RISE AND FALL OF BYGONE RACES 21 



earth and water worms. Through each of these six 

 divisions there runs an air or theme, of which the 

 animals themselves are the innumerable variations 

 or fugal developments. 



Amongst the members of each of these principal 

 groups we find one dominant tendency — to possess 

 the earth. Having realised this, they are in turn 

 replaced by others, so that if by the aid of fossils we 

 look at the history of vertebrate life, we find as we 

 recede further and further from the present that in 

 the order of their supremacy animal groups suffer 

 eclipse. First, all traces of man disappear ; then at a 

 still greater distance of time the mammals and birds 

 vanish ; another stage further back and the reptiles, 

 hitherto so abundant, are no longer found ; whilst 

 in a still more ancient time the newts die away, 

 leaving only fish of a few kinds analogous to our 

 sharks and to the garpike of American lakes. At 

 the most remote epoch of which we have any recog- 

 nisable animal records, no vertebrates are found 

 amongst them. 



From invertebrate beginnings we find fish de- 

 veloping into a multitude of forms, peopling the rivers 

 and lakes by immigration from the sea, to which 

 many return, as to their true home, when their life 

 is ending. From the ancient armoured types to 

 lamprey and shark and bony fish, each division becomes 

 more and more complex and highly organised as 

 its dominion increases and its circumstances improve, 

 and remains simple if its life remains uniform. 



