CHAPTEE XII. 



ANCESTRY AND CLASSIFICATION. 



IN the history of human life nothing is more 

 apparent than that individuals are born and 

 perish, while families survive ; families die out, 

 while nations continue to exist ; nations also 

 have their limits, and mankind outlives them. 



It is the same in the past history of life in gen- 

 eral, revealed to us in the stony book of nature. 

 Species come and go, while genera still maintain 

 their ground ; and, in their various times, genera, 

 families, and orders of animals appear and disap- 

 pear, while the groups higher than they outlive 

 them. From this it follows that the existing 

 members of any group are but the merest frag- 

 ment of its true whole ; and yet it is in large 

 measure from this fragment that we must deduce 

 the true character and relations of the group, as 

 well as its past history. Nowhere is this more con- 

 spicuous than in the butterflies. There are prob- 

 ably at least ten thousand species now living ; 

 countless myriads must have enlivened the face of 

 nature in past ages ; yet only a dozen have been 

 found in a fossil state ; and these fossil remains 



