840 Fresh-water Algce of Canada. 



This species is, in its young state, of a bright beautiful green, 

 very gelatinous, delicate, and fragile. As it becomes mature, it 

 changes to a green olive. It is a very elegant, and, as a micros- 

 copic object, possesses great beauty. The branches are long and 

 graceful, and the head-like form of the cells give them a sparkling 

 gem-like lustre. 



II. D. CONDENSATA, HaSS. 



Char. — Filaments of considerable size, sparingly branched. 



Branches only occasionally compound, short, with short cilia. 



Cells abbreviated. 

 Hassall in Annals of Nat. His. Vol. XI., p. 429. Hist. Brit. F. 



Algce, p. 122, Plate XL, fig. 1. 

 Hab. — In the quiet and clear waters of the St. Lawrence ; found 



in spring, while the ice was upon the river, at the steamboat 



wharf, Morrisburg. 

 This species is described as one of the finest and most distinct 

 of the genus. There is no difficulty whatever in recognising it. 

 It is very sparingly branched. The ramuli are never tufted; 

 irregular in length ; occasionally very short ; and the cilia are 

 rarely prolonged. Only in the locality mentioned have we found 

 this species. Our specimen when found was of a lustrous green 

 color. In the diy state it has taken a yellowish tinge. 



III. D. tenuis, Ag. 

 Char. — Filaments slender ciliated, moderately branched. Branches 



usually simple and solitary, but sometimes sub-fastigiate. 



Cells of the stems twice or thrice as long as broad ; those of 



the branches rathe? longer than broad. 



HassalPs Hist. Brit. F. Algce, p. 123. 

 Hab. — The rapid streams which run through the railway pier at 



St. Lambert, Montreal ; also at St. Helen's Island. 

 This species is very tenacious, and is an inhabitant of streams 

 and rivulets the current of which is strong. It is found in great 

 profusion and beauty in the localities referred to. Its bright 

 green fronds fringe the rocks, stones, and drift-wood, and add 

 brilliancy to the rushing waters. The filaments are very long, 

 and are as hardy as the Cladophera glomerata. The branches are 

 irregular or alternate, more or less furnished with scattered ramuli 

 whose tops are either acute or drawn out into long setaceous 

 colourless points. Harvey in his Manual says that at first the 

 filaments are enclosed after the manner of Chcetophora in a com- 



