THE GREEN ALGAE OF NORTH AMERICA 307' 



dull orange ; diam., including wall, 15-25 p. ; stipe rather short, 

 distinctly annulate. Growing among various algae, mostly blue- 

 green, in crusts near high water mark. Fig. 105. Me. Europe. 



Much like U. insignis, and perhaps rather to be considered a 

 small marine form of that species ; in its early stages not unlike 

 Gloeocystis zostericola . 



Var. FERRUGINEUS L,agerheim, 1882, p. 75, PI. Ill, figs. 31- 

 33. Rusty yellow ; larger than the type, up to 90 /j. with wall. 

 Greenland. Northern Europe. 



28. DACTYLOTHECE L,agerheim, 1883, p. 64. 



Cells cylindrical or oblong-ellipsoid, straight or slightly 

 curved, with rounded ends, solitary or 2-4 united into a family, 

 with broad, lamellate, persistent membrane ; chromatophore 

 parietal, occupying 73 of the cell wall, without pyrenoid ; 

 asexual reproduction by division in one direction only. Fresh 

 water. 



Like Gloeocystis, except for cell division being in one direction 

 only, with consequent difference in the shape of the cells and 

 families ; reproduction by zoospores and akinetes has not been 

 observed. 



D. CONFLUENS (Kiitz.) Hausgirg,* 1888, p. 140; Gloeothece 

 confiuens Nageli, 1848, p. 58, PI. I.G, fig. i ; Wolle, 1887, p. 325, 

 PI. CCX, fig. 6; Phyk. Univ., No. 483^ Cells 1.5-2.5 /, diam., 

 1/4-3 diam. long, with ample membrane, in few-celled families, 

 10-15 /A diam. Forming a gelatinous, yellowish or flesh-colored 

 layer on rocks. Fig. 118. Mass. Europe. 



29. GLOEOCYSTIS Nageli, 1848, p. 65. 



Cells spherical, with bell-shaped chromatophore, covering 

 most of the cell wall, and one pyrenoid ; wall thick, more or less 

 lamellate ; asexual reproduction by repeated cell division, sev- 

 eral generations of cells often remaining enclosed in the original 

 mother cell wall, and the walls of the intermediate generations ; 

 also by biciliate zoospores, and by akinetes. 



A genus very closely resembling in appearance, cell division, 

 etc., the blue-green Glococapsa ; differing in structure and color 

 of contents and by the formation of zoospores ; the latter have, 



*The attribution of this name to Hansgirg may be open to question, as 

 he does not actually use the binomial. His words are "Zu dieser Gat- 

 tung diirfte Gloeothece confluens (Ktz.) Nag., (Gloeocapsa conjincns 

 Ktz. ) in Rabh. Alg. Exsicc., No. 1231, und wahrscheinHch auch noch 

 Gloeothece dis/ans Stiz. gehbren." There seems here to be involved, in 

 addition to the usual rules of nomenclature, the question as to the exact 

 signification of a German auxiliary verb. 



