HI LECTURES ON EVOLUTION 131 



European Hipparwn is rather a member of a 

 collateral branch, than a form in the direct line of 

 succession. Next, in the backward order in time, 

 is the Miohippus, which corresponds pretty nearly 

 with the Anchitherium of Europe. It presents 

 three complete toes one large median and two 

 smaller lateral ones ; and there is a rudiment of 

 that digit, which answers to the little finger of the 

 human hand. 



The European record of the pedigree of the horse 

 stops here ; in the American Tertiaries, on the 

 contrary, the series of ancestral equine forms is 

 continued into the Eocene formations. An older 

 Miocene form, termed Mesohippus, has three toes 

 in front, with a large splint-like rudiment repre- 

 senting the little finger; and three toes behind. 

 The radius and ulna, the tibia and the fibula, are 

 distinct, and the short crowned molar teeth are 

 anchitherioid in pattern. 



But the most important discovery of all is the 

 Orohippus, which comes from the Eocene formation, 

 and is the oldest member of the equine series, as 

 yet known. Here we find four complete toes on 

 the front limb, three toes on the hind-limb, a well- 

 developed ulna, a well-developed fibula, and short- 

 crowned grinders of simple pattern. 



Thus, thanks to these important researches, it 

 has become evident that, so far as our present 

 knowledge extends, the history of the horse-type 

 is exactly and precisely that which could have been 



K 2 



