138 EXTINCT SPECIES. 



The geologist's notion of the word 6 recent' comprehends 

 a span of time, of beginning so remote that the oldest records 

 of human history fade to insignificance by comparison. Since 

 this world of ours acquired its final surface settlement, so to 

 speak, numerous species have become extinct. The process 

 of exhaustion has gone steadily on. It has been determined 

 by various causes some readily explicable, others involved in 

 doubt. The fact is well established, for example, that all 

 Northern Asia was at one time, not geologically remote, over- 

 run by herds of mammoth creatures, which, as to size, dwarf 

 the largest elephants now existing ; and which, among other 

 points distinguishing them from modern elephants, the 

 mammoths were covered by a crop of long hair. Very 

 much of the ivory manufactured in Kussia consists of the 

 tusks of these now extinct mammoths, untombed from time 

 to time. 



Tilesius declares his belief that mammoth skeletons still 

 left in Northern Russia exceed in number all the elephants 

 now existing upon the globe. Doubtless the process of mam- 

 moth extinction was very gradual, and extended over an enor- 

 mous space of time. This circumstance is indicated by the 

 varying condition in which the tusks and teeth are found. 

 Whereas the gelatine, or soft animal matter, of many speci- 

 mens remains imparting one of the characteristics necessary 

 to the being of ivory other specimens have lost this material^ 

 and mineral substances, infiltrating, have taken its place. The 

 gem turquoise is pretty generally conceded to be nothing else 

 than the fossilised tooth of some extinct animal probably the 

 mammoth. 



Curiosity of speculation prompts the mind to imagine to 

 itself the time when the last of these gigantic animals suc- 

 cumbed to influences that were finally destined to sweep them 

 all from earth. Had men come upon the scene when they 

 roamed their native wilds f Were those wilds the same as 

 now, as to climate and vegetable growths? Testimony is 



