ZOOLOGICAL AND BOTANICAL ASSOCIATION. 205 



observed in foreign than in native examples of the present day. This 

 mollusc is not now an inhabitant of the harbour ; nor indeed do I know 

 any habitat nearer than Portpatrick, in "Wigtonshire, a harbour pre- 

 senting geological features corresponding to some of those of Belfast 

 Bay. In both these places there is an identically similar formation of 

 grauwacke, containing the same minerals. I do not know whether this 

 would have any effect in favouring the presence of the Teredines. Mr. 

 Hyndman has also met with the species in wood dug up in making 

 sewers in Belfast. 



Pholm dactylus (Linneus). 

 A single valve of this species was found by myself in the sand 

 which had been raised near Holywood for the construction of the rail- 

 way. It still exists in some numbers at Cultra, about a mile farther 

 down the bay, where I have met with it boring into the sandstones of 

 the curious series occurring there, about which there has been so great 

 a controversy as to whether it should be referred to the Permian or 

 Carboniferous system. 



Pholm parva {Pennant). 

 This species has not been met with in the deposits by myself or by 

 any one else of whom I inquired, but I am informed that Dr. Drummond 

 found it in the submerged peat in the dead state, which is its only ap- 

 pearance in the bay. 



Pholas crispata (Linneus). 



Several extremely fine examples of this species were found in the 

 silt by myself, one measuring four and a half inches in length, and two 

 and a half in breadth, by much exceeding the largest recent specimen 

 measured by Messrs. Forbes and Hanley. It is not now common in the 

 bay, and it attains but a comparatively diminutive size. 



Pholm Candida (Linneus). 

 A tolerable number of single valves of this species occurred in the 

 clay with a few perfect specimens, all of which were so large as to sug- 

 gest the thought that they " died of old age." The best specimen mea- 

 sured three inches in length, and one and a quarter in breadth. It is 

 at the present day abundant in the harbour, burrowing in the sand- 

 stones and variegated marls on both sides of the bay. 



