Marine Algce of Berwick-on-Tweed. 237 



have always been classed with Marine Algae, I can see no valid 

 reason for omitting them from this list. It is always a difficult 

 matter to determine which species of Oscillaria should be con- 

 sidered marine and which fresh water Algrc. I have only 

 admitted those species which grow within the influence of the tide. 



OSCTLLARIA NATANS, Kt%. 



Phyc. Germ., p. 159, no. 10. 

 Descr. Oscillaria nutans, Etz., I.e. 



Fig. Oscillaria cryptartha, Ktz., Tab. Phyc. I. t. 40, fig. 4. 

 J£ab. Mixed with other species of Oscillaria, such as O. fiavo-fusco. 

 0. nigro-viridis, etc., on the muddy bunks of the Tweed between 

 the bridges. 

 A more slender species than any of the preceding, the fila- 

 ments being from "005 to "0053 mm. in diameter. 



Oscillaria infecxoria, Tassi, 



Erbario crittog. Ital., no. 448. 

 Hab. Mixed with the preceding in pools of brackish water, and on the 

 muddy banks of the river. The filaments are only about 

 '00125 mm. in diameter. 



Oscillaria brkvis, Rabenh. 

 Alg. Europ., no. 30. 

 Hab. Banks of the Tweed with the two preceding species. 



Oscillaria tenuis, b. viridis, Rabenh. 

 Alg. Europ., no. 1016. 



Hab. Mixed with the preceding. 



The nomenclature of the Oscillaruv is still far from settled, and 

 no synonyms have in consequence beeu affixed to many of the 

 species. In most cases a reference is given to a published 

 specimen, and the names adopted imply that our plants belong 

 to the same species as the specimens referred to, but not neces- 

 sarily to other specimens described under the same name. For 

 maii3 r of the measurements and references I am indebted to M. 

 Gxunont. 



MICROCOLEUS, Desmaz. 



Microcoleus chxhonopl.ystes, (Fl. Dan.) Thuret. 



Classif. Nostoc, I.e., p. 378.— -Conferva chthonoplastes, Fl. 

 Dan. t. 1485. 



