On the Marine Algæ from North-East Greenland. Щ 



Found in small quantity on Delesseria simiosa and Cnioria arc- 



tica. The thickness of the filaments is 5— 6/^. Antheridia, carpo- 



gonia and ripe cystocarpia occurred in August. 



Loc. Along Koldewey Island; Danmarks Havn and the entrance to the 

 harbour. 



Fam. Bangiaceœ. 

 Coiichocelis Batt. 

 22. С rosea Batters. 



Batters (18;»2 p. 25; K. Kosenvinge (1898 I) p. 44. 



Non Ostreobiiim Qiieketti Born, et Flah. var. rosea Nadson (1!)0Ü) p. 3(i. 



This perforating alga is frequently met with in old shells in 

 particular of Mija and Saxicava, which assume a rose-red colour 

 when the alga occurs alone or is predominant. It agrees very well 

 with Batters' description and figures. According to Nadson (1. c.) 

 this alga should not be a Rhodophycea but a red variety of Ostreo- 

 biiim Qiieketti; this however does not agree with my observations of 

 the material from North-East Greenland. Conchocelis and Ostreobiiim 

 grow frequently intermingled in these shells, but they are very easy 

 to distinguish and do not show any indication of mutual transition. 

 Conchocelis is always rose-coloured, while Ostreobiiim is constantly 

 green. Conchocelis consists always of articulated filaments, the cells 

 of Avhich are more or less inflated in the middle but narrow at the 

 transverse walls, while the filaments of Ostreobiiim are continuous 

 and show here and there large irregular inflations. As far as I 

 know, Nadson has given no account of the manner in which the 

 transition takes place betAveen these two widely diflerent algæ\ and 

 it seems therefore most probable, that the red alga which Nadson 

 examined is not the true Conchocelis rosea but rather a red variety 

 of Ostreobium Queketti. 



As stated bj^ Batters, the alga forms within the surface of the 

 shell a horizontal layer of interlaced filaments of very various shapes 

 and w^idths. The cells are often inflated in the middle and the fila- 

 ments may then be more or less moniliform. I have not been able 

 to detect au}^ pore in the middle of the transverse walls. In the 

 deeper parts of the shell some filaments are thicker, consisting of 

 short cylindric cells separated by broader transverse walls and with 

 rich plasmatic contents (comp. Batters I.e. pi. VIII figs. 2- 6). In the 

 thinner cells I have found a parietal chromatophore which seems 

 to be much branched; in some cases I saw however several intensely 

 red-coloured bodies in each cell, probably chromatoi)hores. In some 



' Mag. O. Paulsen has most kindh' translated for me the part of Nadson's Russian 

 text treating of Conchocelis. 



