- 363 - 



the sporangia and the vegetative cells are for the most part of a cylindric 

 shape, but indistinctly tumid sporangia or cells are however not rarely 

 occurring. The sporangia are usually about as long as broad or up to 

 about 1 V2 times longer than broad. Sporangia, which are up to 4 times 

 longer than broad are more rare. My specimens are richly furnished with 

 rhizoids at the base. In many cases up to 10 or more cells of the lowest 

 part of the filaments have produced rhizoids, one each. The rhizoids are 

 for the most part secund, but I have also occassionally seen alternate 

 rhizoids somewhat reminding of the figure given by Areschoug (Obs. Phyc. I, 

 Tab. Ill, fig. 9 x )) of Urospora mirabilis. The rhizoids grow downwards 

 either more or less touching the surface of the filaments, or they do not 

 touch it especially the uppermost rhizoids, which are separated from the 

 filaments by wider angles and grow downwards in oblique direction some- 

 times comprehending other filaments by the incurved apex. I have also 

 occasionally seen rhizoids occurring singly far above the rhizoid-bearing 

 lowest part of the filaments, either touching the surface of the plant or 

 not. The rhizoids of all my plants are extramatrical, and intramatrical 

 rhizoids, as described in U. mirabilis (see above p. 360), do not occur. 

 Regarding the structure and the substance of the membrane, my plants 

 fully agree both with Rosenvinge's original specimens of U. Hartzii and 

 with Urospora mirabilis (see above p. 360). The cells of my plants 

 contain a single reticular chromatophore of a sack-like shape resembling 

 the figures given by Rosenvinge (1. c. fig. 38, A, B). The largeness of 

 the meshes of the chromatophore varies also in this species (cfr. above 

 p. 361) and younger cells contain chromatophores with considerably smaller 

 meshes than figured by Rosenvinge. Fructiferous specimens have been 

 gathered in April — June ; regarding the shape of the zoospores my 

 specimens agree well with the Greenlandic plants (Rosenv. 1. c. fig. 38, D). 



Although Urospora Hartzii Rosenv. is insufficiently known, as the 

 original specimens described by Rosenvinge were destitute of the base, I 

 have referred my specimens to it, as the upper part of the filaments of 

 my specimens agrees precisely with the Greenlandic plants. Urospora 

 Hartzii seems to have en intermediate position between U. mirabilis and 

 U. Wormskioldii, it differs from the former in wanting the intramatrical 

 rhizoids and by the bigger size, from the latter by its smaller size, by 

 the shape and the shortness of the cells and the substance of the mem- 

 brane. Moreover the difference between the thickness of the filaments 

 below and above is far greater in U. Wormskioldii than in U. Hartzii. 



*) This figure, I think, stands inveised and the branches are doubtless to be 

 regarded as rhizoids. 



