1878.1879.] 349 



been made considered the Lough Neagh clays to be of the 

 Pliocene age, and the discovery by that gentleman of a bed of 

 shells in the Crumlin river caused considerable importance to be 

 attached to the beds, as may be learned from the concluding 

 paragraph of the paper to the Irish Geological Society, which is as 

 follows : — " In the meantime it is right to place it on record, 

 seeing that this place is the only locality in the British isles yield- 

 ing lacustrine fauna of Pliocene date." Mr. Swanston's examina- 

 tions having led him to form a different opinion, not only regard- 

 ing the fossils, which had been referred to the genus Unio, a fresh 

 water shell, but also respecting the age of the containing beds, he 

 proceeded to point out the evidence on which that opinion was 

 founded. The shells having all the appearance of a marine, and 

 not a fresh water mussel, a good series of them were forwarded to 

 Dr. J. G. Jeffreys, F.R.S., for identification, who, with his usual 

 kindness, states— " . . . . After examining them I can 

 come to no other conclusion but that the shells belong to our 

 common mussel, Mytihis edulis, which occurs in all our newer 

 tertiary formations. The colour, structure, and composition 

 agree." 



A quantity of the material of which the beds is composed 

 was submitted to Mr. Joseph Wright, F.G.S., of Belfast, for micro- 

 scopic examination. Mr. Wright states that the only microzoa 

 which he was able to detect in it were a few Foraminifera, refer- 

 able to four species, all of which are found living on our coasts, 

 and are also of frequent occurrence in the Pleistocene boulder 

 clay. An examination of the stratigraphical position of the fossil- 

 bearing beds, proves that they repose upon the true boulder clay, 

 which is full of ice-marked stones. As the Mytilus is a sea shell, 

 and Foraminifera essentially marine organisms, it is clear that the 

 beds are not of lacustrine origin. The fact that they repose upon 

 boulder clay proves that they must be either glacial or inter- 

 glacial deposits, not Pliocene. The author of the paper referred 



