140 



The Irish Naturalist. 



December, 



With regard to the shelly deposits of the ice sheet which 

 invaded the eastern margin of the central plain, and which 

 are usually quoted in support of the submergence theory 

 we are in possession of a considerable amount of accurate 

 information, as this area has been under observation for 

 many years and includes the famous high level shelly drifts 

 of Kilmashogue at 1,200 feet above sea-level, the equivalent 

 in Ireland of the Moel Tryfaen deposits in North Wales 

 on the other side of the Irish Sea. 



If we examine the shelly drifts of Leinster we find 

 that shell-fragments have been collected in situ, and 

 undoubtedly m situ, in various localities east of a line drawn 

 from Clogher Head in Louth, to Castlecomer in Kilkenny, 

 and that in sheltered and favoured places it is possible 

 with diligent and persistent collecting over long periods 

 to find many specimens in a sufficiently good state of 

 preservation for purposes of identification. The most 

 noted of the collections made in this province are those 

 made by Maxwell Close at Ballyedmonduff and Kilmas- 

 hogue, by R. LI. Praeger and Prof. Sollas at Kill-of-the- 

 Grange near Kingstown (now Dunleary) , and by the present 

 writer at Larch Hill in the Dublin Mountains and at the 

 Ford of Fine in the Naul Hills, the latter investigation 

 being made with the assistance of a research grant from 

 the Royal Society of London. About 45 species of mollusca 

 have been identified in these collections, and include the 

 usual percentage of arctic and northern forms, but it is 

 essential to bear in mind that the number of shell frag- 

 ments which have to be collected before even a short list 

 of species becomes possible is very great indeed ; that as a 

 typical instance, over four thousand shell fragments had 

 to be gathered at Larch Hill in order to make possible a 

 list of 42 species, and in other localities a similar proportion 

 obtains. 



What is the palaeontological value to be assigned to these 

 many thousands of shell fragments found on the eastern edge 

 of the central plain ? Are they sufficient evidence of the 

 postglacial submergence which Prof. Gregory proposes for 

 the formation of the Fskers ? The palaeontological value 

 of these shell fragments is as follows : they are valuable 

 evidence of the climate which existed in the Irish Sea area 



