40 



SPINY ANIMALS, 



iostances where a protective coat of spines must bave 

 been acquired quite independently. 



This independent origin is still more clearly indicated 

 ■when we come to the consideration of the hedgehog and its 



:l//, t' 



Vw. 10.— The nedgc'liuy. 



allies, which hear precisely the same systematic relation- 

 ship to the porcupines as is j>resented by the true moles to 

 the mole-voles, as described in our last chapter. That is to 

 say, whereas the hedgehogs and true moles belong to the 

 insectivorous order, the porcupines and the mole-voles 

 are herliivorous rodents. In sjiite, then, of the general 

 similarity of appearance between a hedgehog and a porcu- 

 pine, or, still better, a spiny mouse, we shall find, as 

 already mentioned, that whereas the two latter have the 

 ordinary chisel- like rodent teeth, the former has several 

 narrow and somewhat irregularly-shaped teeth in the 

 front of the j;iws, while its liack teeth are crowned with 

 numerous sharp cusps, instead of having nearly smooth 

 grinding surfaces. A ccordingly, from the purely systematic 

 jjoint of view there is no justification for calling the 



