KONGL. SV. VET. AKADEMIENS HANDLINGAK. BAND. 20. N:0 5. 225 



låter more numerous, sometimes so numerous as to constitute the greater mäss of the 

 central part of the stipe. By their very thick walls they contrast strongly with the 

 adjoining cells; (tab. 25, fig. 1 — 4). '^ 



In general this is the structure of the stipe also in Ph. lorea; but in transverse 

 sections of the stipe both in younger and older individuals the above-mentioned tubular 

 cells are not visible. On closer examination they are certainly detected and are found 

 to occupy the same position as in the preceding species, but their walls are ahvays 

 thin, not differing in thickness from the walls of the adjoining parenchymous cells 

 (tab. 25, fig. 5). With regard to the cryptostomata the species Ph. dermatodea varies 

 coTisiderably. They are sometimes pretty numerous in older individuals, csarce in 

 younger ones, sometimes very rare or almost absent both in younger and older spe- 

 cimens. The former is usually the case in specimens from the north coast of Norway, 

 the latter in specimens from other parts of the Arctic Sea. The shape and structure 

 of the cryptostomata is accurately described by J. E. Areschoug Obs. Phyc. 3, p. 12. 



Habitat. In the Arctic Sea proper the present species occurs in company with 

 other Laminariaceee and is usually met with here at a depth of 2 — 10 fathoms on rocky 

 or stony bottom. On the coast of Norway it does not belong to the proper formation 

 of Lammariacece, but descends deeper than this, even to a depth of 20 fathoms. But 

 it is most common here in shallow, rather exposed bays on gravelly bottom in 4 — 5 

 fathoms. On the north coast of Spitzbergen young individuals were common in the 

 winter, rior were older ones wanting during the same season. Of the other species, 

 Ph. lorea, on the contrary, young specimens were most common during the summer. 

 On the coast of Norway younger and older specimens are of rather the same frequency 

 during the summer-months, in Jnly and August. At Spitzbergen I have found speci- 

 mens with zoosporangia in July and August, at Novaya Zeralya in July, on the north 

 coast of Norway in the latter part of August and at the beginning of September. 

 However, the proper season for the formation of the zoospores on the last-named coast 

 ' appears to come someAvhat låter, towards September or the beginning of October. 



Geogr. Distrib. It is known from those parts of the Polar Sea which extend 

 northw^ards of the Atlantic. Its maximum of freqnency seems to be on the north coast 

 of Norway, aithough even here it does not occur in such numbers as are comparable 

 in any way with other Laminariaceee. 



Localities: The Nonoegian Polar Sea: Finmarken at Maasö, Gjesvaar, the south 

 coast of Magerö, Öxfjord and Talvik, usually local and rather scarce; at Maasö pretty 

 abundant. 



The Greenland Sea: Beeren Eiland; on the north and west coasts of Spitzbergen 

 local and scarce. 



The White Sea: According to GoBi it is probably this species which K. v. Baer 

 has taken at Tri-Ostrowa. 



-Bafjin Bay: the west coast of Greenland at Claushavn. 



With regard to the distribution of the two forms I can only say that the Phyllaria. 

 dermatodea which I found on the north coast of Norway belongs to f. typica, but that 

 from the Greenland Sea and the Murman Sea to f. arctica. 



29 



K. Vet. Akad. Handl. Bd. 20. N:o 5. 



