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conclusions not essentially diflferent from what I have endeavoured 



to set forth now. 



There yet remains the question as to what the life of the period 

 was like, and a very important question it is too. In these days, 

 when the mind of every thoughtful person is more or less stirred 

 by questions concerning the relations of hfe of the Present to that 

 of the Past, we peer with intense interest into the past life history 

 of every formation in the least degree likely to furnish material for 

 the more complete knowledge of the past succession of life. The 

 life of the older Carboniferous Period is represented by a consider- 

 able variety of forms of both animal and vegetable life, which may 

 be met with in abundance within a radius of even a few miles from 

 our present position. But in the long lapse of time that intervened 

 between the close of this older formation and the commencement 

 of the great series of marine deposits, represented by the Lias, the 

 whole of the varied and abundant marine fauna of the Carboniferous 

 epoch seems to have been almost entirely replaced by another and 

 totally different set of forms. No one now-a-days believes that 

 this great revolution took place all at once. Somewhere or other, not 

 far off, were the modified descendants of the older forms. Whence 

 came the forms that took their places ? Did the Carboniferous 

 animals migrate farther and farther away as changed physical 

 conditions rendered their existence impossible ? Or did their 

 descendants recede only to such a distance as suited their modes 

 of life, to return again and again, in a more and more modified 

 form each time the old Physical Geography was adapted to their 

 existence ? So far as the Penrith Sandstone itself is concerned we 

 are unable to answer these queries. To make any comparison at 

 all we must be sure that the animals whose forms we are comparing 

 lived under the same conditions. It would not do, for instance, 

 to expect to find much resemblance between the animals whose 

 remains may happen to be dredged up from the bottom of Ullswater 

 and those that we may obtain from the sea bottom off Whitehaven. 

 We must compare marine life with marine. Close above the 

 Penrith Sandstone, however, comes a deposit that looks as if it 

 had really been partly marine. What fossils we do get in it 



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