KONGL. SV. VET. AKADEMIENS HANDLING AR. BAND. 20. N:0 5. 213 



have come from more northern localities, are distinctly marked with the characteristics 

 set down by J. G. Agardh for A. muscefolia. Some of them might very well have 

 served as original for De la Pylaie's figure of Laminaria esculenta var. platyphylla, 

 which is regarded by J. G. Agardh as the typical A. muscefolia. Between these two 

 plants, A. esculenta and A. muscefolia as understood in this sense, no fixed limits can 

 be drawn. The one, A. muscefolia, is a northern form, the other, A. esculenta, a southern 

 form of the same speciesi I have been able to lay out a complete series of transitions 

 between them. 



In order to show what the dimensions of this beautiful species are in our seas, I 

 shall give the measures of the largest specimens at my disposal. The stipe is 15 cm. 

 long, one cm. in diameter downwards; the rhachis has a length of 5 cm., the naked costa 

 above the rhachis a length of 2 cm.; the lamina is one metre and a half long and 12 cm. 

 broad at its broadest part, which is situate 35 cm. above the base of the lamina. The 

 leaves are 12 cm. in length and 1 cm. in breadth. That Fucus pinnatus Gunn. belongs 

 to this species, seems to me very dubious. I believe it is to be identified with Alaria 

 Pylaii J. G. Ag. I shall return to this question in my account of the last-mentioned 

 species. 



Habitat. The present species lives gregarious at low-water mark or somewhat below 

 that line in the uppermost part of the sublitoral zone, principally on solid rocks in 

 exposed localities. It is found still flourishing at the end of August, but its highest 

 development seems to be attained during the earliei' part of the summer. On the arctic 

 coast of Norway I have found individuals with mature zoosporangia in July. 



Geoqr. Distrib. Undoubtedly it reaches its maximum of frequency in the southern 

 part of the Norwegian Polar Sea; at Finmarken it is scarce, being replaced here by 

 A. membranacea. It is also reported from the Greenland Sea by J. G. Agardh, but I 

 have failed to detect it here myself. 



Localities: The Norwegian Polar Sea: Nordlanden common; Finmarken: Maaso 

 local and scarce. 



The Greenland Sea: the coast of Spitzbergen according to Agardh. 



Alaria Pylaii (De la Pyl.) J. G. Ag. 



Gronl. Lam. och Fuc. p. 24. Laminaria Pylaii De la Pyl. F1. Terre neuve p. 29. 

 Descr. Alaria Pylaii J. G. Ag. 1. c. 



Syn. Alaria Despreauxii J. G. Ag. Gronl. Alg. p. 110. 



» esculenta Kleen, Nordl. Alg. p. 32; ex parte, fide syn. 

 » Pylaii Ceoall, PI. Disc. p. 457. 

 Fucus pinnatus Gunn. F1. Norv. 1, p. 96 (?). Acta Nidros. t. 8, fig. 1(?). 



Remark on the species. Besides Alaria esculenta as I have understood above, there is 

 to be found on the north and west coasts of Norway at least northward from Aalesund 

 another Alaria which is certainly specifically distinct from the former. I possess a con- 

 siderable number of specimens of it, both young ones bearing their first sporophylla 

 and older ones with scars of fallen leaves. They are easily distinguished from speci- 



