501 
intracellular rhizoids on the contrary, grow downwards through the 
underlying cells, much in the same way as Rosenvinge 1 says is 
the case with the basal cells of Chcetomorpha; it is probably this 
fact, to which Kjellman alludes, when he says 2 that the trans¬ 
formation in the basal part of U. mirabilis corresponds closely with 
that, which according to Rosenvinge, takes place in Chcetomorpha. 
Var. elongata Rosenv., Gronl. Havalg. (p. 918, fig. 35). This 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^ broad. 
This species occurs on rocks and 
stones near high-water mark, especially on 
exposed coasts where it is washed by the 
waves. R grows gregariously, often asso¬ 
ciated with U. Wormskioldii, Ulothrix flacca, 
Bangia fuscopuiparea, etc. Sometimes 
though rarely, it occurs as an epiphyte on 
larger algae, 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 com¬ 
mon along the coasts of the Faeroes, has hitherto been gathered on 
Str.: Thorshavn, in many places abundantly (!), Kvivig (Lyngb.); Syd.: 
Frodebo (!), Vaagsejde (!); Myggenaes(!); 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 Vsextforhold hos Slaeg'terne Clado- 
phora og Chtetomorpha (Botanisk Tidsskrift, 18. Bind. Kobenliavn 1892). 
2 Kjellman, F. R.: Blastophysa polymorpha ocli Urospora incrassata, tva 
nya Chlorophyceer fran Sveriges vestra kust (Bihang till K. Svenska Vet.-Akad. 
Handlingar. Band 23, Afd. Ill, No 9. Stockholm 1897, p. 13). 
32* 
Fig. 100. Urospora mirabilis Aresch. 
Basal portions of 2 young plants; a 
with extracellular and intracellular rhi- 
zoids; b with intracellular rhizoids 
only. 200 : 1. 
