FOSSILS. 71 



hind enough extinct entombed forms to enable 



sit to be recognised by their remains, 



the grea ;sil remains is not so much 



survival and persistence upon the 

 earth of the life which has once existed. The 

 natural inf< would be that the variety in 



kinds of life has been steadily diminishing from 

 the time, < > inct 



IpS of plants and animals. But with each 



ip of newer st enera and families of 



ani:: with among the fossils, which 



Ot known in the old' of f"ssiis. 



erhaps n f that they were pre- 



ent from the earth; and it is possible 



that f them may have come into existence 



- of tlu- types which were already 

 in ei 



1 as the 

 ' nee, 



e w Inch affects the history 



of life, which :. that new modifications 



d animals should constantly come into 



nder the varying conditions which the 



rhe different organic 



typ< d from extinction by manifesting 



ptation to altered 1 ircum- 



iperty which enables the 

 genus to survive from the earliest times. It 

 undergoes - of ch y which slight 



differences of form or ornament are perpetuated 

 for a time, eventually giving place to another 

 similar f modifications; and these char- 



acters distinguish the species of which the genus 

 consists. Even persons who are not trained to 



