CHAPTER VII. 



THE APPARITION AND SUCCESSION OF ANIMAL 

 FORMS. 



TIME was when naturalists were content to take nature as 

 they found it, without any over-curious inquiries as to 

 the origin of its several parts, or the changes of which they 

 might be susceptible. Geology first removed this pleasant 

 state of repose, by showing that all our present species had 

 a beginning, and were preceded by others, and these again 

 by others. Geologists were, however, too much occupied with 

 the facts of the succession to speculate on the ultimate causes 

 of the appearance and disappearance of species, and it re- 

 mained for zoologists and botanists, or as some prefer to call 

 themselves, biologists, to construct hypotheses or theories to 

 account for the ascertained fact that successive dynasties of 

 species have succeeded each other in time. I do not propose 

 in this paper so much to deal with the various doctrines as to 

 derivation and development now current, as to ask the ques- 

 tion, What do we actually know as to the origin and history of 

 life on our planet ? 



This great question, confessedly accompanied with many 

 difficulties and still waiting for its full solution, has points of 

 intense interest both for the Geologist and the Biologist. 

 " If," says the great founder of the uniformitarian School of 

 Geology, " the past duration of the earth be finite, then the 

 aggregate of geological epochs, however numerous, must con- 

 stitute a mere moment of the past, a mere infinitesimal portion 

 of eternity." Yet to our limited vision, the origin of life fades 



