I 



F. Børgesen : Rhodophyceæ of the Danish W. Indies. 7 



Subfam. 2. Erythrotrichieæ. 

 Erythrotrichia Areschoug. 



1. Erythrotrichia cariiea (Dillw.) J. Ag. 



J. Agardh, Till Algernes Systematik, VI, Ulvaceæ (Lunds Univ. Års- 

 skrift, t. XIX, 1883, p. 15. Rosenvinge, Mar. Algæ of Denmark, part I, 

 1909, p. 67. 



Conferva carnea Dillwyn, British Conferv., 1809, pi. 84. 



Conferva ceramicola Lyngb., Hydrophytol. 1819, p. 144, pi. 48 D. 



Bangia ceramicola Chauvin, Recherches sur l'org. . . . d'Algues, Gåen 

 1842, pag. 29—30; Harvey, Phycol. Brit., pi. 317. 



Erythrotrichia ceramicola Aresch., Phyc. Scandinav. 1850, p. 210; Le 

 JoLis, Alg. mar. Cherb., 1880, p. 103, pi. 3, fig. 1 — 2; Berthold, Bangia- 

 ceæ, 1882, p. 25. 



The plant is, as mentioned and figured by Rosenvinge, 

 fastened to the substratum by the basal cell which forms an irre- 

 gularly lobed disc often with ramified rhizines radiating from it. 



The length of the vegetative cells is rather variable ; most 

 often the length is shorter than the breadth, but cells longer than 

 broad occur. The cells contain a starlike chromatophore with a 

 large pyrenoid and a small nucleus not always easy to find as it 

 is often, as pointed out by Rosenvinge, hidden behind the 

 chromatophore. 



The reproductive cells are commonly somewhat longer than 

 the breadth, the sporangium was of about the same size as the 

 sister cell or somewhat smaller. 



It has been gathered in the months December — March and 

 was in fruit it that time. 



It occurs epiphytically upon larger algæ, e. g. Sargassum, 

 Acanthophora etc. and seems to be rather common. 



Geogr. Distrib. Atlantic coast of Europe and North America, Medi- 

 terranean Sea, Maroc, West coast of North America etc. 



Erythrocladia Eosenv. 



1. Erythrocladia subintegra Rosenv. 



Rosenvinge, L. Kolderup, The marine Algæ of Denmark, Part I, 

 København 1909, p. 73. 



This plant was found epiphytic (Fig. 3 d) ^) upon specimens 

 of Chætomorpha and Cladophora upon which it forms small roundish 



^) In contradiction to the statement of Rosenvinge, Howe (in "The 

 marine Algæ of Peru", p. 82) is of the opinion that it is ordinarily 

 immersed in the wall of the host and that it is "endophytic rather 

 than epiphytic". 



