March. 191. 



KXOWLI-.Or,]- 



suggested, indeed, bv 

 several writers that the 

 Lusitanian element in the 

 Irish flora is due to or- 

 dinary accidental causes, 

 such as winds and ocean 

 currents. 



When we surve\- the 

 fauna and flora of the 

 British islands as a whole, 

 we find that there are 

 quite a number of Lusi- 

 tanian plants and animals 

 that are not confined to 

 Ireland, but inhabit also 

 the south of England. A 

 few species ha\-e even 

 invaded the west of Scot- 

 land, although they seem 

 to occur, as a rule, more 

 abundantlv in Ireland 

 than in Great Britain. 

 Among such plants may 

 be mentioned the Irish 

 Spurge (Eiiphorhia 

 hiberna, see Figure 96 1 

 which grows very abund- 

 antly in the south and 



west of Ireland, while it is also met with in a few 

 isolated spots in Devonshire. As an instance of 

 a Lusitanian animal belonging to this group, the 

 beetle Rliopiiloiiiesifes tardyi (see Figure 91) may be 

 cited. This weevil is so common in Ireland that it 



St. Dabeoc'; 



FlGURF. 9^1. 

 The Irish Spurge tEiipliorbiti liihcnui* 



FiGlui-: 9.T. 

 Heath UJnl>cocia poUfolui\. Romidstone. 



is classed among the most injurious Irish timber 

 insects. In Great Britain it is only known as a 

 rare insect in the south-west of England and 

 Scotland. 



Hence, we now know that the Lusitanian ele- 

 ment in our fauna and 

 flora, though much more 

 conspicuous in Ireland, is 

 not peculiar to that 

 country. This fact greatly 

 weakens the arguments 

 in favour of accidental 

 dispersal. To anyone, 

 moreover, who has made 

 a careful study of the 

 mode of occurrence of 

 these plants and animals 

 in the British Islands, it 

 must be apparent that 

 they are old-established 

 species, most of which 

 are being crowded out or 

 supplanted by newer 

 rivals better fitted to w ith- 

 stand the existing climatic 

 conditions. They all have 

 a discontinuous range, 

 which, as Wallace has 

 taught us, is a sure sign of 

 antiquity. Most of them 

 occur here and there in 

 isolated patches or locali- 

 ties surrounded by species 

 of quite a dift'erent type. 



