214 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 24, 



sea, and here and there occupy in the winter the pastures that 

 afforded food to Preglacial or Pliocene mammals in the summer. 

 And in this way the remains of animals indisputably Preglacial or 

 Pliocene may be mingled with those indisputably Postglacial or 

 Quaternary in the deposits of the same stream. Thus the presence 

 of the R. megarhinus and of the hardier members of the Preglacial 

 fauna, the Eed Deer, Horse, Urus, and possibly C. megaceros, in 

 association with the Mammoth, Tichorhine Khinoceros, and Musk- 

 sheep may be accounted for. On these grounds the deposits in 

 question have been separated from the ordinary Postglacial series. 

 They probably form the first terms of the Postglacial series, and 

 point back to a time when the Postglacial invaders had not taken 

 fuU possession of the district. And inasmuch as no North- Asiatic 

 mammal has yet been found at Clacton, while several have been 

 found in the Lower Brickearths, the former is considered of higher 

 antiquity than the latter. They bridge over that vast interval be- 

 tween the Preglacial or Pliocene and the Postglacial or Quaternary 

 epochs that is sharply marked in Britain north of the Thames by the 

 deposit of the Boulder-clay, but which in the south of England and 

 in France and Italy is not clearly defined. On this hypothesis the 

 passage from the Phocene to the Postglacial series would be as 

 follows: — 1, Pliocene of France and Italy; 2, Preglacial (? Plio- 

 cene) of Forest-bed ; 3, Passage-bed of Clacton ; 4, Postglacial Pas- 

 sage-beds of the Thames valley ; 5, Postglacial series. I am nnable to 

 offer any opinion about the identity of the Forest-bed fauna with 

 that of the foreign Pliocenes. 



There is also another point bearing on the question of the relation 

 of the Pliocene to the Postglacial fauna that I have referred to this 

 place, the occurrence of the Pliocene MacJiairodus in the midst of 

 the remains of Reindeer, Cave-hysena, Mammoth, Tichorhine Ehi- 

 noceros, and other characteristic Postglacial mammals. Its presence 

 can only be accounted for on the supposition that it strayed north- 

 wards from its southern habitat, very much after the fashion of its 

 living congener the Tiger of Northern Asia. There is nothing more 

 improbable in the idea that a small body of southern carnivores 

 should have preyed upon the Eeindeer in the neighbourhood of 

 Kent's Hole than that a Tiger specifically identical with that of 

 India should at the present day find convenient food among the 

 herbivores of Siberia. It indicates, however, one important fact, 

 that while the Postglacial mammals were in full occupation of 

 Britain, the Pliocene fauna to which belongs Macliaii^odus occupied a 

 zoological province further to the south. 



13. Postglacial Climate. — We hav^e now, in conclusion, to consider 

 what was the nature of the cHmate under which the Postglacial mam- 

 mals hved. Sir Charles Lyell and the authors of the * British Pleis- 

 tocene Mammalia ' agree in the belief that it was continental in cha- 

 racter, while Britain formed a part of the Postglacial continent, or, in 

 other words, that the extreme cold of winter and the extreme sum- 

 mer-heat were more in tense than in the present condition of things. The 

 evidence of the contorted gravels, and the traces of terrestrial glacial 



