114 KJELLMAN, THE ALGiE OF THE ARCTIC SEA. 



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. Ag. 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 Rli. lycopodioides 

 on the considerable number of Rh. subfusca from Bohuslän, 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. 



GoBi's 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 betweeu 

 Rh. lycopodioides and Rk. 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 conline myself to stating that, with regard to structure, Rh. subfusca 

 and Rh. lycopodioides are very similar to each other, and diifer essentially from Rh. virgata. 



Remark on the form. As appears from the list of synonyms, I have united in 

 one species all that Rliodomela which has been reported from the Arctic Sea. I 

 liave thus regarded as variations of the same type a great many forms that, at 

 iirst sight and in their extremes, diöer 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 stånd isolated, but are combined with one 

 another by more or less numerous intermediate forms. The two forras 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 marine alga? of Spitz- 

 bergen; ef. Kjellm. Spetsb. Thall. 1. p. 33. Having since that time become acquainted 

 with the form named above f. setacea, which, as is shown by the figures given, stånds 

 undoulitedly 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 oi Rh. lycopodioides, 

 is shown b}' a comparison of figures 1 and 3 on plate 9. 



I formerly regarded Rh. lycopodioides f. tenuissima [i glacialis as a good species, 

 but, having found its subform prrolifera, which merges in Rh. lycopioides f. typica (i 



