Missing Chapters of Geological History. 19 



yield in all sixty-five species, belonging to thirty-one genera; and 

 of them about one-fifth (fourteen in all) pass upwards into the 

 Carboniferous strata. Of the whole 215 Devonian species only 

 eleven are common to Devonian and Carboniferous formations. 



Within the great and important range of the Carboniferous 

 rocks there are, on the other hand, hardly any breaks ; all the 

 important species ranging connectedly throughout, and there 

 being very few extensive and decided indications of want of 

 conformability in the stratification. Professor Ramsay doubt- 

 fully suggests one such break. There may be another ; but it 

 is, at any rate, clear that, on the whole, the deposit was con- 

 tinuous and the interruptions partial. The great coral reefs of 

 the mountain limestone, the coarse sands and grit that suc- 

 ceeded, the alternating bands of clayey mud and vegetable 

 matter of the coal measures — all these seem to point to a long 

 period during which the sea-bottom, at first descending, was 

 afterwards brought by degrees to the state of dry land under- 

 going great and important changes during the period. 



Of more than a thousand species of Carboniferous forms of 

 marine life, scarcely any pass into the Permian rocks ; and of 

 the few that do a large proportion are Brachiopoda. There can 

 hardly be a doubt that a break of time is indicated, as well as 

 a change in the state of the earth's surface. The few Permian 

 plants are different from those of the coal measures; all the 

 fish are distinct from those that abound in the mountain lime- 

 stone ; the whole deposit overlies and overlaps all the older 

 rocks in turn ; and everything helps to tell the same tale. 



But almost immediately — for the Permian series is not very 

 thickly developed in England, and, indeed, hardly deserves the 

 name of series — we come to evidences of another great break, 

 one of the two that divide principal groups of formations. 

 Passing from Permian to the overlying and often conformable 

 New Red Sandstone, we enter the Secondary period : a great 

 mass of evidence proving that here again a very long break in 

 time corresponded to the entire change induced in all forms of 

 life. This evidence, however, is for the most part to be sought 

 for out of England. Professor Ramsay has already, in former 

 communications to the Geological Society, expressed an opinion 

 that the dwarfed character, both of individuals and species, at 

 this critical period of British geology, is the result of a period 

 of cold admitting of the existence of glaciers in our latitude. 

 There seems no new evidence in support of this view ; but it is 

 certain that all the conditions of existence had greatly altered 

 from the time of the coal plants to that when the Labyrinthodon 

 crawled over the sands near Liverpool, and the rock-salt of 

 Cheshire was deposited. 



That, on the whole, the fossils characteristic of the newer 



