OF EVOLUTION. 87 



Leidy, has kindly determined for me to be 

 probably the last dorsal and first lumbar. The 

 vertebrae, it will be observed, are of iron, there 

 having been a complete substitution of the bony 

 material by iron-hydroxide (limonite), but with 

 an absolute retention of the structure distinctive 

 of bone. Many of the other bones of the skel- 

 eton were still associated with these vertebrae, 

 but with limited facilities at my command I was 

 only able to procure these two fragments. How 

 old they may be I am not prepared to say ; 

 unfortunately, their geological position was such 

 as not to permit of a clear determination of this 

 point. Apart from the cast of an unknown 

 form of coral found in a neighboring and 

 similarly placed stratum, paleontology furnishes 

 no clue to the solution of this interesting prob- 

 lem. But that the age is very great, the 

 condition of fossilization fully proves; and I think 

 it may be safely held that the vertebrae in ques- 

 tion represent the most ancient, or very nearly 

 the most ancient, remains of man that have thus 



