236 Marine Algce of Berwick-on-Tweed. 



to gx'eeii. The filaments are about 021 mm. in diameter, 

 straight or slightly curved gradually tapering into an obtuse 

 point. The articulations are about three times as broad as lung. 



Oscillaiua colubrina, Thur . 



In Le Jol., Liste des Alg. Mar. Cherb., p. 26. 



Descr. et Fig. Oscillaria colubrina, Le Jol., I.e., pi. i., fig. 2. 



JSxsicc. ,, ,, Le Jol., Alg. Mar. Cherb., no. 216. 



Hab. On mad-covered rock at half-tide level and in caves- July— 

 Oct. Rare. Caves north of Dodd's Well, Needle Eye. 



The filaments of this species are regularly flexuous, a character 

 which they retain in drying. The plant forms blackish-green 

 or purplish strata on mud-covered rocks in the shade. In the 

 caves north of the target at Dodd's Well and near the Needle 

 Eye it grows over the cushion-like patches of Sphacelaria radicans 

 and Cladophora arctiuscidii, the filaments of the Oscillaria inter- 

 lacing with those of the plant over which it grows. So far as 

 my observations have gone, the plant does not form layers of 

 indefinite extent, as so many of the other species of Oscillaria 

 do, but has a tendency to grow in small roundish patches hardly 

 half-an-inch in diameter. It imparts to fresh water a copious 

 pink dye, the colour of the filaments themselves changing to a 

 bright emerald green. The filaments are about -018 mm. in 

 diameter, obtuse at the ends, the articulations four times as 

 broad as long. 



Oscillaria ins ignis, Thwahen, 



In Ifarv., Phyc. Brit., pi. 251c. 

 Hab. On the muddy sea-shore, Fenham Flats and Holy Island. Local 



but plentiful. Aug.— Oct. 

 A pretty species forming blackish-green or brown layers of 

 indefinite extent. The apices of the filaments are obtuse and 

 ciliated, the articulations four or five times as broad as long. 



Uscillahia AMLiAiUA \Turgens, Ktz. 

 Phyc. Germ., p. 160, no. 28. 

 Exsicc. Oscillaria antliaria, Itdbenhorst, Alg. Europ., no. 208. 

 Hab. In pools of brackish water along the muddy banks of the 



Tweed above the railway bridge. Autumn. Rare. 

 This and the four following species usually grow in fresh 

 water, but as they are found at Berwick in company with 

 0. nigro-vindit, O.flavo-fusca, Grn., and 0. littoralit, Crn., which 



