eg [Proc. B.N.F.C., 



northern one in Ireland. It has frequently been urged that this 

 Slug must have been accidentally transported to Ireland by marine 

 currents, but considering that all Slugs and their eggs are readily 

 killed by immersion in sea-water, this theory need not be seriously 

 entertained. 



A very interesting case of distribution is that of the Beetle 

 known by the name of Rhopalomcsites tardyi. It occurs in the 

 Mediterranean region and in Madeira in the south, while in 

 Northern Europe it re-appears in the British Islands. Curiously 

 enough, whereas this Beetle is decidely rare in the west of 

 England and Scotland, it is with us so common as to be classed 

 among the Irish injurious Insects. We may suppose that this 

 southern Beetle is an ancient survival which has just managed to 

 maintain its hold in a few British districts where the climatic 

 conditions are favourable, whereas in Ireland it is again actively 

 spreading, and has thus regained its former range all over the 

 country. 



Prof. Carpenter noticed that the House-Spider found in 

 Dublin and the south of Ireland differed from the ordinary 

 House-Spider, Tegenaria domeslica. He subsequently showed 

 that this large Spider is very closely related to a Pyrenean and 

 Spanish form, but that it differed sufficiently from the latter to 

 deserve a special name. It is now known as the Irish House- 

 Spider, Tegenaria hibernica. 



I might quote a good many similar instances of animals 

 which have invaded Ireland from the south. But other groups of 

 species have also originated in the south, nevertheless they do not 

 seem to have entered Ireland from that direction. Let us take, 

 for example, the handsome Snail known as Arianta arbustorum. 

 It occurs in Southern Europe, and has evidently arisen in Central 

 Europe or extended its range from that centre. As you will 

 notice from the map showing its distribution, it occurs only in 

 the north of Ireland in curious patches, having apparently 

 invaded the country from the north. Another Snail called Helix 



