August 1907 The Irish Naturalist. 225 



VITRINA ELONGATA IN IRELAND : 

 An Addition to the Fauna of the British Isles. 



by j. w. taylor, f.l-s. 



[Read before the Irish Field Club Union, Cork Conference, 



nth July, 1907.] 



[Plate 26.] 



I have the pleasure of being able to bring forward a well 

 marked and universally acknowledged species of Vitrina 

 recentl} r discovered in Ireland, as an addition to the limited 

 mollusca fauna of the British Isles. As a preliminary it will 

 be of interest to say a few words bearing on some of the laws 

 governing the distribution of all organized beings, which may 

 assist us to a correct view of the presence in Ireland of this 

 particular species, which elsewhere is restricted to the alpine 

 regions of Central Europe, and separated \sy hundreds of miles 

 from the locality where it has now been found. 



We may take it as indisputable that weak, primitive or 

 ancient forms of life cannot extend their range or increase the 

 area they inhabit, at the expense or to the detriment of stronger, 

 more recently developed and more adaptable competitive 

 species, and any extension of range they do make can only be 

 in the direction of areas occupied by species less highly 

 organized and less dominant than themselves. Trtily domi- 

 nant species arise in the region where the most advanced 

 forms already exist and they only can really prosper, multiply 

 and extend their area of habitation in every direction to the 

 disadvantage and eventual expulsion of competitive but more 

 primitive species occupying the districts they may happen 

 to invade. 



A new and improved species being more adaptable and 

 stronger than its more primitive progenitors, will gradually 

 overcome them in the inevitable struggle for existence that 

 will ensue, so that the weaker predecessors will be eventually 

 driven from the evolutionary area and expelled further and 

 further from the regions they previously occupied, until com- 



A 



