35 



170 



H. JONSSON 



lamina takes place in February— March. In April individuals with 

 large, new laminae, with the old laminae or portions of them still 

 attached, are frequently found at Reykjavik, but the majority of the 

 Laminaria individuals have renewed their laminae by that time. A 

 few individuals are however met with until June in SW. Iceland in 

 the act of lamina-renewal. With regard to some of the most common 

 species the following may be noted: — 



Laminaria saccharina in SW. Iceland (1897) was frequently found 

 in the lamina-renewal stage in April, while some individuals were 

 renewing their laminae in May. Laminaria digitata: some individuals 

 were renewing their laminae in April and until June in SW. Iceland 

 (1897). Laminaria hyperborea in SW. Iceland (1897), some were re- 

 newing their laminae in May — June. 



L. hyperborea was found renewing its laminae in July on the 

 north coast of Iceland. This was observed only once, therefore it 

 cannot be concluded from this that the lamina-renewal stage com- 

 mences later or lasts longer on the north coast than in SW. Iceland. 



In the Faeroes (Borgesen, 11 and 12) the lamina-renewal stage 

 occurs at the same time as in SW. Iceland. 



On the west coast of Sweden the renewal of the lamina takes 

 place during winter (Kylin, 45) and in Laminaria saccharina and 

 L. digitata the young leaf, in December, is a quarter the size of the 

 old one; in April it is only exceptionally that individuals are found 

 with a portion of the old lamina attached. The renewal of the lamina 

 in L. hyperborea takes place later, and in April the new lamina is a 

 quarter the size of the old one, and in the beginning of July a 

 portion of the old lamina is still present. 



In connection with the lamina-casting species the following may 

 be mentioned : — 



Desmarestia aculeata has been collected bearing the brown, as- 

 similatory hairs in March — May in SW. Iceland, in May in NW. 

 Iceland, in June in E. Iceland, and in July in N. Iceland. This 

 appears to indicate that the hair-bearing stage occurs later on the 

 north and east coasts, or that it lasts longer. The species behaves 

 in the same manner in Greenland (Rosenvinge, 61, p. 857) where 

 the hairs are cast off, at the latest, in June in South Greenland, 

 while hair-bearing individuals are found in July and August in 

 North Greenland. In the Faeroes it has been observed with hairs 

 upon it in May — June (Borgesen, 13, p. 445), but hair-bearing 

 individuals were, however, rare in June. On the west coast of 



