32 PROCEEDINGS OF SOCIETIES. 



specific name of "pilosus," but which has now been laid aside, and the Linnean 

 name, glycymeris, substituted on the ground of priority. It is recorded as having 

 been found in various localities and at different depths on the English coasts, and 

 is of great beauty in the seas surrounding the Channel Isles, where it constitutes 

 both genus and species. As a fossil, it is found generally diffused in the tertiary 

 formations, preserving its colour, markings, and villous coat in a surprising manner. 

 I will now proceed to what more immediately concerns the subject before us. Any 

 gentleman who has the good fortune to possess a copy of Mr. Thompson's " Fauna 

 of Ireland," a work which I cannot permit to pass without observing, that, although 

 small in compass, it exhibits a depth of patient research seldom equalled, never sur- 

 passed, will see that he mentions that Pectunculus has been found on three sides 

 of our island, but that it had not been discovered on the west when his work was 

 published in 1 843. I have a distinct recollection of having seen in my first visit to 

 Roundstone, some years before 1844:, obsolete valves of Pectunculi brought up by a 

 very bad dredge, which Mr. M'Alla had then in his possession ; and subsequently 

 having mentioned the circumstance to Mr. Thompson, he was unwilling, on such 

 evidence, to admit it as having been found in the west, although he candidly con- 

 fessed it was more than likely it would be found there hereafter. When I made 

 a more accurate examination in my visit of 1844, I found that at the entrance, or 

 nearly so, of Berterbie Bay a large bank of obsolete shells had accumulated in the 

 middle of the channel, and running parallel to the shore on each side ; it is so formed, 

 that by keeping close to the shore when sailing up the bay, and doing the same on 

 returning on the opposite side, you will not find a trace of this large bank ; but by 

 crossing the bay you will at once come on it. When you examine the contents of 

 the dredge after drawing it over this bank, you will find they consist of obsolete 

 valves of Pecten maximus, Lutraria elliptica, Cardiumnorvcgicum, and Pectunculus 

 glycymeris. 



"in the occurrence of the three first-named shells I felt but little interest 

 at that time, as I was tolerably conversant with their history; but as to the 

 Pectunculus I certainly was very anxious to discover its whereabouts, as I would 

 then be able to fill up the point indicated as wanting in Mr. Thompson's Fauna, as 

 well as to satisfy myself as to its habits. But the question at once presented itself 

 to my mind from whence did this large mass of shells proceed from what source 

 did that supply flow? After much reflection I arrived at the conclusion, that situa- 

 tions suitable to the various molluscs within the bay, more particularly the banks of 

 yellow sand from which the bay derives its name, and which are very numerous, 

 must be the birthplaces of the various animals ; and having remained there for their 

 appointed time their empty shells were carried by the drift to the entrance of the 

 bay, where, meeting with the incoming tide, they were prevented from proceeding 

 further, and thus this accumulation had occurred. Impressed with this conviction 

 (which I shall presently show was very fallacious) I devoted a considerable time to 

 the examination of those banks, which were generally covered by ten or twelve 

 fathoms of water, but without any success. I suggested to the boatmen that we 

 should proceed to the bottom of the bay ; and, having tried several banks there, 

 we were fortunate in finding a single specimen of Pectunculus, and one also of 

 Venus cassina. Encouraged, I remained on the bank for a length of time, sailing 

 backwards and forwards, but without any further success. Although this was very 

 discouraging, still I felt gratified that I had found Pectunculus in situ, thereby 

 filling up the points wanting in Mr. Thompson's Fauna, and completing its circle 

 round our island ; but, on the contrary, I felt somewhat mortified on finding that my 

 well-digested theory was not borne out by fact, as the supply and maintenance of 

 the accumulation never could have been brought from that quarter ; so, very philo- 

 sophically (and as others do in similar cases), I cushioned the subject, and never 

 reverted to it until this evening, when I trust to be able to give a satisfactory solution 

 of the problem. I was enabled, last summer, to revisit the scenes of my former 

 labours, and, of course, Berterbie Bay was the first object stimulated in no slight 

 degree by again seeking for Pectunculus ; this I did, but without any success, neither 

 did I obtain any specimens of the rarer shells, which I formerly got ; so that I con- 

 fess I was somewhat disappointed ; I, therefore, willingly agreed with our steersman 

 to try new ground, and, accordingly, proceeded to the ground called emphatically by 



