— 356 — 



better conserved material both of Bangia virescens Fosl. and of the Ice- 

 landic variety of U. consociata is at hand, it must be left undecided, 

 whether they are identic or not, but I think that B. virescens will turn 

 out to be a species of Ulothrix most nearly related to U. consociata Wille, 

 f. geniculata nova forma. 



It forms a matted growth of light-green colour on rocks at high- 



Fig. 8. Ulothrix consociata var. islandica f. geniculata. a (300:1) a fragment 

 of a sterile filament; b (550: 1) showing the lateral nuclei; c (311 : 1) a portion 



of a filament showing a sporangium. 

 Fig. 9. Ulothrix consociata var. islandica f. geniculata. a, b, c fragments of 

 filaments showing the shape of the chromatophore and the lateral pyrenoid. 



(311 : 1.) 



water mark. The filaments are 13 — 15 thick, either straight or irregu- 

 larly curved and not rarely kneed at more or less regular intervals. I 

 have not seen basal rhizoids, but short, lateral rhizoids usually occur at 

 the knees of the filaments either singly or two together. I have occasion- 

 ally seen somewhat ramified filaments, some of the branches are, I think, 

 to be regarded as articulated rhizoids. The branching occasionally reminds 

 somewhat of the ramification of Rhizoclonium as a part of the filament, 

 replaced by the rhizoids, apparently becomes lateral. My specimens are 

 generally unbranched, and I suspect that the branching must be regarded 



