Geological Society of London, 375 



the Continent by means of the Mammalia." By W. Boyd Dawkius, 

 Esq., M.A., F.E.S., F.aS. 



The Pleistocene deposits may be divided into three gi'oups : — 1st, 

 that in which the Pleistocene immigrants lived, with some of the 

 southern and Pliocene animals in Britain, France, and Germany, and 

 in which no arctic mammalia had arrived ; 2nd, that in which the 

 characteristic Pliocene Cervidae had disappeared, and the Eleplias 

 meridionalis and BJiinoceros etruscus had been driven south ; 3rd, 

 that in which the true arctic mammalia were the chief inhabitants. 



This third, or late Pleistocene division, must be far older than any 

 Prehistoric deposits, as the latter often rest on the former, and are 

 composed of different materials ; but the difference offered by the 

 fauna is the most striking. In the Pleistocene river-deposits twenty- 

 eight species have been found, the remains of man being associated 

 with the Lion, Hippopotamus, Mammoth, Wolf, and Eeindeer. On 

 examining the fauna from the ossiferous caves, we find the same 

 group of animals, with the exception of the Musk-sheep ; and it is 

 therefore evident that the cave-fauna is identical with that of the 

 river strata, and must be referred to the same period. Some few 

 animals, however, which would naturally haunt caves, are peculiar 

 to them, as the Cave-bear, Wild Cat, Leopard, etc. 



The magnitude of the break in time between the Prehistoric and 

 late Pleistocene period may be gathered also from the disappearance 

 in the interval of no less than nineteen species. 



The middle division of the Pleistocene mammalia, or that from 

 which the Pliocene Cervidas had disappeared, and been replaced by 

 invading temperate forms, is represented in Great Britain by the 

 deposits of the Lower Brick-earths of the Thames valley, and the 

 older deposits in Kent's Hole and Oreston. The discovery, by the 

 Eev. 0. Fisher, of a flint-flake in the undisturbed Lower Brick-earth 

 at Crayford,^ proves that man must have been living at this time. 

 The mammalia from these deposits are linked to the Pliocene by 

 the Bh. megarliinus, and to the late Pleistocene by the Ovihos mos- 

 chatus. The presence of Machcsrodus latidens in Kent's Hole, and 

 of the Bh. megarliinus in the cave at Oreston, tends to the conclu- 

 sion that some of the caves in the south of England contain a fauna 

 that was living before the late Pleistocene age. The whole assem- 

 blage of middle Pleistocene animals evinces a less severe climate 

 than in the late Pleistocene time. 



The fossil bones from the Forest-bed of Norfolk and Suffolk show 

 that in the early Pleistocene mammalia there was a great mixture 

 of Pleistocene and Pliocene species. It is probable also that the 

 period was one of long duration ; for in it we find two animals which 

 are unknown on the Continent, implying that the lapse of time was 

 sufficiently great to allow of the evolution of forms of anijnal life 

 hitherto unknown, and which disappeared before the middle and late 

 Pleistocene stages. 



The author criticized M. Lartet's classification of the late Pleis- 

 tocene or Quaternary period by means of the Cave-bear, Mammoth, 

 Eeindeer, and Aurochs, and urged that, since the remains of all 

 1 See Geol. Mag., June, p. 268. 



