8 The Irish Naturalist. January, 1923 



Thracia pubescens near Dublin. 



While exploring the South Bull in Dublin Bay recently I picked up 

 a single valve of Thracia pubescens. Mr. A. R. Nichols and Dr. R. LI. 

 Praeger were kind enough to examine it, and apparently it is a fossil 

 shell, but rarely found in Ireland. Birterbuy Bay appears to be the only 

 spot on the Irish coa^t where a live specimen had been found. 



Dublin. John A. S. Palmer. 



Mr. Palmer's finding of Thracia pubescens in Dublin Bay is very 

 interesting. The Irish records are very few (see Nichols, " Marine 

 Mollusca of Ireland," Proc. R. I. Acad., 1900) and may be grouped as 

 Belfast Lough, Dublin Bay, Cork Harbour, and Birterbuy Bay in 

 Connemara. Of these, the only station where living specimens were certainly 

 obtained is Birterbuy Bay (a fine specimen in Dublin Museum). The 

 Belfast specimens were undoubtedly fossil : the Turbot Bank is a famous 

 deposit of fossil shells : Grainger obtained it in the Belfast Estuarine 

 Clays, and myself in the similar deposits in Larne Lough, The Cork 

 records are so far as I know unsupported by specimens, and it is not stated 

 whether the speciinens were recent. But as the species lives in Connemara 

 it may well do so at Cork. The only Dublin record is very vague ; — " Near 

 Dublin, Mr. Warren" (Thompson, vol. iv.) The British distribution is 

 very restricted — the south-western coast only : but in his " Additions 

 to British Conchology " (Journ. of Conch, viii and xiv), Mr. Marshall 

 unexpectedly adds a few Scottish records which seem more or less 

 doubtful. The foreign range is exclusively southern, extending from 

 Britain along the Mediterranean and south to the Canaries. 



The species is then clearly one of the southern forms which flourished 

 as far north as the Ulster coast during the Neolithic climatic optimum 

 (to which the Belfast and Larne Clays belong), but which has since 

 retreated to the slightly warmer waters of the west and south coasts. 

 Mr. Palmer's valve is I think certainly fossil : no trace of the ligament 

 remains, and the shell is blackened and opaque — not nearly so fresh 

 in appearance, indeed, as the Larne fossil. Its past and present range 

 is paralleled by that of Gastrana fragilis, found fossil in Neolithic clays 

 at Downpatrick and Clontarf, and still living on the west and south coasts 

 of Ireland, south-western England and thence on to the far end of the 

 Mediterranean. 



The Shetland record (Forbes, Brit. Assoc. 1850) and the single valve 

 from Drontheim (Jeffreys, vol. ii., p, 368), as well as the single valve from 

 Campbelltown and other Scottish records, I would be inclined to refer 

 to fossil relics of the Neolithic fa^inia. There is a Greenland record which 

 seems more than doubtful. 



R. Lloyd Praeger. 

 Dublin. 



