20 



THE HORSE 



Pervptychidce of Cope, are found in the Puerco Eocene 

 beds of New Mexico, probably still older than the 

 Wasatch. Forms apparently allied have also been dis- 

 covered by Elitimeyer in early Eocene formations in 

 Switzerland. None of these have been found in such a 

 complete state as Phenacodus ; it is scarcely necessary 

 therefore to dwell upon them here, though it will be 

 well to devote a little time to the consideration of the 

 structure of this form, which, if not in the actual 

 ancestral line of all ungulates (and also, according to 

 Cope, of the insectivores, carnivores, lemurs, monkeys, 

 and even Man himself!), at all events exhibits the 

 primitive pattern upon which the skeletons and teeth 

 of all the others have been constructed, and which has 

 never been departed from in any of them, however dis- 

 guised by the special modifications of particular parts. 



No part of the organisation of an animal is so impor- 

 tant in judging of its general position and characters, 

 and at the same time so perishable, as the brain, 

 and yet in consequence of this organ in all the higher 

 vertebrates being accurately adapted in size and form 

 to the bony case which contains it, we have been 

 able to obtain a wonderfully perfect knowledge of, at 

 all events, the rough anatomy of the brain in many 

 animals which ceased to exist ages ago. A cast of the 

 interior of the skull of Phenacodus, made and figured by 

 Cope, hows a remarkably low type, both as to size and 



