114 KJELLMAN, THE ALG OF THE ARCTIC SBA. 
or sickle-shaped, erect ramuli, which are thickest a little below the middle and at- 
tenuated towards the base. They occur without any apparent order, sometimes very 
numerous, sometimes very few, and are, as far as I have been able to see, a sort 
of adventive branches. A good figure is to be found in J. G. Aa. Spetsb. Alg. Bidr., 
pl. 2, fig. 2. In Rhodomela subfusca there are certainly branches, that remind one of these, 
viz. those above indicated as elements 1 of the ramification, but these are subulate or 
cylindrically subulate, issuing from broad bases and always developed in strictly acro- 
petal order. I have never seen any formations resembling those of Rh. lycopodioides 
on the considerable number of Lh. subfusca from Bohuslin, that I have examined. 
These circumstances seem to me to imply, that Rh. lycopodioides and Rh. subfusca are 
two distinct, although feebly differentiated species, which have possibly once sprung 
from one type, but afterwards developed differently. 
Goxrs opinion that different species should be perceptibly unlike in anatomical 
structure can scarcely be regarded as defensible. If such a condition should be car- 
ried out in algology, a considerable number of species, constant, easily recognizable, 
and regarded as good, must be suppressed and subsumed under others in long series. 
External morphological diversity ought certainly even here to be considered valid as a 
character of species. Small anatomical diversities are indeed to be found even between 
Rh. lycopodioides and Rh. subfusca, but the anatomical structure of both species being 
essentially different in different, older or younger, portions of the frond, and the diffe- 
rent forms of what is undoubtedly Rh. lycopodioides being also somewhat different from 
one another in this respect, it is necessary to examine a great many specimens of 
different ages and places of growth, in order to be able to ascertain what is essential or 
unessential. I have not had an opportunity to undertake such an examination, and I am 
thus obliged to confine myself to stating that, with regard to structure, Rh. subfusca 
and Rh. lycopodioides are very similar to each other, and differ essentially from Lh. virgata. 
Remark on the form. As appears from the list of synonyms, I have united in 
one species all that Rhodomela which has been reported from the Arctic Sea. I 
have thus regarded as variations of the same type a great many forms that, at 
first sight and in their extremes, differ most considerably from the typical form. 
As far as I can judge, there is ta present no other course left. The principal 
forms, that I have tried to discern, do not stand isolated, but are combined with one 
another by more or less numerous intermediate forms. The two forms which I have 
called f. flagellaris and f. tenuissima (? glacialis are those most unlike the typical one. 
To the former one of these I have not before been able to assign a place, but have 
mentioned it as an alga incertw sedis in my description of the marme algw of Spitz- 
bergen; ef. Ksenim. Spetsb. Thall. |. p. 33. Having since that time become acquainted 
with the form named above f. setacea, which, as is shown by the figures given, stands 
undoubtedly near f. flagellaris, I do not hesitate to regard it as a peculiarly deve- 
loped Rh. lycopodioides. That f. setacea belongs to the series of forms of Kh. lycopodioides, 
is shown by a comparison of figures 1 and 3 on plate 9. 
I formerly regarded Rh. lycopodioides f. tenuissima ( glacialis as a good species, 
but, having found its subform prolifera, which merges in Rh. lycopioides f. typica B 
