24 DUBLIN NATUKAL HISTORY SOCIETT. 



fine specimens, being larger than any I had taken from the many loca- 

 lities I had found them in. I suppose it would be in vain to account for 

 the magnitude of your specimens — that is to say, whether it is from age 

 or from some fine fattening ground they are in — because, the species 

 being generally difi'used over the bay, how is it, in the hundreds I have 

 taken, that mine are not one-third the size of yours ? In Roundstone 

 Bay I also found them abundant, but of the average size of my other 

 specimens. I find that every conchologist can boast of having some 

 species far superior to those in the best collections ; and you may rest 

 satisfied that no cabinet can show finer Pectunculm glycimeris, Akera 

 lullata, and Kellia suborhicularis, than your own. These three species I 

 now remember, and there may be others you have that may vie with 

 them." 



You perceive Mr. Clark attributes the colossal growth of the molluscs 

 to the stimulus of their being exposed without interruption to the pure 

 Atlantic wave; Mr. Barlee, to age and the peculiar quality of the ground 

 on which the animals were placed. That none of these agencies are suffi- 

 cient to account for the monstrous growth of these specimens is shown 

 by the fact, that the animal, when exposed without interruption to the 

 Atlantic wave, never, at least so far as our investigation warrants us at 

 present in saying, attain such a size ; as is plainly seen in these spe- 

 cimens from Roundstone Bay, which is completely unprotected, or, 

 in other words, exposed to the open sea in that spot whence the speci- 

 mens were procured; and the inference drawn by Mr. Barlee, as to 

 the fattening quaUty of the ground, cannot be maintained, inasmuch as 

 the composition of the soil is identical in every creek in both bays, con- 

 sisting of decayed or decomposed nullipore ; and this4>eing a very light 

 substance, is wafted by the tide towards the shore, and forms the margin 

 of all the inlets, and it is on this Akera hullata is to be found. 



I am sure both these gentlemen will agree with me, that there 

 is one essential condition, probably combined in a degree with each of 

 their suggestions, which should be present to account for this great growth, 

 and that is, perfect tranquillity, or freedom from disturbance ; and this 

 state is to be found in an eminent degree in the spot I obtained those spe- 

 cimens. You may recollect I mentioned that, on getting under the high 

 land of Innisnee, we passed from the agitated waters of the bay into water 

 as smooth as a mill-pond, although it was blowing a fearful gale overhead, 

 the wind veering from west to south-west. On carefully examining the 

 locality, I found it completely land-locked, sheltered on every side by 

 high land ; and it should be observed that the north and east winds, 

 which on the easterly side of our island produce such a rolling and 

 tumbling sea, on the west coast act in an opposite manner, stilling the 

 water, and not even producing a ruffle on the surface : so that, no matter 

 from what quarter the wind blows, here reigns perfect tranquillity, an 

 essential ingredient in producing great animal development. Another 

 physical fact is worth noticing — frost or snow, when they do occur, 

 seldom last longer than twenty-four hours, and they require to be severe 

 to continue so long ; and so very mild in general is the weather on this 



