242 KJELLMAN, THE ALG^ OF THE ARCTIC SEA. 



In my opinion Edmonston's proceeding is perfectly lawful and consistent, even 

 if it shonld appear that the alga called by him L. digitala must also be detached as 

 a separata species from the collective species L. digitata au et. 



That I have referred both L. flexicaulis and L. cucidlata Foslie to L. digitata is 

 caused by my having in the former part of this work, that was printed before I had 

 access to Foslie's paper, assumed on the authority of Le Jolis and J. E. Areschoug 

 the Laminariai meant by these names to be forms of L. digitata. Accordingly my 

 treatment of the algse in question does not by any means imply that I think Foslie's 

 dividing of L. digitata (L. flexicaulis) into two distinct species is not justified. I ha,ve 

 thought best to adopt the forms discerned by Foslie. But it appears to me doubtful 

 whether f. valida is really a proper variety and not only a condition of f. genuina of 

 a different age. However, it is possible that this is not the case. 



That form of L. digitata which I have described under the name of f. complanata 

 seems to deserve to be specially mentioned quite as well as the others. Older larger 

 individuals, by their very broad stipe that is much flattened upwards, assume an aspect 

 very different from other forms ^). 



As mentioned before, the present species is plainly distinct from L. Clustoni and 

 other above-naraed Laminarice of the digitata group. It may be remarked that the 

 number and size of the muciferous lacuna3 are subject to rather considerable variations. 

 In general they are smaller and fewer in individuals from higher than from lower 

 latitudes. In specimens from Spitzbergen they are sometimes exceedingly fcAv and very 

 difficult to distinguish from the adjoining cells, in specimens from the north coast of 

 Norway, on the contrary, they are not seldom very numerous and sometimes very large 

 in proportion to the size of the cells in the intermediate layer. They are then situate 

 sometimes nearer to the cortical layer, sometimes farther inwards in the intermediate 

 layer, and in the latter case they are often in a great part of their periphery surrounded 

 with cells differing in size and shape from the other cells in the intermediate layer of 

 the lamina. 



Hahitat. This species is usually sublitoral in the Polar Sea, but on the north coast 

 of Norway it even ascends into the litoral zone, living then in rock-pools. However, 

 it is to be found more abundant and fully developed only at or immediately below 

 low-water mark and from this line it descends down to a depth of ten fathoms. But 

 the greatest and densest masses are met with in the upper part of the sublitoral zone. 

 In the Arctic Sea proper it belongs to the middle and lower part of the sublitoral 

 zone, never rising here to low-water mark. 



It is most vigorously developed on a bottom of solid rock, but occurs also on 

 gravelly ground. According to Foslie it likes steep slopes and localities where there 

 are colonies of Mytilus edidis. It is gregarious and lives on exposed as well as sheltered 

 coasts, even in the interiör of deep bays. It is certainly known to bear zoosporangia 

 during the summer months at Spitzbergen; cp. J. G. Ag. Spetsb. Alg. Till. p. 30 under 



') [t is seen, however, by my dcscription of the form that I have never meant to attribute to it any higher 

 degree of imlependcnce, as GoBi appears to snppose. Cp. Gobi Algenfi. Weiss. Meer. and Kjellm. Xariska 

 iiafvets Alg. p. 27, Algcnv. Mnrm. Meer. p. 77. 



