15 161 Proceedings of the Royal Irish Academy. 



so may have been overlooked ; but most of the southern records of this plant 

 prove to be errors for Ptinctaria tcnuissima. It is also known from the 

 Faeroes, Kiel, and W. Sweden. 



Phyllophora Brodiaei. —See note on p. 134. The plant is known from Nova 

 Zemblya, Spitzbergen, E. Greenland, Iceland, Norway, Sweden, Baltic, 

 Scotland, N. England, and N. Ireland, and may therefore claim to be a dis- 

 tinctly boreal species. In Clew Bay it is scarce, but several colonies were 

 noted at Mulranny. 



Lithothamnium norvegiciim. — Scattered amongst L. calcarciim in Clew Bay 

 and at Roundstone. Known from Scotland, Norway, Denmark, and the N. 

 Atlantic coast of N. America. It has not been observed in the Lithothamniuni 

 banks of the English or French coasts. 



Lithot ho milium compaction. — Madame Lemoine remarks that this is a 

 distinctly boreal species. It is known from Nova Zemblya, Spitzbergen, 

 Iceland, Norway, Greenland, and the N. Pacific coast of N. America. 



Callithamnion arbuscula. — The presence of this boreal species on the 

 Irish west coast gives the appearance of a distinct overlapping in the flora. 

 In the colder waters of the North Sea it is not known south of Yorkshire ; ! and 

 on the west coast of Great Britain it descends to Ayrshire and the Isle of 

 Man. On Clare Island it is abundant, and forms a conspicuous belt, just as 

 it does in Scotland, Norway, and the Faeroes. It is recorded by Adams for 

 Munster and Leinster, and probably extends right round the Irish coast. 



Ptilota plwmosa .— Another anomaly on the west coast. Listed by Borgesen 

 as a sub-arctic species and general in Iceland, Nova Zemblya, and Spitz- 

 bergen, P. plwmosa descends as far as Yorkshire on our east coast, and North 

 Wales and the Isle of Man on the west. In Clare Island it is plentiful on 

 the stipes of Laminaria Cloustoni, and is washed ashore in company with 

 such southern plants as Taonia and Callymmiu reniformis. Adams lists it 

 from Munster and the south of Ireland ; but as the older writers often con- 

 fused the plant with Plumaria. elegans, it would be advisable to confirm its 

 presence in the southern provinces. In the London herbaria, there are no 

 specimens south of Ilenvyle (Co. Galway). 



(e) Other interesting species. — The most noteworthy alga in the list 

 is undoubtedly Codium mucronatum var. atlanticum. This had either to be 

 regarded as a new and endemic species, or to be linked with the Australasian 

 C. mucronatum. The agreement in microscopic structure with the latter was 

 found to be so close, that it was impossible to do otherwise than regard it as a 

 form of that species. Its position on the west coasts of the British Isles is, how- 

 ever, remarkably isolated, as it is not known elsewhere in Europe, nor indeed 



' Batters gives an Isle of Wight record ; but this is almost certainly an error for C. granulatum, a 

 compact form of which is not uncommon in that locality. 



