different 

 members have preserved their essential structural 

 peculiarities more or less intact, externally they have 

 become so much like one another that it often recpiires 

 the aid of the professed zoologist to point out their 

 essential distinctness. Perhaps in no case is this adaptive 

 similarity in external characters better displayed than 

 among certain of the smaller mammals which have taken 

 to a more or less completely subterranean burrowing 

 existence, of which the common mole is the best known 

 example. In the British Islands we have, indeed, only 

 this one creature which has adojjted this particular mode 

 of life ; and it is to this animal alone that the name 

 " mole " projjerly belongs. Other jjarts of the world 

 pjossess, however, sevei'al more or less closely allied animals 

 to which the same name must clearly be also applied. If, 

 however, we happen to have friends from the Cape, we 

 may hear them applying the name " moles " to certain 

 burrowing mammals from that district, which upon exami- 

 nation would be found to differ essentially in structure 

 both from the ordinary moles and from one another. 

 Then, again, if we were to travel in Afghanistan or some 

 of the neighbouring regions, we should meet with another 

 mole-like burrowing animal to which we should likewise 

 feel disjaosed to apply the same name, although it has not 



