180 (>n the Classification of Mammalia* 



numerous, and exhibit such a diversity of generic forms, that 

 we must conclude from these facts that Edentata have ac- 

 quired, if not the maximum of their development, at least a 

 large portion of it, during the first period of their creation. 



This great development of Edentata, at the presumed dawn 

 of their existence, is in contradiction with the general law 

 which has presided over the development of all other groups 

 of the animal kingdom : each group, each natural order or 

 family, the history of which has been investigated in past 

 times, has manifestly shewn a development parallel to that 

 of the individual life : 1st, An early period, — corresponding to 

 that of youth, — during which the group has but a small num- 

 ber of representatives ; 2c?, A period of full development, — 

 corresponding to that of the adult, — during which the group 

 exhibits the greatest diversity which was in its power to as- 

 sume ; 3d, Finally, there is a period of decline, — correspond- 

 ing to old age and fall, — during which period the individuals 

 are less numerous. In the class of Mammalia there are com- 

 paratively few groups which have thus reached the third 

 period of their history, and passed away from the surface of 

 our earth. The majority have just attained their period of 

 fullest development at the beginning of the human era, and 

 are actually in existence upon the external surrounding crust 

 of our planet. 



According to these facts, and satisfied that the systematic 

 position which we have assigned to Edentata is natural, and 

 in accordance with the general plan of the creation, we pre- 

 dict that remains of Edentata will be found in the strata be- 

 low the miocene ; that they will be found in secondary beds 

 at least as low as the oolite, if not further down. If they 

 prove to be of a decidedly lower zoological grade than Mar- 

 supialia, they must have been introduced on earth before the 

 latter ; and if parallel with them, they must have been con- 

 temporaneous. In the actual era, the order of Edentata is in 

 its period of decline : its representatives now living are much 

 less numerous than the extinct ones already known. 



§ 3. The Pachydermata constitute another group, whose 

 history chiefly belongs to past times. They are known to 

 have existed as early as the eocene period ; the miocene is 

 the period of their greatest development ; they diminish in 



