/S Thomas Henry Miixley 



four-toed Eohippus from the lower Eocene beds. 

 Further discoveries have connected these with the five- 

 toed ancestors of the Tapirs, .and there is the strongest 

 reason to suppose that we now know as nearly as possi- 

 ble the line of ancestry of the horse back to the primi- 

 tive forms common to all the higher mammals. It 

 would, of course, be beyond possibility of proof that the 

 exact fossils described were the actual ancestors of the 

 horse ; but that they are exceedingly close allies of 

 these, and that among them some actual ancestors exist 

 cannot reasonably be doubted. 



Although he had embarked upon geological work 

 with some distaste, Huxley became ver}' closely associ- 

 ated with it as years went on, and indeed, about the 

 seventies, had abandoned his intention to devote him- 

 self specially to ph5'siology, and declared himself to be 

 in the first place a palseontologist. In 1876 he had ac- 

 complished so much that the Geological Society gave 

 him its chief distinction, awarding him the Wollaston 

 Medal in recognition of his services to geological 

 science. He acted as Secretary to the Geological 

 Society from 1859 to 1862, and he was President from 

 1868 to 1870. In 1862, the President being incapaci- 

 tated, Huxley delivered as Deputy-President the Presi- 

 dential Address. This address is famous in the history 

 of geology, because for the first time it stated clearly 

 and in permanent form a doctrine now taken as a first 

 principle in all geological text-books. A large part of 

 geology is the attempt to read the past history of the 

 earth from the evidence given by the successive strata 

 of rocks that form its crust. 



" It is mathematically certain that, in any given vertical linear 

 section of an undisturbed series of sedimentary deposits, the 

 bed which lies lowest is the oldest. In many other vertical 



