- Ill — 



also comes in consideration with regard to the interpretation of 

 C. arcticum. These cells however are more frequent in the above- 

 named forms of C. Are- 

 scJiougii than here. I have 

 not observed any organs 

 of fructification. The co- 

 lour is in the dry condi- 

 tion of the specimens black 

 with feeble reddish tint; 

 when steeped in water it p ig IV 



beCOmeS deep-red mUCh C. septentrionale; lower margin of an older zone. Charac- 

 ^ 7 ter towards C. fruticulosum. x c. 380. 



as in C. rubrum. 



This species was found in West-Greenland at Godhavn ( 26 li 

 1886, Kolderup Rosenvinge) and in an unknown locality (H. P. 

 Sørensen), probably in the waters near Disco. 



Ceram. circinnatum Ag. ? Fig. V, 1. 



According to J. G. Agardh (Anal, algol. Gont. II, p. 30) this species 

 is the only representative in the group of Ceramium in which the 

 zones particularly are growing downwards. Certainly this group and 

 the limits of C. circinnatum are not very obvious. Probably more 

 species are included here of which one must be named C. (Recur- 

 rens. As the matter stands it might be correctest for the present 

 to refer every form with particularly downwards growing zones to 

 this species. And thus I do it now, referring 3 specimens, though 

 somewhat different, to C. circinnatum. 



These 3 specimens were collected by H. Jonsson : in SW. Iceland 

 in Skerjafjordur, 10 /t 1905 (2 spec.) and at Stykkisholmur, 16 /e 1897, 

 in the upper littoral zone and in sheltered localities. The speci- 

 mens from Skerjafjordur are more dichotomous and slender than 

 that from Stykkisholmur; on the other hand this latter is furnished 

 with more rubroid bark, but as to the degree of the development 

 of this, all 3 specimens seem to agree. 



Near the apices, which in all specimens are very thin with 

 distinct forcipes, the bark consists of sharply confined zones with 

 narrow interstices. Somewhat downwards the zones begin to be 

 different in the margins, the upper not growing while the lower is 

 beginning the growth downwards in distinct rows. The upper 

 margin lies in this stage near the diaphragmata between the axial- 

 cells. Later on the zones are confluent from both margins. 



In the specimens from Skerjafjordur a great number of zones in 



