RUDIMENTARY ORGANS. 93 



bones of the horse are in reality the rudiments of the fingers we have 

 represented them to be, and might further demand proof positive 

 of their nature. Fortunately, geology and the science of fossils 

 together come to our aid, with as brilliant a demonstration of the 

 steps and stages of the degradation of the horse's fingers as the 

 most sanguine evolutionist could hope to see. From Mother Earth, 

 whose kindly shelter has sufficed to preserve for us the remains of 

 so many of the forms of the past, we obtain the means for constructing 

 a genealogical tree of the equine race, by methods of certain kind, 

 and through the exhibition of fossils, each bearing an impress of 

 its history, which, to use Cuvier's expression, " is a surer mark than 

 all those of Zadig." 



Our theoretical journey backwards into the ages begins with 

 the Recent or last-formed deposits those which lie nearest the 

 outer surface of our earth. The Recent or Quaternary period 

 forms a division of the Tertiary period that is to say, the latest of 

 the three great epochs into which, for purposes of classifying 

 fossil forms by their relative ages, the geologist divides the rock- 

 formations. The Tertiary rocks, commencing the list, with the last- 

 formed or uppermost strata, begin with the Quaternary or Recent 

 deposits ; next in order succeed the older Pliocene rocks ; then 

 come the Miocene formations, and lastly succeed the Eocene 

 rocks. These last are the oldest of the Tertiary period, and lie in 

 natural order upon the Cretaceous or Chalk rocks, which them- 

 selves belong to an entirely different and anterior (Mesozoic) period 

 in the history of our globe. The youngest or last-deceased of 

 the fossil-horses we meet with, are found in the Quaternary and 

 Pliocene, or the last-formed deposits of the Tertiary system. Between 

 these earlier Pliocene horses and our own Equidae there are no 

 material differences ; and the limbs of these forms may therefore be 

 diagrammatised as depicted in Fig. 34, A, A 1 , and B, B 1 ; the cannon 

 bone in all of these figures being marked a; the splint-bones dd; the 

 "pastern" and " coronary " bone , <r, and the " coffin-bone "/. 



But near the beginning of the Pliocene formations of the Old 

 World, and in the oldest of the Miocene rocks which lie below 

 them, we find a member of the horse family which differs in certain 

 important respects from the horses of the Recent period, and from 

 those of to-day. The fossil horses alluded to are found not merely 

 in Europe, but in the Sewalik Hills in India, and they must there- 

 fore have possessed a very wide range of distribution. When first 

 discovered, M. de Christol called this species of horse Hipparion, a 

 name which has been still retained for it, amidst that constant 

 alteration in zoological nomenclature which is the labour of the 

 foolish and the sadness of the wise amongst us. What are the chief 

 peculiarities of Hipparion ? Briefly stated, in the larger development 



