50 Proceedings of the Royal Irish Academy. 



Tapes decussatus, L. A soutliem shell, wLicli first a^jpeared, like- 

 tlie last, in the "Waterworks boulder- clay. Attained immense 

 profusion in the estuarine clay period, but has noTv become 

 completely extinct in the district, having its limit in Lough. 

 S^villy on the one side, and Carlingford Lough on the other. 

 Beyond these limits it is a common species round the Irish shores. 



Lucinopsis undata, Penn. Attained an abundant and luxuriant 

 development in the estuarine clay period : now almost extinct 

 in the district, but found at Portrush and ]y[agilligan. Lives 

 in Lough Swilly and westward, and on the eastemside at 

 Dublin. 



Gastrana fragilis, L. A southern shell, which appears in the estua- 

 rine clays of Strangford Lough. In a living state its nearest 

 station is Lough Swilly. Elsewhere in Ireland, its present 

 stations are in the south and west. 



Scrohiculariapiperata, Bell. Appears in the "Waterworks boulder-clay. 

 In the lower, or littoral, estuarine clay it is almost invariably 

 present in immense profusion, along the whole north-eastern 

 coast. !N^ow quite extinct in the same area, having its nearest 

 stations just outside these limits, in Lough Swilly and in 

 Carlingford Lough. Common all round the rest of the Irish 

 coasts. 



Rissoa alhella, Loven. Occurs, often in enormous numbers, in almost 

 every bed of estuarine clay in the loughs of Poyle, Lame, 

 Belfast, Strangford, and Carlingford, as well as in the Portrush 

 raised beach. Xow completely extinct, and in Ireland only found 

 at Bantry Bay in the extreme south-west. 



Equally instructive is the evidence afforded by certain raised 

 beaches of the former extension northwards and eastwards of species 

 which are characteristic of the west-coast fauna. 



Vemis verrucosa, L. A southern shell, recorded from the Portrush 

 raised beach, and from prehistoric shell-mounds at Piosapenna in 

 North Donegal. 1 It is an abundant species in the south-west, 

 now finding its limit on the south coast at Youghal, and on the 

 west coast in Co. Sligo. 



Venerupis irus, L. Another characteristic west-coast species of southern 

 type, not now known north of Bundoran, but occurring in the 

 Portrush raised beach. 



1 ^V. H. Patterson, ia Irish Xatiiralist, iii., p. 50 (1894). 



