104 THE TRANSFORMATIONS OF THE ANIMAL WORLD 



development of the nasal bones and of the frontal 

 and nasal horns in the Rhinoceroses, and that of the 

 antlers in the Cervidse, have all been taken in their 

 turn as guiding lines in the establishing of the 

 concatenations to which has been accorded the value 

 of natural series, the various terms of which are 

 related by way of descent. 



This method certainly presents the greatest 

 dangers. It leads, in fact, to the confusion of the 

 real evolution of a natural group of fossil animals 

 with what is, in effect, only the functional evolution 

 of an organ in a series of genera belonging to different 

 natural branches and having no direct relationship. 

 Two examples of these series which have become 

 classical and we consider as artificial and inexact, 

 namely, that of the Equidae and that of the Ursidse, 

 will make this demonstration clear. 



The ancestry of the Equidaa has been studied, 

 at the same time by Huxley and Kowalevsky in 

 Europe, and by Marsh and Cope in America. We 

 will, here, only examine the European series ; this 

 series, starting from the Palceotherium and from the 

 Paloplotherium^ comes down to the horse by the 

 intermediary of the Anchitherium and of the Hip- 

 par ion. These genera form, in fact, a very re- 

 markable series nearly always cited as a classical 

 example of evolution from the point of view of 

 the gradual atrophy of the second and fourth toes 

 and of the definitive predominance of the third toe 

 in the solipedal hoof of the Horse. Yet, Mdme. 

 Pavlow, and Schlosser and Weithofer as well, have 

 proved that neither the Palceotherium nor the 

 Hipparion I readily add nor the Anchitherium 



