XI PALAEONTOLOGY AND EVOLUTION 847 



Many years ago 1 I ventured to speak of the 

 Atlantic mud as &quot; modern chalk,&quot; and I know of 

 no fact inconsistent with the view which Professor 

 Wyville Thomson has advocated, that the modern 

 chalk is not only the lineal descendant of the 

 ancient chalk, but that it remains, so to speak, in 

 the possession of the ancestral estate ; and that 

 from the Cretaceous period (if not much earlier) 

 to the present day, the deep sea has covered a 

 large part of what is now the area of the Atlantic. 

 But if Globigcrina, and Tcrcfa tttt /ti oaput-scrpettiis 

 and Bcryx, not to mention other forms of animals 

 and of plants, thus bridge over the interval 

 between the present and the Mesozoic periods, is 

 it possible that the majority of other living things 

 underwent a &quot; sea-change into something new and 

 strange &quot; all at once ? 



6. Thus far I have endeavoured to expand and 

 to enforce by fresh arguments, but not to modify 

 in any important respect, the ideas submitted to 

 you on a former occasion. But when I come to 

 the propositions touching progressive modifica 

 tion, it appears to me, with the help of the new 

 light which has broken from various quarters, that 

 there is much ground for softening the somewhat 

 Brutus-like severity with which, in 1862, I dealt 

 with a doctrine, for the truth of which I should 

 have been glad enough to be able to find a good 



1 See an article in the Saturdrty Rcviciv, for 1858, on &quot; Chalk, 

 Ancient and Modern.&quot; 



