572 



SCIENCE. 



[N. S. Vol. XI. No. 276. 



the volcanic disturbances in Central Europe 

 and the hot spring formation of Thuringia 

 (Taubach, Weimar) ; at this time all the old 

 continental connections characteristic oj the Ter- 

 tiary and serving as land bridges for free Hol- 

 arctic Oriental and Ethiopian migration began 

 to break up in the folloiving manner. Dur- 

 ing the early mid-Pleistocene or Elephas 

 antiquus stage (Pohlig) the English cbannel 

 broke through the long pre-existing land- 

 bridge between Eugland and France ; Great 

 Britain was faunallj^ isolated ; similarly the 

 Irish Channel was depressed and Ireland 

 (Scharff, 1894) lost its land connection with 

 Wales in the early Pleistocene and with 

 Scotland in the newer Pleistocene. In the 

 Mediterranean region, also, at the close of 

 the first interglacial period (Pohlig), the 

 land-bridge across Gibraltar, also that be- 

 tween Italy, Sicilj' and Africa was broken ; 

 Malta was isolated as an island and the 

 great Elephas antiquus dwindled into the 

 small insular type E. melitensis. To the 

 eastward the Mediterranean Sea extended 

 over the iEgean plateau, which had previ- 

 ously been terra firma, and the new JEgean 

 Sea cut o& the land connection between 

 Greece and Asia Minor. 



I. Preglacial. Elephas meridionalis Period. 

 The typical preglacial deposits are the 

 Forest Beds of Norfolk, England. The 

 weight of opinion and of fact is all upon 

 the side of considering these beds as Pleis- 

 tocene. From the lists given by Dawkins, 

 Schlosser and other writers, the Preglacial 

 period is found to contain : 



12 Pliocene species. 



32 Pleistocene species and races, now extinct. 

 17 Living species, of which 7 are Insectiyora and 

 Cheiroptera. 



The most remarkable feature of this 

 fauna is the mixture of African and North 

 Asiatic forms. The great Elephas meridio- 

 nalis a precursor of the Mammoth, is the 

 most characteristic type. The first traces 



of man in the paleolithic flints of the Che- 

 leen type occur upon this level. 



The climate, judging by the flora and 

 Conchylien fauna, was somewhat cooler 

 than that of the upper Pliocene. The first 

 arctic flora in England is in a layer which 

 separates the Forest Bed from the glacial 

 Boulder Clays. To this period, according 

 to most authorities, the Pithecanthropos erec- 

 tiis of Dubois belongs. Others, including the 

 late Professor Marsh, consider this link be- 

 tween man and apes, of Pliocene age. 



II. Glacial and Interglacial, or Mid- Pleistocene. 



1. Lower Mid- Pleistocene. Loiver Stage. — 

 In climate the early part of this period, 

 immediately during and succeeding the ice 

 period, was very extreme. None of the first 

 ice pei'iod fauna is known unless we except 

 Elephas (^primigeniui') trogontherii or E. in- 

 termedins and the red deer, Cervuselephas, 

 the latter being doubtfully recorded from 

 the Boulder Clay of England. Here, in the 

 Eixdorf beds, we find the first arctic and sub- 

 arctic tj'pes of animals in central Europe. 



MiddleStage. — This stage (Mosbach Sands, 

 Essex) marks the recurrence of a more tem- 

 perate climate, first observed by Lyell and 

 Evans in England and abundantlj' known 

 in Germany and France. Two only of the 

 characteristic Pliocene species recur, the 

 hippopotamus and straight- tusked elephant. 

 These alone have been universally cited as 

 evidence of a south temperate or even of a 

 tropical climate, but the more numerous 

 hardy types which are found in this stage 

 constitute still stronger proofs of a north 

 temperate climate. 



Geologically the deposits are of fluviatile 

 origin consisting of river sands and gravels 

 containing Hipipopotamus, Rhinoceros merchii 

 and Mammoth. The great beaver, Trogon- 

 therium euvieri makes its last appearance 

 here. Geographically the southern conti- 

 nental depression has not begun and the 

 Lower Pleistocene land bridges persisted. 



