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Dublin Natural History Society. 



At the usual monthly meeting of this Society, held on Thursday, 

 after several zoological papers had been read, 



Mr. Kinahan exhibited a plant of a fern, a variety of Polystichura 

 aculeatum, found by him at Bohernabreena, county Dublin, in 1849, 

 which in 1850 was handed over to the care of the College Botanical 

 Garden, where it had thriven, but had not exhibited seed-vessels as 

 yet, though possessing a tendency to throw out bulbillae. Mr. Kina- 

 han remarked on the general redundancy of form in the ferns, and 

 exhibited specimens, and referred to this as the only known example 

 of the reverse, and gave the following statement : — " The example of 

 Polystichum aculeatum now submitted to your Society is curious, as 

 being an exception to the law which seems generally to prevail among 

 the ferns as regards varieties. These generally differ from the typical 

 plant, by having something added to them, either an actual expansion 

 or a subdivision of the typical parts. Of this we have a very good 

 example in those varieties of Athyrium Filix-foemina, to which the 

 name of viviparae has been given, in which we find tassels appended 

 to the pinnae. We also have a good example of it in the variety of 

 Polystichum angulare obtained at Ballinteer, in this county, in which, 

 as you see, the pinnae, particularly near the upper extremity and the 

 frond, are enlarged, so as to give a more expanded appearance to the 

 entire frond. Now let us contrast these with the variety to which I 

 first drew your attention, as the great difference must strike you at 

 once. In this we find the broad pinnae of the type replaced by nar- 

 row, linear leaflets in some of the fronds, resembling spines or points; 

 while in others they have totally disappeared, especially at the upper 

 half of the frond, which in many presents a long filament, totally des- 

 titute of any pinnae. These appearances have continued constant 

 under cultivation, as must be evident if we compare the plant now with 

 these fronds taken from it in August, 1849, when I found it growing 

 on slate rocks by the side of the stream which, running through Frairs- 

 town-House demesne, falls into the Dodder just above Bohernabreena. 

 This glen seems favourable to the growth of varieties, as I also ob- 

 tained there these specimens of Aspidiura Filix-mas. Varieties of 

 fern are, indeed, commoner than many think, in particular places 

 abounding almost to the exclusion of the ordinary type. Thus, at 

 Kilmaganny, county Kilkenny, the variety of the common hart's- 

 tongue, to which the name of ramosura has been given, is far commoner 



