THE LUSlTANlAN FAUNA. 30? 



As I have mentioned in the third chapter, there are a 

 good many species of Lusitanian origin in the British 

 Islands. However, we have only a mere remnant 

 of what we ought to have, had the climate been less 

 trying. It is probable, too, that the submergence 

 destroyed a good many plants and the insects depen- 

 dent on them. That the Lusitanian fauna is very 

 ancient in the British Islands is proved by the fact 

 of the discontinuous distribution of so many species. 

 A greater number survived in Ireland than in 

 England. 



Altogether and this was strongly urged by 

 Edward Forbes the Lusitanian element is the 

 oldest of the components of our fauna, and it must 

 have poured into the British Islands for many geo- 

 logical periods almost without cessation. The same 

 author, in his classic essay, refers especially to the 

 Lusitanian flora, two prominent members of which 

 are the British plants, Arbutus unedo (Fig. 20, p. 305) 

 and EupJiorbia hiberna (Fig. 21, p. 306). The former 

 has a wide range in the Mediterranean region, and 

 occurs in the British Islands only in the south-west 

 of Ireland. The Spurge, on the other hand, is also 

 found in the south-west of England, besides Ireland 

 and Southern Europe, 



