Marine Algce of Berwick-on- Tweed. 235 



OSCILLARIA SUBULIFORMIS, T/lWditeS, 



in Hare. Phyc. Brit. pi. 251b ; Farlow, Mar. Alg. New Eng., 

 p. 33, pi. r., fig. 5. 

 Rah. On the muddy sea-shore at the mouth of the Tweed, in the Cares 

 north of Dodd's Well, and elsewhere along the coast. July — 

 Oct. Not uncommon. 

 The filaments in this species are from "006 — -007 mm. in 

 diameter and taper at the end into an incurved point. The 

 colour is bluish-green, rather brighter than in the preceding 

 species. 



Oscillaria l^etevirens, Crouan, 



Liste des Alg. Mar., Bullet. Soc. Bot. de France, 1860 ; Cm., 

 Flor. duFinist., p. 112. 

 Sab. On the under side of overhanging mud-covered rocks. Rocks in 



front of Dodd's Well. Greenses. June — Nov. Hare. 

 This plant forms a thin, bright green, membranous stratum 

 on mud-covered rocks often in company with Catenella Opuntia. 



The filaments are very sleuder and obtuse at the ends, the 

 articulations about as long as broad. 



OftOILLARlA NIGRO-VIRlDltt, Thw . 



in Harv., Phyc. Brit. pi. 251 a. 

 Exsicc. Oscillaria nigro-viridis, Crouan, Alg. Mar. Finjflt., no. 32b\ 

 Hal. Banks of the Tweed from the mouth to the Plantation 



Autumn. Common. 

 Forming dark olive-green, almost black, slimy layers on mud 

 and mud-covered rocks, piles, etc. The diameter of the fila 

 ments is from -009 — -010 mm. When dry the dark olive 

 colour of the living plant changes to a rich metallic green. 



Oscillaria percxjrsa, var. marina, Ktz. 

 Sp. Alg., p. 247. 

 Descr. Oscillaria flavo-fusca, Cm., Flor. du Finist, p. 113. 

 Exsicc „ ., ., Alg. Mar. Finist., no. 328. 



Hah. On the muddy bottoms of shallow pools near high-water mark. 

 Aug. — Sept. Rare. Berwick Bay. Banks of the Tweed below 

 the old bridge (mixed with other species of Oscillaria, such as 

 O. nigra- cirid in and O. natavs.) 

 This plant forms slimy, brownish-yellow layers, which after 

 a time, become detached from the mud on which they grow and 

 float to the surface of the water. In drying the colour changes 



