THE BEGINNINGS OF LIFE. 623 



by seas. Mr. Darwin says * : c For my part, following 

 out LyelFs metaphor, I look at the geological record as 

 a history of the world imperfectly kept, and written in 

 a changing dialect ; of this history we possess the last 

 volume alone, relating only to two or three countries. 

 Of this volume, only here and there a short chapter has 

 been preserved j and of each page only here and there 

 a few lines/ Such as it is, however, the record seems 

 to show very plainly that there has been nothing ap- 

 proaching to a continuous progression terminating in 

 the Mammalian type. Vertebrata in the form of fishes 

 as high as any existing at the present day, have been in 

 existence since the time when the upper Silurian rocks 

 were deposited. Whilst at different intervening periods 

 in the earth's history, now one, now another of the in- 

 vertebrate forms of life have been in the ascendant, 

 associated, perhaps, with representatives of some highly 

 developed and divergent branch of the vertebrate tree. 

 Till at last as it were accidentally on the top of one 

 of these diverging branches, some of the branchlets per- 

 taining to the quadrumanous order began to undergo 

 modifications which terminated in the evolution of the 

 immediate ancestors of the primeval representatives of 

 our race. 



It is, therefore, illegitimate and unscientific to regard 

 all preceding forms of life as belonging to types lower 

 than our own, or to suppose that they have been the 

 necessary precursors of our advent. 



1 Loc. cit., p. 384. 



