104 OSCILLATORIACE^ 



7. Lyngbya hyalina, Harv. ; filaments basifixed, erect, straight, very slender, 

 arachnoid, gelatinoso-membranaceous, flaccid, very pale yellowish green or nearly hyaline • 

 endochrome filling the tube, at first granular, then annulated. (Tab. XLVII. G.) 



Hab. On lime encrusted rocks at Key West, W. H. H. (v. v.) 



Forming indefinite, very soft and sub-gelatinous continuous tufts or pilose strata. 

 Filaments fixed by their base to the rock, and floating freely, exceedingly slender and 

 cobwebby, straight, glossy, cylindrical, from half an inch to an inch long, very pale 

 jeruginous or yellowish-green, often nearly colourless. The cell-wall is thin and delicate, 

 and the endochrome quite fills the tube, leaving no perceptible margin. 



I do not know any species similar to this. It is exceedingly slender and delicate. 



Plate XLVII. G. Fig. 1. Lyngbya hyalina, the natural size. Fig. 2. Portions of 

 three filaments, magni^ed. Fig. 3. Section of a filament, highly magnified. 



8. Lyngbya muralis, Ag. filaments somewhat rigid, thickish, tortuous, very long, 

 interwoveninabright, grass -green stratum; annuli strongly defined. Ag. Syst. p. 74:. 

 Harv. Man. Ed. 1, p. 160. Conf. muralis, Dillw. tab. 7, E. Bot. 1. 1554. /3. aquatica. 



Hab. var. /3, in pools of fresh water, Whalefish Islands, Davis Straits, Dr. Lyall. 

 (v.s.) 



The specimens are mixed with turfy soil. Except in the submerged habitat, this 

 agrees with the ordinary form. Intermixed with threads of the usual size and structure 

 are others cohering in pairs, as in L. copulata, Hass., which is obviously only a state of 

 this widely dispersed species. I have not received specimens of the ordinaiy L. muralis 

 from America ; but no doubt it is common on damp walls, &c.j as in Europe generally. 



IV. CALOTHEIX, Ag. 



Filaments destitute of a mucous layer, erect, tufted, or aggregated, fixed at the base, 

 somewhat rigid, not oscillating. Tube continuous ; endochrome green, densely annu- 

 lated, at length separating into lenticular sporidia. (Marine or in fresh water.) 



I retain the genus Calothrix, as established by Agardh, in preference to dividing it, 

 with Kiitzing and others, into the groups Leiblinia, Tolypothrix, ^c. which appear to 

 me to be separated on very uncertain and variable characters. The whole group 

 requires a careful study and complete remodelling ; but I have neither time not sufii- 

 ciently copious materials to attempt such a work. I can hardly suppose that the 

 multitude of species and genera of these obscure plants described by Kiitzing are all 



