248 NATURAL HISTORY SOCIETI OF DUBLIN. 



Cystopteris fragilis. — I have only met with this Fern upon the 

 western portion of this county. It is to he found, so far as I could 

 ascertain, only in the clefts of the Carboniferous Limestone, and oc- 

 curs in the quarry near the top of " Mennin Brae," close to the east 

 side of the road from Sligo to Derry, near Bridgetown. It grows 

 luxuriantly here ; so much so, that some plants are often sub-tri- 

 pinnate ; aspect northerly. Again, in the mortar joints of the para- 

 pets of an old bridge, on the back avenue of Brown Hall demesne, 

 near Ballintra, about a mile and a half from the last locality. I lay 

 before you some fronds, but regret that I have not better specimens in 

 my possession just now. Again, along the ridge of arenaceous lime- 

 stone, which runs along the west side of Lough Eske to Eglish Moun- 

 tain ; aspect, easterly ; elevation, 200 to 300 feet. Here, if this Fern 

 was inclined to forsake the limestone beds of the " yellow sandstone" 

 formation, we might expect to find it in the sheltered and moistened 

 primary limestone rocks of the "White Goat Glen," at the opposite 

 side of the valley, a mile away, for its distribution, to which there 

 must be abundant opportunity, but I never could (I do not say posi- 

 tively that it does not exist there) with the closest search find a trace of 

 it there. 



Asplenium trichomanes, which grows with the preceding in the former 

 locality spreads continuously over both limestone rocks. At the first two 

 localities it is accompanied by a small Cystopteris of a very dwarfedhabit, 

 the pinnae being closer and more blunt than in the larger plants, and 

 sometimes imbricated. They have all the appearance of maturity, and 

 are found in full fructification. For two years I have observed no 

 change in its habit under cultivation, though I will not insist here upon 

 its constancy. 



Lastrea oreopteris is to be met with in several localities, but a little 

 higber up on " Mennin Brae," on the very top of the hill, beyond the 

 C. fragilis localities, in a field perhaps about thirty yards from the 

 east side of the road, I met with vigorous plants, having the margins 

 of their pinnules recurved, as occurs in L. thelypteris. I find the same 

 in the last described locality for Cystopteris fragilis near Lough Eske. 



Hymenophyllum Tunbridgense. — While Cystopteris fragilis can be 

 said to choose only the arenaceous limestone beds of the "yellow sand- 

 stone system," this Fern is equally persistent in its adhesion to the 

 sandstone. It is to be found fruiting freely in the joints of the dislo- 

 cated coarse conglomerate beds at the base of the yellow sandstone 

 series, immediately over the Lough Eske habitat of Cystopteris fragilis, 

 and at the elevation of nearly 1300 feet — aspect, easterly. The spe- 

 cimens exhibited by Dr. Grimshaw at the meeting in last April were 

 found by a friend of mine in a somewhat similar locality — viz., the 

 western extremity of the yellow sandstone rocks at Crownard Moun- 

 tain, near Killybegs. Mr. Foot records* its close adhesion to a few 



*" Proceedings of the Natural History Society of Dublin," vol. iii., p. 10. 



