38 OSBORN. 



mals as water. The Sahara desert although elevated during the 

 Tertiary was another faunal barrier and northern Africa was 

 zoologically a part of Europe. In the far northeast the Behring 

 Straits were formed and after a complete community of arctic, 

 boreal and north temperate faunas had been established, the 

 Nearctic region or North America was completely isolated from 

 the Palaearctic or Europe and Asia. (See Fig. III.) 



StratigrapJiy . — Faunally the strata record is far less exact 

 than in the preceding Tertiary periods owing to the wide spread 

 removal of easily eroded materials. Yet definite stratigraphic 

 succession occurs in many places and upon the whole the faunal 

 succession as shown in column V of the Table, p. 36, is as fully 

 and definitely known as in any previous division of the Tertiary. 

 In the sands of St. Acheul, near Paris, ElcpJias antiqims occurs 

 at 7 metres, Hippopotanms aniphibuis at or below 5 metres, 

 ElepJias priinigenius never below 3 metres. The most exact 

 stratigraphic records are those of the caves near Schaffhausen 

 for example ; here a general succession of types is positively 

 ascertained. 



1. Preglacial, Elephas meridionalis Period 



The typical preglacial deposits are the Forest Beds of Nor- 

 folk. The weight of opinion and of fact is all upon the side of 

 considering these beds as Pleistocene. Deperet ('93, p. 538), 

 is strongly of opinion that they are transitional between Pliocene 

 and Pleistocene with prevailing affinities on the latter side. He 

 places with them as of the same age St. Prcst (Eure et Loire), 

 Diirfort (Gard) where a magnificent skeleton of EhpJias merid- 

 ionalis was obtained for the Paris Museum ; Mcdhattii, Peyrolles 

 (Auvergne, Puy-de-D6me). 



From the list given by Dawkins ('80, '94), Schlosser and 

 other writers the Preglacial period is found to contain : 



1 2 Pliocene species ; 



32 Pleistocene species and races, now extinct; 

 17 Living species, of which 7 are Insectivora and i 

 Cheiroptera. 



