242 KJELLMAN, THE ALGE OF THE ARCTIC SEA. 
In my opinion Epmonston’s proceeding is perfectly lawful and consistent, even 
if it should appear that the alga called by him Z. digitata must also be detached as 
a separate species from the collective species LZ. digitata auct. 
That I have referred both ZL. flezicaulis and L. cucullata Fosum to L. digitata is 
caused by my having in the former part of this work, that was printed before I had 
access to Fosrir’s paper, assumed on the authority of Le Joris and J. E. Arnscnoue 
the Laminariew meant by these names to be forms of L. digitata. Accordingly my 
treatment of the alge in question does not by any means imply that I think Fostm’s 
dividing of L. digitata (L. jlexicaulis) into two distinct species is not justified. I have 
thought best to adopt the forms discerned by Fosniz. 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. Clustont and 
other above-named Laminaria of the digitata group. It may be remarked that the 
number and size of the muciferous lacune 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 few 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. 
Habitat. 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 pee 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 Fostin it likes steep slopes and localities where there 
are colonies of Mytilus edulis. It is gregarious and lives on exposed as well as sheltered 
coasts, even in the interior of deep bays. It is certainly known to bear zoosporangia 
during the summer months at Spitzbergen; cp. J. G. Ac. Spetsb. Alg. Till. p. 80 under 
1) It is seen, however, by my description of the form that I have never meant to attribute to it any higher 
degree of independence, as GoBr appears to suppose. Cp. Gonr Algenfl. Weiss. Meer. and KseLim. Kariska 
hafvets Alg. p. 27, Algenv. Murm. Meer. p. 77. 
ee 
