S4 THE MAMMALIA. 



of the existing animal forms the nearer we come 

 to their origin. In cases where to-day no connec- 

 tions seem to exist except the characteristics of the 

 class and order, in going hack \ve find more definite 

 and ever clearer resemblances, till finally the com- 

 mon original forms are discovered. These have 

 often been called ' mixed forms,' which term, how- 

 ever, does not properly indicate the nature of the 

 matter. For in most cases the question is much less 

 about a combination of marked characteristics which, 

 in earlier times were, and at present are distributed 

 over different branches, than about a still undifferen- 

 tiated basis that has in various directions proved 

 itself transformable. For instance, the Hoofed 

 Animals, which when first met with are unfortu- 

 nately already very marked in character, possess 

 the full number of toes and a good supply of teeth. 

 Of the teeth it might indeed be said that they show 

 a ' mixed character/ inasmuch as the front ones 

 arc more adapted for attack and defence, while the 

 are specially adapted for munching vegetable 

 substances. But if the earliest forms of Hoofed 

 Animals and the earliest forms of Carnivora point 

 to animals resembling the Insectivora in structure 

 and form, as their common ancestors, and these 

 again point to the Marsupials, we can assuredly 



