502 



doubt referable to this species, though no specimens from the 

 Færoes are to be found in his herbarium. He writes with reference 

 to it (Hydrophyt. , p. 145): — »Habitat ad littora Færoensia, saxis 

 maritimis in summo refluxus limite adnata, copiose«. Rostrup 

 (1. c. p. 88) calls it Hormiscia penicilliformis (Roth) 

 Fr. on the faith ofLyngbye's record, and finally 

 Simmons (1. c. p. 274) calls it Ulothrix isogona 

 (Engl. Bot.) Thur. and records it as probably 

 fairly common without, however, naming the 

 habitat. 



181. U. Wormskioldii (Mert.) Rosenv., Grønl. 

 Havalg. , p. 920; Chætomorpha Wormskioldii 

 Kjellm., N. I., p. 384 (313). 



The base of this species — fig. 101 shows 

 the lower part of a young plant — consists of 

 a more or less large disc formed by numerous 

 intertwined rhizoids, which spring from a fairly 

 considerable number of cells situated in the ba- 

 sal portion of the plant, these rhizoids grow 

 downwards along the cell-wall, attaching them- 

 selves to the sides of the filament. The single 

 cells in the portion of the filament thus covered 

 by the rhizoids are on the whole distinctly dis- 

 cernable right down to the base. These rhizoids 

 closely resemble the extracellular rhizoids of 

 U. mirabilis, but the intracellular rhizoids of the 

 latter are wanting in U. Wormskioldii. 



The chromatophore, as found in a well- 

 developed cell, has the shape of a very richly 



Fig. 101. Urospora Wormskioldii 



(Mert.) Rosenv. Base of piant and fiiiely reticulated parietal plate, with nu- 

 merous small pyrenoids, and in a young cell 

 it occurs as an almost unperforated plate or 

 with a very few holes only, and fewer pyrenoids. The chromatophore 

 of U. mirabilis is more dense and of a darker colour and has eoin- 

 paratively few, but larger pyrenoids. Wil le' s figure (77«) in his 

 synopsis of the Chlorophyceæ in Engler und Prantl: »Die natur- 

 lichen Pllanzenfamilien« gives a good representation of a young 

 cell; in older more developed cells of U. mirabilis the chromato- 

 phore is richly perforated and is almost quite reticular. 



with numerous downward 

 growing rhizoids. 40 : 1. 



