186 CRITIQUES AND ADDRESSES. [ix. 



found fossilized in the white chalk. The Globigerince, 

 Cyatholiths, Coccospheres, Discoliths in the one are abso- 

 lutely identical with those in the other ; there are iden- 

 tical, or closely analogous, species of Sponges, Echino- 

 derms, and Brachiopods. Off the coast of Portugal, 

 there now lives a species of Beryx, which, doubtless, 

 leaves its bones and scales here and there in the 

 Atlantic ooze, as its predecessor left its spoils in the 

 mud of the sea of the Cretaceous epoch. 



Many years ago 1 I ventured to speak of the Atlantic 

 mud as " modern chalk," and I know of no fact incon- 

 sistent 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 Globi- 

 gerina, and Terebratula caput-serpentis and Beryx, 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 "sea-change into something 

 new and strange " 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 modification, 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 



1 See an article in the Saturday Revicic, for 1858, on "Chalk, Ancient and 

 Modern." 



