350 THE HOLARCTIC REGION. [CHAP. 



t Fallow Deer. Cervus dama. I. 



Roe Deer. Capreolus caprea. 

 *Wild Boar. Sus scrofa. I. 



The total number in this list is only 28, out of which at least 

 four are introduced. With the exception of the recently-described 

 assogue 1 , which is intermediate between the stoat and the weasel, 

 and is peculiar to Ireland, the whole of these mammals are com- 

 mon to the Continent. As shown in an earlier portion of the 

 present chapter, during the Plistocene epoch Britain possessed a 

 fauna apparently identical with that of the Continent ; and there 

 must accordingly be some good reason for its present poverty in 

 mammalian life as compared to the latter area. The difference is 

 accounted for by Dr Wallace, through the occurrence of one or 

 more periods of subsidence, which took place during the close of, 

 or subsequent to, the Glacial epoch ; after which England again 

 became united to the Continent, when its present fauna entered, 

 the period of connection being, however, of comparatively short 

 duration, and thus permitting of the passage of only a moiety of 

 the continental forms, or those which happened at the time in 

 question to be inhabiting the districts nearest to the connecting 

 line. Only a certain number of the mammals which thus crossed 

 into Britain have ever succeeded in reaching Scotland ; and it is 

 from this country, if we accept the views of Dr Scharff, referred to 

 above, that Ireland appears to have received its still more im- 

 poverished mammalian fauna. 



It will be seen that the foregoing hypothesis attributes the 

 clean sweep supposed to have been made of the original British 

 fauna to the effects of submergence, and not to the ice-sheet. On 

 the other hand, Mr G. W. Bulman 2 , who doubts whether the sub- 

 mergence has been sufficient for this, attributes such extermination 

 as he believes to have taken place solely to the effects of an ice- 

 sheet. And he further believes that a number of the original 

 British mammals survived in the southern and south-western 

 counties of England, whence they re-populated Britain on the 

 disappearance of the ice-sheet, without there having been any 



1 See Thomas, Natural Science, Vol. vi. p. 377 (1895). 

 - Appendix, No. 12. 



