210 DUBLIN UNIVERSITY 



therefore, have been deposited before the formation of the ford twelve 

 hundred years ago. The Subtruncatse appeared exactly similar to those 

 of the present day. The species is still abundant in the sand of the 

 bay, and from its being found in company with Cardium edule, obtains 

 commonly the epithet of " Lady-cockle." 



Lutraria elliptica {Lamarck). 

 Was embedded everywhere in the sand and mud in numbers, retain- 

 ing in some degree its thin olive-coloured epidermis. One example 

 measured five inches in length, and three in breadth. Another had a 

 curious accumulation of shelly matter inside one valve, very hard, and 

 nearly half an inch in thickness. It is yet a not unfrequent species in 

 the harbour, in a fresh, but not a living state. 



Lutraria oblonga {Chemnitz). 

 A remarkably fine specimen of this now absent species occurred to 

 the late James Lemon, Esq., a graduate of your University, and a much 

 esteemed, though youthful Member of your Association. 



Tapes decussata (Linneus). 

 Appeared pretty often in the bluish sand of the deposits, generally 

 preserving its decussation of concentric sulci, and radiating striae. No 

 remains of colouring could be detected. Some examples were of a large 

 size. I suppose I should refer to the post-tertiary deposits a remark- 

 ably perfect specimen which I took from the mortar of the wall of 

 the orchard of a very ancient ecclesiastical building giving name to the 

 townland of Monkstown, which has been identified by the Kev. Dr. 

 Reeves with Killana-manach, a name current in 1643, when the ori- 

 gin of the edifices was a mystery, and there were only ruins even then 

 to give a clue. It has been dug out of the sand opposite Jordanstown 

 in the living state. 



Tapes pullastra ( Wood). 



Was met with very abundantly in the sandy mud in remarkable pre- 

 servation. Its variety Perforans did not occur, perhaps because there 

 were no stones to afford it a habitation. One specimen measured an 

 inch and three-quarters in length, and an inch and a quarter in 

 breadth, and had by no means reached the maximum size of its fellows. 

 It is extremely abundant at present along the shores of the harbour. 



