Clare Island Survey — Marine Algae. 15 109 



Clew Bay, where the water is quiet and muddy ; but here it is local, and not 

 generally distributed. On the bridge near Murrisk it was noted attached to 

 mussels, as at Belfast and Southampton. 



ULOTHRIX. 



The species of Ulothrix were kindly determined by Dr. N. Wille. Two 

 new species are added to the British flora, but one of these may represent the 

 plant named by Batters U. implexa. 



U. flacca Thur. 



Common on the flat sheltered shore of the mainland, but not found on 

 Clare Island, the plant of exposed coasts being now regarded as a distinct 

 species — viz., V. pseiidoflacca "Wille. 



On my February visit especially. U. flacca was found in thin, felt-like 

 masses, just below high-water line, on the muddy shores of Clew Bay and 

 Achill Island. The filaments usually measured 40-50 /u diam. ; and the cells 

 contained a large ring-like chromatophore with 4-6 pyrenoids. U. flacca is 

 not listed in the " Synopsis/' but Mr. Adams tells me that the plant was 

 included as a synonym of Vrospora isogona (see Urospora mirabilis). 



U. consociata Wille. 



Apparently common in the district during winter and spring. It was 

 found on boulders near high-water line at Portlea, and was abundant at 

 Eoonah iu similar positions during February. Collins ('09, p. 186) designates 

 this species TJ. laetevirens (Kiitz.) Collins. 



TJ. pseudoflacca Wille. 



Not previously recorded for the British Isles, though doubtless passed 

 over as U. flacca. On Clare Island it is the dominant species of the Bangia- 

 TJlothrix-Frospora association, and is also frequent as an epiphyte on various 

 algae, especially the stems of Fucus vesiculosuS. On Alnahaskilla it formed a 

 dense and tangled coating on Lichina pygmam. 



TJ. subflaccida Wille. 



To this species a very slender plant, found on muddy stones near high-tide 

 level, is referred by Wille. The filaments are only 7-10 fi diam., and possess 

 band-like ebromatophores, with one pyrenoid. From the description given 

 by Batters ('89, p. 35) it appears probable that it is the plant referred by him 

 to TJ. implexa Kiitz. ; but Professor Wille informs me that it is quite impossible, 

 from the meagre description, to determine the identity of Kiitzing's species. 



Bunoweu River and Achill Sound, February, 1911 



