Christy : Ferns of the Neighbourhood of York. 179 



was found at Castle Howard in September, 1877, and I have found it 

 inclining towards this variety at Hagg Farm Wood. 



Asplenium ruta-muraria. — A common enough fern to those who 

 search for it in our district. In my examination of the city walls I 

 found it in abundance. It grows finely on an old wall by the Earl of 

 YarbOrough's, on some old walls at Copmanthorpe, on St. Olave's 

 Church and the surrounding walls, on old walls near Lendal Bridge, 

 finely but not abundantly on the old wall forming the back of the 

 Castle, also at Kexby, Sutton-on-Derwent, Acomb, and Skipwith, but 

 finest of anywhere that I have seen it round York, though scarce, on 

 the old boundary wall of St. Mary's Abbey, which now forms the 

 backs of the houses on the left hand side of Mary gate going down. 

 That which grows on the city walls principally does so on the south 

 and south-west sides of the city. At the following places it abounds, 

 while it occurs more sparingly at many other spots : — On the inner 

 side over the Old Station, between the Station and Micklegate Bar, and 

 between there and the corner. Whether it be a general rule or not I 

 cannot say, but I have observed, almost wherever I have found this 

 plant in the York district, that it seems to have a great objection to 

 growing on an unprotected north wall. The only places where I have 

 seen it growing with an unprotected and direct northerly facing are, a 

 single plant overlooking Cherry Hill, another close to the Iron Works, 

 and several overlooking Lord Mayor's Walk — all on the outside of 

 the city walls. It used to be said that it would only grow in the 

 mortar of a stone wall, but I have seen it many times on brick. The 

 seedling frond is kidney-shaped. There being no natural rocks in situ 

 in the immediate vicinity of York, I should imagine that the spores 

 have probably been brought with the stones from other districts. 



Asplenium Trichomanes. — Castle Howard (H. Ibbotson), Kexby. I 

 found seven or eight small plants growing on the city walls between 

 Micklegate Bar and Victoria Bar, but they have, I believe, all dis- 

 appeared now. Mr. Backhouse suggests that the spores would very 

 likely have been introduced with the stone. 



Asplenium Adiantum-nigrum . — Castle Howard (H. Ibbotson). One 

 plant was found near York many years ago (S. Thompson). The 

 rarity of this species surprises me. 



Atliyrium filisc-fcEmina. — A very variable species. The midrib is often 

 pink. The fronds frequently attain a huge size ; at Askham I have 

 measured one 3ft. Sin. long, in Overton Wood 4ft., and at Castle 

 Howard I found one in a marshy spot under bushes measuring even 



