— 178 - 



nearly to the base. The stipe is 5 — 26 cm. long, the lamina 40— 110 cm. 

 long and 14 — 40 cm. broad. The occurrence of the muciparous canals 

 in the stipe is somewhat varying. The muciparous canals form usually 

 a dense circle, but sometimes there are only to be seen some few of 

 rather great size. Not rarely the stipe is destitute of muciparous canals 

 especially in smaller specimens. 



The original specimens of Laminaria discolor Strömf. agree fully 

 with my own, and the Greenlandic specimens of Laminaria nigripes 

 ß atrofulva. Strömfeit however says in the description of Laminaria 

 discolor that the stipe is destitute of muciparous canals, but in some 

 of his original specimens I have found fairly developed muciparous canals 

 in the stipe. The Laminaria discolor must consequently be regarded as 

 fully identic with Laminaria nigripes /?, atrofulva. 



Laminaria nigripes J. Ag. f. oblonga Kjellm. (Arct. Alg. p. 237) is 

 reported by Stromfelt (1. c.) with some doubt, as the specimen he picked 

 up from a depth of 8 fathoms was destitute of the stipe. As far as I 

 can see from the description of f. oblonga Kjellm. (1. c.) it must belong- 

 to Laminaria nigripes ß, atrofulva. 



This species belongs to the sublitoral region, and is found down to 

 a depth of 10 fathoms, but it is also found in rock-pools in the lower 

 part of the litoral region. It has only been found in E. Iceland, where 

 it seems to be rather common. 



E. Icel. Berufjöröur, Reyöarfjöröur, SeyöisfjörÖur. 



Laminaria digitata (L.) Lam., Kjellm. Arct. Alg. p. 240, Handbok 

 p. 22 ; Strömf. Algveg. p. 45. 



This species is extremely common along the coasts of Iceland and 

 in company with L. saccharina, L. hyperborea, Alaria esculenta and Alaria 

 Pylaii it forms the common Laminaria-zone (see under L. saccharina). It 

 is also met with in pools in the lower litoral region. 



The species is highly variable. The variations, I think, are due to 

 environmental influences, and the most determining factors I see in the 

 degree of depth and in the force of movement in the water. Three 

 extreme forms, easily recognizable are to be found along the Icelandic 

 coasts. In the Laminaria-zone we meet the main form usually consisting 

 of great specimens, the lamina of which is proportionally broad and split 

 into segments of varying breadth. At low-water mark in much exposed 

 places we find the form with more leathery, proportionally long and 

 narrow lamina, split nearly to the base in some few and narrow segments. 

 The third form, on the other hand, is to be found in sheltered places at 

 the inner end of fjords in some depth. The lamina of this form is propor- 

 tionally very broad, often cucullate, undivided or split into two or few 



