DTTBUN NlTim\L 1II8T0BY SOCDBTr. 147 



which has now boon laid aside, and tho Linncan namo G1 jeimerif sobstitntcd on 

 tho ground of priority. It is recorded as haring been found in varions localities 

 and at diiTerent depths on the English coasts, and is of great beauty in the seas 

 surrounding the Channel Isles, and it constitutes both genus and species. As a 

 fossil it is found generally diffused in the tertiary formations, preserving its 

 oolour 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 surpassed. 

 In that work he points out that Pectunculus had been found on three sides of our 

 island, but that it had not been discovered in the west when his work was pub- 

 lished in 1843. I have a distinct recollection of having seen in mv first visit to 

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

 a very bad dredge which Mr. M'Calla 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 in situ hereafter. When I made 

 a more accurate examination on my visit in 1844, I found that at the entrance* 

 or nearly so, of Bcrterbie 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 ex- 

 amine the contents of the dredge after drawing it over this bank, you will find 

 they consist of obsolete valves of Pecten maximus, Lutraria elliptica, Cardium 

 Norvegieura, and Pectunculus glycimeris. Of the occurrence of the three first- 

 named shells I felt but little interest at that time, as I was tolerably conver- 

 sant 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 mv mind — from whence did 

 this largo mass of shells proceed — from what source did that supply flow ? After 

 much reflection, I arrived at the conclusion that situations 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 

 birth-places of the various animals, and, having remained there for their ap- 



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

 ay, where, meeting with the incoming tide, they were prevented from proceed- 

 ing further, and thus this accumulation had occurred. Impressed with this con- 

 viction (which I shall presently show was very fallacious), i devoted a consider- 

 able time to the examination of those banks, which were generally covered by ton 

 or twelve fathoms of water, but without any success. I suggested to the boat- 

 men 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 casina. Encouraged, I remained on the bank for a length of 

 time, tacking backward and forward, but without any further success. Although 

 this was very discouraging, still I felt gratified that I had found Pectunculus in 

 situ, thereby filling up tho points wanting in Mr. Thompson's •' Fauna." and com- 

 pleting its circle round our island ; but, on the cgntrarv, I felt somewhat morti- 

 fied 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 philosophtcallv, I did as others do in similar cases, 

 I cushioned the subject, and never reverted to it until this evening, when 1 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 obiect. Stimulated in no slight degree b^ again seeking for 

 Pectunculus, this 1 aid, but without any success; neither did 1 obtain any spe- 



