52 



Other instances might be cited, in support of the im- 

 mediate principle for which we are now contending, 

 namely, that many areas have (from local circumstances) 

 a natural superiority over others for the increase of the 

 animal tribes, even apart from the direct action of heat 

 and cold : but space will only permit me to glance at a 

 very few of them. We may detect evidences of this fact, 

 in Ireland; which, in spite of the narrowness of the 

 straits which separate it from our own country, and of 

 its independent commerce with all parts of the civilized 

 world, has an insect fauna curiously limited. From 

 what cause this may arise, whether from some obscure 

 physical influences peculiar to the soil, or (as Professor 

 E. Forbes has suggested) from the sudden impediment 

 which the establishment of St. George's Channel pre- 

 sented to the westward progress of the various species 

 from the Germanic plains, it is difficult to speculate : 

 yet the fact of its poverty remains, and we must explain 

 it as best we are able. There can be no question, that, 

 from more frequent communication with England, its 

 entomological fauna has of late years been considerably 

 increased; and it is equally easy to detect, through an 

 examination of its less inhabited provinces, that at a 

 period geologically recent its insect population must 

 have been singularly scanty. I know of few regions 

 (not even excepting the uplands of Madeira) which are 

 more deficient in insect life than the mountains of 

 Kerry. Although abounding, throughout extensive di- 

 stricts, with wood and water, and presenting every appa- 



