Jan. 1895.] BOTANICAL SOCIETY OF EDINBURGH. 343 



2. Codiolum j^ysillum (Lyngb.), Fosl. {non Kjellm. Alg. 

 Arct. Sea). — In shallow pools between tide marks, at a 

 high level, near the " Natural Bridge," in abundance ; also 

 at Scarvigjo. 



This Codiolum, after a careful examination, by Messrs. 

 Batters and Foslie, has been referred to C. piisillum 

 (Lyngb.), Fosl. The so-called species of Codiolum, how- 

 ever, run into each other in a very puzzling manner. 

 They differ chiefly in measurements, and — as Mr. Batters 

 remarks — measurements are somewhat uncertain tests, 

 especially if taken, as in the present case, from barren 

 plants. 



Mr. Foslie writes to me as follows : — " In my opinion 

 your Codiolum is most nearly related to C. pusillum 

 (Lyngb.), Fosl. {no)i Kjellra. Alg. Arct. Sea). It differs 

 from C. grcgarium, according to A. Braun's description in 

 ' Alg. Unicell.,' in that the stipe most often passes into the 

 club without any limit, and the latter thinner in propor- 

 tion to the length than in G. gregarmm. It is slightly 

 larger than the form of C. piisillum collected by Lyngbye 

 at the Faroe Islands, and agrees better with the form of 

 that species found in Finmarken, and recorded by me in 

 ' Contrib.' I., p. 151, and not identical with the species 

 mentioned by Kjellman under the same name in ' Alg. 

 Arct. Sea,' which I have called C. ajlindraceum. These 

 two species are certainly nearly related, but cannot in my 

 opinion (and Kjellman's) be considered as forms of G. 

 gregarium." 



Professor Kjellman, in "Alg. Arct. Sea," p. 319, writes: 

 — " The genus Codiolum has shown itself of late to possess, 

 in the northern seas, a considerable number of forms that 

 are only slightly differentiated, and should possibly be 

 justly regarded as forms of one and the same species. 

 It is evidently a genus in the course of developing species. 

 Nevertheless, the species distinguished ought to be kept up 

 until more forms shall have been discovered at other 

 places. This will, no doubt, happen now, since more 

 attention has been directed to these small and easily over- 

 looked Al^ae." 



3. Hydrocoleum lynghyaceum, Ktitz., forma rupestris, 

 Kiitz. — At Xoustar, in shaded crevices, at a high level. 



