THE TEETH OF RODENTIA. 373 



tive character in each of the larger groups, and that the 

 variety of structure is constant throughout the members of 

 the same group ; we may take, for example, the Sciuridce, 

 the Huridce, and the ffystrieidce, in each of which the 

 structure of the enamel is different ; and in each is highly 

 distinctive." And further, that the varieties in the struc- 

 ture of the dental tissue, so far as they are known, with a 

 few isolated exceptions, justify and accord with the classifi- 

 cation of the members of the order given by Mr. Waterhouse 

 in his Natural History of the Mammalia. 



