Contribution. I. 139 



f. pannosa (Aresch.) nob. 



Conferva pannosa Aresch. Alg. Scand. exsicc. Ser. 1, Nr. 16. 

 Dcscr. Rhizoclonium pannosum Kutz. Spec. Alg. p. 384. 



Conferva implexa b. Aresch. Phyc. Scand. p. 434; excl. syn. plnr. 

 Fig. Rhizoclonium pannosum Kutz. Tab Phyc. 3, t. 70 I. 

 Exsicc. Conferva pannosa Aresch. 1. c. 



Syn. Conferva obtusangula Lyngb. Hydr. Dan. p. 159. 

 „ „ Sommerf. Suppl. p. 195. 



The typical form of this species forms thin but often 

 extensive strata on rocks, in shallow clefts of rocks, or in 

 the margin of rock-pools, sometimes together with other spe- 

 cies, as Cladophora, Spongomorpha and Rhodochorton Rothii. 

 It is in general less curved and has fewer rhizoid branches 

 than the form figured by Harvey in Phyc. Brit. 1. c, 

 but I have seen specimens which fully correspond with the 

 quoted figure. The form distributed byAreschoug in 

 Alg. Scand. exsicc. Nr. 136 appears to be a transition be- 

 tween /. typica and f. tenuior W i 1 1 r. et N o r d s t. Alg. 

 exsicc. Nr. 625, though most nearly related to the former. 

 The form that I have called /. valida is distinguished from 

 the typical one chiefly by its coarseness and mode of growth. 

 It occurs in narrow and somewath deep clefts of exposed 

 rocks, forming rough, crispate-elevated cushions. The threads 

 differ between 26 and 45 jx in thickness, usually about 

 30 p.. A form very unlike the latter in habit but other- 

 wise nearly related to it is the above mentioned /. pannosa 

 It grows on posts or other woodwork, or sometimes on 

 rocks, and forms rather thick and dense layers with a un- 

 dulate-lacunosed surface. In coarseness and the length of 

 the cells it corresponds with f valida, but the rhizoid bran- 

 ches are numerous and longer than by the latter. 



The present plant lives in the upper part of the lito- 

 ral zone, sometimes even a little above high- water mark, on 

 open coasts as well as sheltered ones. Specimens witji 300- 



