DFBLIN NATURAL HISTOBT SOCIXTT. 195 



slightly convex form. Now, when I sec such characters invariably ac- 

 companied in the one case with entire marg:in8, in the other with deeply 

 serrated or almost spinulose ones, I cannot do otherwise but look upon 

 them as distinct as any two ferns can well be. I certainly remember 

 the time, years and years ago, when I hesitated, till I found on one and 

 the same rock in Argyleshire copious specimens of the two in great 

 tufts, but each retaining its own characters, and exhibiting nothing in- 

 termediate. It is quite true I have expressed doubts and difficulties 

 with respect to exotic specimens referred to the two ; but then we have 

 not the advantage of consulting recent specimens, or even good speci- 

 mens of those. Most botanists consider them distinct (the Wilsoni) 

 from ours. I cannot give up our British original ones. Prest places 

 them in two distinct sections, from the different nature of the involucre ; 

 but that is carrying the distinction too far. 



" Very faithfully yours, 



" W. J. HOOKEB." 



The Hon. Seceetary read the following — 



NOTES ON FRESH-WATER M0LLIT8CA IN THE NEIGHBOXTRHOOD OF ENNI8, AND 

 THE RELATION BETWEEN THOSE NOW LIVING THERE IN THE LAKES, AND 

 THOSE FOSSILIZED IN THE MARL, WITH OBSERVATIONS ON THE ACCIDENTAL 

 PRESENCE OF A MARINE SPECIES. BY FREDERICK J. FOOT, G. 8. I., COR- 

 RESPONDING MEMBER. 



About three miles to the north of Ennis, and less than a mile north- 

 east of Bally allia demesne, are situated several small loughs, abounding 

 in molluscs. These lakes communicate with one another by small 

 streams, and thus form a serpentine continuous chain. Formerly, after 

 heavy rains, the water used to rise to a considerable height, and flood 

 the neighbouring lands; but of late years the works of the Drainage 

 Commission have prevented this, and have also considerably reduced the 

 little loughs in size, so that a broad margin, three or four feet wide, of 

 what was formerly their bottom or bed, is now dry, and covered by num - 

 bers of dead shfells, the same as those seen living through the clear waters of 

 the lake. The most typical example of this phenomenon is seen at a small 

 pool called Licknaun Lough. Here myriads of shells are found sur- 

 rounding the scaly roots of the white and yellow water-lilies, which 

 spread themselves extensively over the dried-up surface and bed of the 

 lake. Specimens of these shells may be seen on the table. The follow- 

 ing is a list of them. I am indebted to my friend, Mr. "W. H. Bailey, 

 of the Geological Survey, for their identification : — Limnea stagnalxs^ 

 L. peregery Bithynia tentaculatay Succinea putrts, Planarhis marginatuSy 

 Neritina fluviatiliay Vahata pisctnalis, Anodonta cygnea, Cyclas cornea. 

 The same species are also found by digging into this dried margin. A 

 marine species, the common periwinkle (Littorina littorea)^ may be also 

 gathered here in abundance. The presence of these, which at first some- 

 what puzzled me, as these lakes are more than a mile from the Fergus, 

 and that river is only tidal to Ennis Mill, a point more than three miles 

 from the lake, is, I find, accidental, and due to the habit of the inhabit- 



2b 



