THE EOZOIC AGES. 33 



profusion and gi-andeur unequalled in the periods 

 whose flora is known to us. 



But while Eozoon thus preaches of progress and of 

 development, it has a tale to tell of unity and same- 

 ness. Just as Eozoon lived in the Laurentian sea, 

 and was preserved for us by the infiltration of its 

 canals with siliceous mineral matters, so its suc- 

 cessors and representatives have gone on through all 

 the ages accumulating limestone in the sea bottom. 

 To-day they are as active as they were then, and are 

 being fossilised in the same way. The English chalk 

 and the chalky modern mud of the Atlantic sea-bed, 

 are precisely similar in origin to the Eozoic lime- 

 stones. There is also a strange parallelism in the fact 

 that in the modern seas Foraminifera can live under 

 conditions of deprivation of light and vital air, and 

 of enormous pressure, under which few organisms 

 of greater complexity could exist, and that in like 

 manner Eozoon could live in seas which were perhaps 

 as yet unfit for most other forms of life. 



It has been attempted to press the Eozoic Forami- 

 nifers into the service of those theories of evolution 

 which would deduce the animals of one geological 

 period by descent with modification from those of 

 another ; but it must be confessed that Eozoon proves 

 somewhat intractable in this connection. In the first 

 place, the creature is the grandest of his class, both 

 in form and structure; and if, on the hypothesis of 

 derivation, it has required the whole lapse of gfO' 

 logical time to disintegrate Eozoon into Orbulma, 



D 



