THE FAUNA OF BRITAIN. 115 



bution," which zoologists are agreed to regard as a 

 sign of antiquity. Thus Geomalacus maculosus, the 

 Kerry Slug, is in the British Islands confined to South- 

 western Ireland (see Fig. 19, p. 300), and on the Con- 

 tinent it is unknown north of North-western Spain. 

 The Millepede, Polydesmus gallicus, has a wider range 

 in Ireland, and is also known from France and the 

 Azores. Two Earthworms of the Spanish and 

 Mediterranean region, viz., Allolobophora veneta and 

 Georgii^ have been discovered in Ireland, but are 

 apparently unknown in England or France ; whilst 

 the Weevil, OtiorrJiyncJius auropunctatus, does not 

 occur north of the Auvergne Mountains in France 

 except in Ireland. A very large number of instances 

 might be mentioned of species found in South- 

 western Europe, France, the South-west of England 

 and Ireland. Enough, however, has been said to 

 show the nature of the fauna, and there is, as 

 Forbes has pointed out, a corresponding flora. 



A great number of the species belonging to the 

 South-western British element seem to have origin- 

 ated in South-western Europe, or at any rate to have 

 spread over our continent from that part. Their 

 home lay therefore probably in a warm, damp 

 climate, and it seems a reasonable inference to 

 suppose that they spread north at a time when 

 the temperature over the British Islands was much 

 higher than what it is now. Any one familiar with 

 our Bristle fern, or Killarney fern, as it is called in 

 Ireland (Trichomanes radicans}, will readily admit that 



