Receiit Geological Discoveries. 189 



of which we. desire to introduce those of our readers wlio may 

 not yet have learued them fi'om other souraes. 



First, the later Tertiarles have yielded some new facts, tendiug 

 to settle the perplexed questions as to the succession of cl'-matal 

 changes and vicissitudes of animal life in those latei' geological 

 periods which imme.liatel)' preceded the advent of man; and to 

 which our Canadian boidder clays and sands, with their marine 

 shells, fishes, and elephantine remains, belong. 



In the three later tertiary (Pliocene) deposits in England, 

 known in ascending order as the Coralline, Eed, and Norwich 

 Crag, the marine shells show a constantly increasing percentage 

 of recent and at the same time of northern forms ; and this has 

 just been brought forward in a precise form by Mr. Wood in the 

 publications of the Palaentological Society. The assodated re- 

 mains of land animals, however, do not appear to correspond with 

 the gradual refrigeration indicated by the shells. This difficulty, 

 long of a very perplexing character, is now beginning to be re- 

 moved by the progress of discovery. In the first place, the sea of 

 the Arctic shells has probably been open tov/ard the north, while 

 the land lay toward the south. In the next place, it has been 

 found that the mammals of the earlier of these periods difler 

 from those of the later. The Mastodon of the Crag is not the 

 M. Angustidens of the Miocene or middle tertiary, but a distinct 

 species. This Crag . Mastodon is older than two species of 

 elephant, a rhinoceros, a hippopotamus, and a monkey, found in 

 Pliocene deposits in the Valley of the Thames ; and these last 

 are still older than certain ochreous gravels in the same neigh- 

 bourhood, which contain remains of a third elephant, a second 

 rhinoceros, the reindeer, (fee. 



Here, then, we have three distinct sets of Pliocene mammals, 

 and the last only consists of animals properly arctic or sub-arctic. 

 The elephant and rhinoceros (^. Prm^'^'eftms and ^. Tichorinus) 

 are those found in Siberia, and knov/n to have been covered with 

 hair, and they are associated with bones of the reindeer and 

 musk-ox. The discovery of this last animal is of great interest. 

 It is now confined to Arctic America, but in the newer Pliocene 

 period it lived in Germany and in England, along 'with the rein- 

 deer now its arctic associate, and with the hairy elephant and rhi- 

 noceros now extinct. Prof. Owen truly remarks, that just as 

 naturalists-could hardly credit the possibility of an elephant hav- 

 ing lived in Siberia, until they found that it had been protected 



