OF CREATION. 59 



date as the old red sandstone ; a view which has since 

 been verified beyond the possibility of question by 

 the discovery, in Kussia, of two series one resem- 

 bling our old red sandstone conglomerate, and the 

 other our devonian gritty and 'slaty beds both evi- 

 dently belonging to one period both fossiliferous, and 

 each containing fossils, by which the identity of these 

 rocks with the beds of our own country, both in De- 

 vonshire and Scotland, is placed beyond doubt. 



In Belgium, and in other parts of Europe, the pas- 

 sage from the silurian rocks to those of newer date is 

 perfectly unbroken ; and even in Wales it is not easy, 

 nor is it always possible, to distinguish so accurately 

 between the two as to state where the lower series 

 terminates, and which is to be considered the lowest 

 member of the overlying group. 



The line of demarcation between these strata be- 

 ing thus slightly marked in some places, the naturalist 

 is enabled to trace the gradual transition of the ani- 

 mals characteristic of the one into those of the other 

 series ; but in the corals, the encrinites, the trilobites, 

 and even in the shells, this is often difficult, al- 

 though there is on the whole a considerable dif- 

 ference in the general appearance of a group of the 

 fossil remains of Invertebrata taken from the upper 

 and lower series of strata. An example of this dif- 

 ference is seen in the annexed figure of a remark- 

 able bivalve shell (16, 17), not uncommon in some of 

 the rocks of the period we are now considering, but 

 altogether confined to that period. The peculiar form 

 and magnitude of the hinge teeth (fig. 17), and the 

 beauty of the shell, render it worthy of notice. 



But, although the differences of this kind are not 



