501 



intracellular rhizoids on the contrary, grow downwards through tlic 

 underlying cells, nuicli in the same way ;is Rosenvinge 1 says is 

 the case with the basal cells of Chætomorpha; it is probably lliis 

 (aet, to which Kjell man alludes, when he says 2 Ihat the trans- 

 formation in the l>as;il pari of U. mirabilis corresponds closely with 

 that, which according to Rosenvinge, lakes place in Chætomorpha. 



Var. elongata Rosenv., Grønl. Havalg. (p. 918, fig. 35). Tliis form 

 which is distinguished by its elongated, not swollen cells, frequently 

 occurred among the main species with 

 which it seemed to be connected by a 

 series of very gradual transitional stages. 

 A fruiting filament was about 30 (i broad. 



This species occurs on rocks and 

 stones near high-water mark, especially on 

 exposed coasts where it is washed by the 

 waves. It grows gregariously, often asso- 

 ciated with U. Wormskioldii, Ulothrix flacca, 

 Bangia fuscopurpurea , etc. Sometimes 

 though rarely, it occurs as an epiphyte on 

 larger algæ, e. g. on Himanthalia lorea. 



Specimens with zoospores were ga- 

 thered between April and July and with 

 gametes in April. The latter which are 

 much smaller, are elongated and have two 

 cilia; cells with the latter as well as those 

 with zoospores are often found intermixed 

 in the same filament. Specimens gathered 

 by Helgi Jonsson in November seemed 

 to be sterile. 



This species, which is undoubtedly eoin- 

 iiion along the coasts of the Færoes, has hitherto been gathered on 

 Str.: Thorshavn, in many piaces abundantly (!) , Kvivig (Lyngb.); Syd.: 

 Frodebo (!), Yaagsejde (!) ; M y g g e n æ s (!) ; Lille Dimon (!). 



As mentioned above, it had already been gathered by Lyng- 

 bye, since it occurs intermixed in his material of Conferva flacca 

 in his herbarium. Lyngbye's Conferva hormoides is also beyond 



1 Kolderup Rosenvinge, L.: »Om nogle Væxtforhold hos Slægterne Clado- 

 phora og Chætomorpha (Botanisk Tidsskrift, 18. Hind. København 1892 . 



2 Kjellman, F. R.: Blastophysa polymorpha och Urospora incrassata, två 

 nva Chlorophyceer Iran Sveriges vestra kust (Bihang till K. Svenska Vet.-Akad. 

 Handlingar. Band 23, Aid. III, No 9. Stockholm 1897, p. 13). 



32* 



Fig. 100. Urospora mirabilis Aresch. 

 Basal portions of 2 young piants; a 

 with extracellular ;md intracellular rhi- 

 zoids; /> with intracellular rhizoids 

 onlv. 200: 1. 



