THE BEGINNINGS OF II FE. 615 



viving not only the changes of physical conditions \ 

 but persisting comparatively unaltered, while other 

 forms of life have appeared and disappeared.' 'Such 

 forms,' he says, ' may be termed '■^ persistent types " of 

 lifej and examples of them are abundant enough in 

 both the animal and the vegetable worlds.' He then 

 cites the following examples : — ^ Amongst plants, for in- 

 stance, ferns, club-mosses, and coniferae, some of them 

 apparently generically identical with those now living, 

 are met with as far back as the carboniferous epoch ^ 

 the cone of the oolitic Araucarla is hardly distinguish- 

 able from that of existing species • a species of "Bunts 

 has been discovered in the Purbecks, and a walnut 

 {Juglans) in the cretaceous rocks. All these are types 

 of vegetable structure abounding at the present day; 

 and surely it is a most remarkable fact to find them 

 persisting with so little change through such vast 

 epochs. . . . Every sub-kingdom, of animals yields in- 

 stances of the same kind. The Globlgerlna of the 

 Atlantic soundings is identical with the cretaceous 

 species of the same genus; and the casts of lower 

 Silurian Foraminifera^ recently described by Ehrenberg, 

 assure us of the very close resem.blance between the 

 oldest and the newest forms of many of the Protozoa. . . 

 Amongst the Ctelenterata^ the tabulate corals of the 



^ VkTiick, in accordance with the ' unformatarian view of teiuric con- 

 ditions, so far as geological time is concerned,' he believes to have ' varied 

 within but narrow limits : so that even in Silurian or Cambrian times 

 the aspect of physical nature must have been much what it is now.' 



