rNTRODUCTION. 65 



the foregoing conditions have ceased to exist, or 

 have removed to higher temperatures, the horse alone 

 has remained to the present time in the same regions, 

 without, it would appear, any protracted interrupt 

 tion ; since, from the circumstances which manifest 

 deposits to be of the earliest era in question, frag- 

 ments of its skeleton continue to be traced upwards 

 in successive formations, to the present superficial and 

 vegetable mould. 



Moreover, the bones of Equidse, in all their 

 localities, agree sufficiently, at least so far as our 

 researches extend, to fix the stature of the animals 

 at or near the standard of the wild horses of 

 Asia, and the middle-sized unimproved breeds of 

 the present day; while nearly all the others, and 

 particularly those of Ruminants, found in the same 

 deposits, often announce structures considerably 

 larger than their present congeners. Now, as 

 the debris of Mastodons, Elephants, Bovidse and 

 Cervidas, have likewise been discovered in the 

 western continent, but it would seem without those 

 of the horse, or the hysena, it appears that neither 

 were at any time indigenous, while in the old con- 

 tinent, both are found ; one having only retreated 

 to a southern latitude, and the other continuing to 

 reside without, or with no sensible difference of 

 characters, in its primeval location : as if, while 

 several very remarkable species of animals have dis- 

 appeared, and others are now only extant in climates 

 of higher temperature, the horse alone had escaped 

 the operation of some great agency in nature, which 



E 



