282 NOSTOCHINE^. 



gree of a voluntary character, and whether the explanation 

 given of the elevation to the surface of the waters of almost all 

 the Conferva is not sufficient to account for that of the Ana- 

 baince. The explanation alluded to is the fact that during 

 respiration a gas is eliminated, the globules of which be- 

 coming entangled in their filaments, renders them specifically 

 lighter than the water, and so causes them to ascend. 



1. ANABAINA FLOS-AQU^E Bory. 

 Plate LXXY. Fig. 2. 



Char. Filaments large, beautifully moniliform, and variously 

 curved. Reproductive cells numerous, elongated, and for 

 the most part curved. 



Nostoc flos-aquce Lyngb., Dan. p. 201. t. 68. Anabaina 

 fas-aqua Bory ; Hudson, Flor. Ang. p. 604. ; Light. 

 Scot. p. 999.; Harvey in Manual, p. 186. 



" This species attracted my attention when tinging with 

 its delicate green hue the margin of the smallest (?) of the 

 lochs Maben in Dumfries-shire, or that nearest to Jardine 

 Hall (on the road from the village of Lochmaben), as I drove 

 thither on the 15th of August, 1838. The day was calm and 

 bright. My specimens tinge the paper with a verdigris 

 colour, and are quite dull, or wanting in any lustrous ap- 

 pearance. This species is introduced here on account of its 

 having been erased of late years from the British Flora. 

 Hudson and Lightfoot included it without assigning to it 

 any British station or locality." Thompson. The repro- 

 ductive cells, which, as noticed in the definition of the 

 species, are curved to accommodate themselves to the various 

 curvatures of the threads are mostly solitary, and I have 

 never observed more than two contiguous to each other. 



2. ANABAINA LICHENIFOKMIS ? Bory. 



Plate LXXV. Fig. 4. 

 Char. Filaments not moniliform, minute, but little curved. 



