MARINE ALGAL VEGETATION 171 



Sweden (Kyi in, 45) the hairs are cast in June, but (young) hair- 

 hearing individuals may, however, be met with in July. 



Polysiphonia urceolata has hair-leaves in the spring, summer 

 and beginning of autumn, but individuals without hairs are found 

 side by side with hair-bearing ones from May to August. In De- 

 cember only hairless individuals have been observed at Reykjavik, 

 and in January February only hairless plants have been collected 

 in N. Iceland. 



Rhodomela lycopodioides has been collected with hair-leaves in 

 March July, and hairless in June August in SW. Iceland; with 

 hair-leaves in April December, and hairless in July August in N. 

 Iceland; with hair leaves in June July and hairless in May July 

 in E. Iceland. In the autumn this species had cast off its leaves 

 and branches in SW. Iceland. 



In addition to this, the following instances of the occurrence 

 of young shoots may be mentioned: 



Odonthalia dentata. The young shoots in this species are readily 

 recognized by their paler red colour. Material from January- 

 February bears young shoots. The latter are easily recognizable in 

 January, and have probably begun to grow out in December. The 

 young shoots then increase in size, and the colour becomes gradu- 

 ally darker month by month. In material collected in June July 

 the length of the year's shoot may even then be determined in 

 some of the individuals, but I believe, however, that it is in July 

 that the shoot is almost full-grown. 



Polysiphonia fastigiata has young shoots in December at Reykjavik. 



Odonthalia shows distinctly the period of development of the 

 vegetative shoots in the sublittoral zone, and I presume it may be 

 taken for granted that the other sublittoral species do not differ 

 very much from it as regards this point. 



In Greenland the formation of the new shoots begins in Feb- 

 ruaryMarch (Rosenvinge, 63, p. 239), and the growth is con- 

 tinued until August or during the whole summer. 



In the Faeroes the new shoots begin to appear in the latter part 

 of autumn (Borgesen, 12, p. 828). 



From Spilzbergen (Kj ell man, 36) some sublittoral species are 

 known which form new shoots during the winter, as for instance, 

 Delesseria sinuosa in January, and Rhodymenia palmata from No- 

 vember to May. 



