282 3. Humida. i . HYDROPHYTE. Pl. cell aph . 
1. Humida muralis . IVall humida . 
Threads green, rather stiff, bent, twining, rather thick, 
entangled so as to form a close green matt. 
Conferva muralis, Roth Cat. 3, 187 ; Dillw. 7; Engl. Bot. 1554. 
Conferva rigida, Roth. Cat. 1, 166. 
Oscillatoria parietina, Vouch. 196, 
Oscillatoria muralis, Agardh Disp. 1, 27. 
Garden-walls, damp areas; all winter. 
2. Humida decortieans. Slip-coat humida . 
Threads very slender, bluish green, bent, entangled into 
a very close green mat. 
Conferva muscosa confragosa rivulis innascens, Dillen. Muse. 15. 
Conferva confragosa, Lightf. Scot. 976. 
Conferva violacea, Hudson FI. Angl. 592. 
Conferva decortieans, Dillwyn , 26. 
Oscillatoria decortieans, Lyngbye IJydr. Dan. 95. 
Damp woods and bark of trees; summer. 
Threads three times as slender as those of humida muralis. 
3. Humida cyunea. Sky-blue humida . 
Threads very slender, glaucous blue, covered with a de- 
ciduous coat, entangled into a close sky-blue mat. 
Conferva cyanea, Engl . Bot. 2578. 
Oscillatoria cyanea, Agardh Disp. ed. 2, 33. 
Damp walls and stones. 
IV. 4. ELISA. Elisa . 
Threads simple, rarely adhering to one another, as if 
branched, membranaceous, gelatinous, upright, tufted, free, 
not oscillating, nor lengthening. 
1. Elisa fontinalis . Spring elisa. 
Fresh ivater ; threads simple, very slender, nearly hyaline, 
rather stiff, upright, short, forming a dark green mat. 
Conferva fontinalis fusca omnium minima mollis, Dlllenin Raii Syn. 58. 
Conferva fontinalis, FI. Dan. 651 ; Engl. Bot. 2054. 
Oscillatoria fontinalis, Agardh Syn. 110. 
Stones and posts in water ; summer. 
Tufts very small, dark or light green ; threads aggre- 
gated, a quarter of an inch long, straight; adheres to paper. 
2. Elisa bicolor . Tiuo-coloured elisa. 
Fresh water; threads simple, slender, bright green, 
weak, very long, forming a bright green fluctuating mat. 
Conferva bicolor, Engl. But. 2288. 
