m LECTURES ON EVOLUTION 129 



gether, or for their scientific importance, to the 

 series of fossils which he has deposited there. 

 This vast collection has yielded evidence bearing 

 upon the question of the pedigree of the horse 

 of the most striking character. It tends to show 

 that we must look to America, rather than to 

 Europe, for the original seat of the equine series ; 

 and that the archaic forms and successive modifi- 

 cations of the horse's ancestry are far better 

 preserved here than in Europe. 



Professor Marsh's kindness has enabled me to 

 put before you a diagram, every figure in which is 

 an actual representation of some specimen which 

 is to be seen at Yale at this present time 

 (Fig. 9). 



The succession of forms which he has brought 

 together carries us from the top to the bottom 

 of the Tertiaries. Firstly, there is the true horse. 

 Next we have the American Pliocene form of the 

 horse (PlioJiippus) ; in the conformation of its limbs 

 it presents some very slight deviations from the 

 ordinary horse, and the crowns of the grinding 

 teeth are shorter. Then comes the Protohippus, 

 which represents- the European Hipparion, having 

 one large digit and two small ones on each foot, 

 and the general characters of the fore-arm and leg 

 to which I have referred. But it is more valuable 

 than the European Hipparion for the reason that 

 it is devoid of some of the peculiarities of that 

 form peculiarities which tend to show that the 



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