2G6 



THE MAMMALIA. 



In now returning to the living Canidse, several 

 species demand our attention, one of which is 

 described as Icticyon venations, a native of Brazil, 

 the other under the generic name of Cyon, inhabit- 

 ing the countries to the north and north-east of the 

 Altaian mountains. These dogs do not possess the 

 third molar in the lower jaw, and the m in the upper 

 jaw is so small that a reduction appears to be immi- 



FIG. 49. Lower Jaw of Icticyon. After Huxley. 



nent there as well. It is in the natural course of 

 things that one or both of the first premolars, or 

 the last molar, should become useless and forced to 

 disappear, by the neighbouring teeth being specially 

 taken into requisition, although in most cases we 

 do not know the immediate reason of this. 1 The 



1 Any of our readers who can examine the head of a dachs- 

 hund may convince themselves of the fact that the first pre- 

 molar above and below can scarcely be of any use to the animal ; 



