LES ENCHA1NEMENTS DU MONDE ANIMAL 105 



should be comprised in the direct ancestry of the 

 Horse. They are distinct and parallel branches, 

 which became extinct without leaving descend- 

 ants, and whose hypothetical relations may some 

 day be discovered only by going back to very 

 much earlier periods. Moreover, geological ob- 

 servation positively establishes that there exists 

 no gradual transition between these genera. The 

 last Palceotherium had long, disappeared, without 

 transforming itself, before the first Anchitherium 

 appeared, and this last had in turn vanished, without 

 modification, before it was suddenly replaced by 

 the invasion of the Hipparion. The supposed 

 pedigree of the Equidae is a deceitful delusion, which 

 simply gives us the general process by which the 

 tridactyl hoof of an Ungulate can transform itself, 

 in various groups, into a monodactyl hoof, in view 

 of an adaptation for speed ; but it in no way en- 

 lightens us on the palaeontological origin of the 

 Horse. 



The pedigree of the Bears has been the object, 

 on the part of Gaudry and of Boule, of a study 

 founded on the progressive development of the 

 tuberculous teeth and the correlative reduction of 

 the pre-molars in various types of Tertiary Garni vora. 

 This pedigree begins with the Amphicyon to end 

 in the Bears through the intermediate stages of the 

 Hemicyon of the middle Miocene, of the Hycenarctos 

 of the higher Miocene and Pliocene, and lastly of 

 the existing CE her opus. This series, well enough 

 arranged from the special point of view of the sur- 

 face increase of the tubercules, is certainly inexact 

 so far as real ancestry is concerned. It suffices, 



