270 THE MAMMALIA. 



and possessing pointed, tuberculate molars, they 

 point to the Insectivora. For another circumstance 

 to be considered is, that various peculiarities in the 

 teeth of the lower Canidae show approximation to 

 the dentition of the Insectivora ; and the occurrence 

 of rudimentary clavicles and the rudiment of a 

 fifth toe on the hind limb, also clearly point to 

 ancestors with well-developed clavicles, and the full 

 number of five toes. All this is found united in 

 the Insectivora : hence our present dogs have been 

 traced back to the Eocene and Pre-Eocene Insect- 

 eaters with certain peculiarities of the Marsupials. 

 This derivation of the Dog tribe which is based 

 mainly upon deductions from the present nature 

 and distribution of the group goes back, therefore, 

 into that dim twilight which, in the opinion of 

 Cuvier and his followers, could alone precede the 

 dawn of true light in the mammal world. We 

 shall have to dwell a little in this Eocene period 

 and look around among the incredible wealth of 

 mammal forms, which seem, as it were, to have been 

 re-animated by Filhol's graphic descriptions (see 

 above, p. 64). We shall obtain some idea of the 

 vigour of that exuberant, plastic life if, in place of 

 the few Carnivora that are now inhabiting France, 

 and indeed Southern and Central Europe, we ima- 



