McArdle — On the B^epatkcB of the Sill of Hoicth. 117 



jurat%]cana differs from A. julacea by characters so slight that 

 it may well be the two are merely forms of a single species ; 

 as in. the analogous Blepharostoma trichopJiylla, where dioecious 

 and paroecious inflorescence certainly coexist. However that 

 may be, there is no evidence to show that either Swartz or 

 "Wahlenberg discriminated between the two forms, and did not 

 equally include the J. julacea oi Lightfoot, as well as J.juratz- 

 hana, under their name ' </. nivalis,'' so that, whether species 

 or variety, to Limpricht belongs the honour of first distin- 

 guishing J. juratzJcana by its inflorescence." The specimens 

 collected by me on Howth and two other stations, one of which 

 is very little above sea level, are remarkably different from 

 A. julacea in the smaller size and bright olive green colour, 

 and above all in tristichous arrangement of the leaves, which 

 like the Scotch specimens are cleft to f , with narrow, often 

 acuminate or triangular, segments. A. julacea is a truly alpine 

 plant, never found at low elevations, and is much larger ; the 

 young shoots often assume a silvery colour in conspicuous 

 patches, often more than 2 inches in depth, with the leaves of 

 the lower plane dark olive brown, closely adpressed to the 

 stem, and often imbricated so as to conceal it, deeply cleft to 

 f of their lecg-th into two acute segments. The following are 

 the localities in Europe known for the plant : — On the summit 

 of Warschneck Mountain, Upper Austria, alt. 2200 feet, 

 where it was found by Juratzka ; in Lapland, at Pitensis, in 

 Tjidtjalsk Mountains (Lindberg, 1856) ; in the Grimsel Alps, 

 Switzerland, along with Marsupella sphacelata (Schimper, 

 1847). On moist rocks below the summit of Ben Nevis, in 

 fruit, August, 1880 (Mr. W. West). Amongst the rocks at 

 the Baily Lighthouse, Howth; on Ireland's Eye; and on 

 Dalkey Island, Dublin Bay. liot previously recorded as Irish 

 that I am aware of. 



20. *Blepharostoma setacea (Webb), Mitt. Hook. Brit. Jung. t. 8. On 



turfy and damp boggy places ; abundant on the Sutton side of 

 the hill ; plentiful amongst the rocks near the Baily Light- 

 house, and is to be met with on most parts of the hill, often 

 mixed with species of Cephalozia and other Liverworts. 



21. Scapania undiilata (Linn.), Dill. Hook. Brit. Jung. t. 22. Side of 



a stream near the Lighthouse green, and on a small bog near 

 the Ballykill plantation. 



