258 OSCILLATORE^E. 



d. Filaments brown, brittle, not coriaceous. 

 24. OSCILLATORIA DlCKIEI HdSS. 



Plate LXXII. Fig. 13. 



Char. Stratum light chestnut, gelatinous, glossy. Filaments 

 long, straight, brittle, rather thick. Striae visible, sub- 

 distant. 



Hob. Pools of fresh water near the sea, Aberdeen : Dr. 

 Dickie. 



The colour of this species is so peculiar as at once to dis- 

 tinguish it from all others which have been described. This 

 colour is preserved in drying ; the filaments are of nearly the 

 same diameter with those of O. tennis, but they preserve their 

 calibre when dried. Several fine specimens of this plant 

 were sent me by Dr. Dickie, and which have undergone no 

 change since they have been in my possession, now some 

 weeks. 



e. Filaments collected into close erect tufts. 



In the species of this division of the genus there would 

 appear to be an evident transition to Rivularia, the filaments 

 in one, O. lucifuga, and perhaps in the others, being subulate, 

 and which circumstance induced me, as well as its erect 

 habit, to place that species in the genus Rivularia. I am now 

 satisfied that it should either remain in the division of the 

 genus Oscillatoria in which it has been placed by Mr. 

 Harvey ; or that Kiitzing's Symploea ought to be adopted for 

 the reception of the species of this division of Oscillatoria. 

 Kiitzing thus defines the genus : 



Trichomata adscendentia vaginata in fascicules erectos, basi 

 confluentes, coalita ; vaginae ex membrana simplicima, hyalina, 

 (nee striatae nee lamellosas) formatae. 



25. OSCILLATORIA FRIESII Ag. 



Char. Stratum bright green, bristling with the elongated, erect, 

 tooth-like fascicles of filaments. 



