110 L. KoLDERUP Rosenvinge. 



certainly been lying loose on the bottom; in some of them the 



undermost part is in a state of disintegration. For most of the 



specimens from the harbour it has also been stated, that they have 



been dredged on soft bottom. Some smaller specimens are however 



provided with basal disc. 



Log. Along Ivoldewey Island, 15 meters and deeper; Danmarks Havn, 

 7—11 meters, soft bottom. 



Actinococcus Kiitz. 



19. A. subcutaneus (Lyngb.) K. Rosenv. 



K. Rosenvinge (1893) p. 822. (1898 I) p. 33; Jonsson (1904) p. 14. 



A large specimen of Phyllophora Brodicei * interrupta bears nu- 

 merous specimens of this much disputed alga attached to the upper 

 margin of some of the one-j^ear old segments. 



I^oc. Along Koldewey Island, ca. 15 meters. 



Ceratocolax K. Rosenv, 



20. C.Hartzii K. Rosenv. 



K. Rosenvinge (1898 Is p. 34. 



Several specimens of Phyllophora Brodiœi "interrupta are infested 

 with this parasite which is situated partly on the border partly on 

 the flat side of the frond. The specimens of the parasite form small 

 bushes up to 3 mm. in diameter, fully agreeing with the previously 

 found Greenlandic specimens; several of them bore nemathecia, but 

 the sporangia Avere still undivided in August. The specimens of 

 Phyllophora on which they were parasitic were certainly all loose- 

 lying when dredged. 



Loc. Danmarks Havn, 7—11 meters, August. 



Choreocolax sp.? 



In a specimen of Eiithora cristata from Koldewey Island were 

 found some cushions of a small parasitic Floridea looking much 

 like a Choreocolax or Harveyella. As there is not sufficient material 

 for a detailed description, I shall not mention it closer but only 

 state that it grows in the same manner as Harveyella and Choreocolax, 

 sending out from the underside of the cushion-shaped or nearly 

 globular frond filaments penetrating between the cells of the host. 

 In a dried state the parasite has a pretty red colour. 



Fam. Helminthocladiaceœ. 

 Chautransia (D. C.) 



21. Ch. efflorescens (J. Ag.) Kjellm. 



K. Rosenvinge (1898 I) p. 40, (1909) p. 134. 



