BAILY ON MARINE INVERTEBRATA AT EORTMARNOCK. 251 



Captain Hutton observed, that the physical structure of the recks 

 upon which these Perns grew was an important point. Were they 

 hard, or did they disintegrate easily ? Did they absorb moisture 

 easily, and, when absorbed, did they retain it ? The answers to these 

 questions might throw light on their preferences for particular rocks. 



Mr. Harte, in reply, said that he never recollected to have seen the 

 Osmunda regalia upon limestone. There was a fringe of Carboniferous 

 rocks round the Bay of Donegal ; and near, but not on, the limestone 

 the Osmunda appeared growing luxuriantly a few hundred yards from 

 the granite mountains. At the same time, circumstances might cause 

 it to grow or struggle upon a limestone soil, or upon stiff clay, which 

 it appeared to do sometimes, owing to the spores being carried over 

 from its natural habitat. People were often mistaken as to what lime- 

 stone was. The beds in the yellow sandstone system sometimes alter- 

 nated so rapidly, that what might seem to be a limestone was in reality 

 a sandstone soil. As to the physical structure of the rocks upon 

 which the Hymenophyllum Perns were found, they differed from each 

 other in this respect, that the Pern at Lough Eske grew upon a coarse- 

 grained conglomerate at the base of the yellow sandstone, and near the 

 Old Eed Sandstone, probably belonging to some passage beds which 

 occurred there, between the two. This rock was easily disintegrated, 

 and different in texture from that which this Pern grew upon at Lough 

 S willy. The latter rock was a sandstone also ; but, though chemically 

 the same, so altered in condition as to be completely fused, quite hard, 

 and weathered very slowly. The Osmunda regalis grew from six inches 

 to nearly five feet in height. 



The following paper was then read : — 



Notes on Marine Invertebrata, collected on Portmarnock Strand. 

 By W. H. Bally, P. L. S., P. G. S. 



The following remarks principally relate to a number of marine ani- 

 mals belonging to the Radiata, Articulata, and Mollusca, collected by 

 me in the month of March of last year, on the sea shore at Portmarnock 

 — an account of which may perhaps prove interesting, if only to show the 

 great variety of forms of organic life observed on one visit, and during 

 a short space of time, owing, most probably, to a peculiar condition of 

 the wind and tide. 



Having arrived at the fine stretch of sands, so appropriately called 

 the Velvet Strand, just at the proper time, which was immediately 

 after high water, I found the shore strewed with living creatures left 

 by the retiring tide, presenting a sight which could not fail to interest 

 a lover of natural history. Most conspicuous amongst these "waifs 

 and strays" were hundreds of a large Jelly Pish (lihizostoma), Star 

 Fishes of various kinds, and an abundance of the common Heart Ur- 

 chin (Amphidotus), with Sea Mice (Aphrodita), numerous Mollusca 



