in the neighbourhood of Belfast. 4-35 



North-western Donegal, a distance of seventy or eighty miles, 

 as such rocks occur there in situ, but they bear a much closer 

 resemblance to the pebbles of Scottish origin wljich strew the 

 shores at the mouth of the bay; and thus they point back to 

 that remote condition of things, when the whole trap district 

 was still rising above the level of the sea, but when the elevated 

 country at the base of the mountains, from Belfast to Car- 

 rickfergus, was yet under water, and the waves were beating 

 against the base of the basaltic precipices. 

 The following is a list of the shells : — 



Rostellaria pes-pelecani Nucula oblonga (Brown). 



Fusus antiquus ... margaritacea, fragments 



var. containing several, Cardium echinatum 



rolled ... edule 



... corneus ... nodosum 



... lamellosus, or peruvianus, Tellina solidula 



one, and fragments Mactra elliptica 



BamfRus, rare ... truncata 



Murex erinaceus Cyprina Islandica 



Buccinum undalum Venus ovata 



elongated, var. ... gallina 



B. fusiforme, Humph., ... decussata 



Zoo]. Journ. ... aurea 



Nassa reticulata Astarte Damnonia 



Purpura lapillus ... multicostata, abundant 



Turritella terebra ... Scotica 



Littorina littoreus ... Gairensis, abundant 



retusa, one specimen ... compressa (Smith), same as 



Trochus tumidus, one fragment Clyde shell 



Natica clausa, rare ... ... another, distinct 



Emarginula fissura, one specimen Amphidesma compressum 



Ostrea edulis Saxicava rugosa 



Pecten maximus, fragments Serpula vermicularis 



Mytilus edulis Balanus, many pieces with a few 



Pectunculus pilosus valves. 



Area lactea 



A comparison of this list with the shells of the Clyde de- 

 posits, described by Mr. Smith of Jordan Hill, and with those 

 of other parts of Ireland, suggests many interesting reflections. 

 One most abundant species, Astarte Gairensis, abounds also in 

 the Clyde deposits, and is fou!ui near Dublin in several places, 

 but does not inhabit Belfast Bay at present, and is rare in the 

 Clyde. The occurrence of this species, of the Nucula oblonga, 

 and some others, seems to connect, as of one age, the deposits 

 of the west of England, the Isle of Man, the eastern and north- 

 ern parts of Ireland, and the basin of the Clyde. I must, 

 however, refer to Mr. Oldham's paper already mentioned for 

 some very interesting remarks on this subject. See also Mr. 

 Lyeli's observations on the connexion of the Canadian, Swe- 



2G2 



