Oll the Marine Algæ from North-East Greenland. 



107 



луеге slerile. Specimens found frozen in the ice in April bore tetra- 

 sporangia in the shoots of the previous year. 



Loc. Along Koldewey Island; in clumps frozen in the ice at Cap Amelie. 



Polysiphonia Grev. 

 13. P. arctica J. Ag. 



K. Rosenvinge (1893) p. 800, (1898 I) 

 p. 25; Jonsson (1904 , p. 10. 



Non Pterosiphoiiia arctica Setciiell 

 and Gardner (1903) p. 3'i9. 



A considerable number of 

 specimens of this strongly arctic 

 species has been collected in two 

 localities situated comparatively 

 near the open sea; they fully 

 agree with typical specimens, 

 reaching a length of over 20 cm. 

 and are as usual without basal 

 part. They seem not to have 

 been fixed to the bottom and are 

 all sterile. 



Pterosiphonia arctica Setchell 

 and Gardner (1. c.) which these 

 authors have thought identical 

 with Polysiphonia arctica, after 

 comparison with a specimen from 

 Greenland determined by me, is 

 fairh' distinct from it, judging 

 from the remarks and the figures 

 of the authors. The Northw^est 

 American species has a compla- 

 nated frond, is plainly distichous 

 near the tips and has constantly 

 6 or 7 pericentral cells, while 

 Polysiphonia arctica has a cylin- 

 drical frond \vith branches given 

 off on all sides and 4—7 pericen- 

 tral cells. As no figures of this 

 species have ever been published, 



I give here some drawings, showing the ramification and transverse 

 sections of the frond (fig. 4). The branches are spirally arranged 

 with an angle of divergence approaching to 180°, however somewhat 

 smaller. As shown before (1893, p. 800) no hairs (trichoblasts) 



XLUI. 9 



Fig. 4. Polysiphonia arctica. A, Upper end 



of a plant ; at p formation of the secon 



dary pores. BD, transverse sections of 



fronds. 200 ; 1. 



