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F. Børgesen : Rhodophyceæ of the Danish W. Indies. 241 



Subtam. /. Ceramieæ, ) mew york 

 Centroceras Kützine;. botanical 



ÜAKüCN 

 1. Centroceras clavulatum (Ag.) Mont. 



Montagne, C, Exploration scientifique de l'Algérie, Algues, Tome I, 

 1846, p. 140. J. Agardh, Spec. Alg., p. 148; Epicrisis, p. 108. Harvey, Nereis, 

 Bor. -Am., Part II, p. 211, tab. 3.3 C. 



Centroceras clavulatum Ag. in Kunth, Synopsis Plantarum, vol. II, 1822, 

 p. 2. 



Of this specie.?, which is very common in the West-Indian 

 seas, a series of specimens has been examined, frequently differing 

 from each other, but, so far as we can judge, the variations in 

 question are only modifications due to different localities. Most 

 of the specimens are sterile ; tetrasporangia have been found now 

 and then, but no cystocarps. 



Centroceras clavulatum is fixed to the substratum by means 

 of rhizoids. These have a shorter or longer pluricellular stalk, 

 ending in an irregularly lobed disc. 



This species is found in very varying localities, from the 

 most exposed to quite sheltered. Thus it is common in the calm 

 water of the lagoons, fixed to the roots of the mangroves. And 

 on the other hand it is found upon the rocky shore of the north 

 west end of St. Croix, where it is constantly washed by the 

 waves. 



It seems to occur in shallow water only. In deep water it 

 has never been met with. 



It is very common along the shores of the islands. 

 Geogr. Distrib.: Seems to occur in all warmer seas. 



Ceramium Lyngbye. 



1. Ceramium fastigiatum (Roth) Harv. 



Harvey, W. H., Remarks on some British Algæ in Hooker, Journal 

 of Botany, vol. V, 1834, p. 303. J. Agardh, Spec. Alg., vol. II, p. 119. 

 Conferva fastigiata Roth. Catalecta botanica, II, 1800, p. 175. 



f. flaccida H. E. P. n. f. 



Ceramium fastigiatum w^as originally described by Roth, later 

 •on adopted by Harvey, supported by Mrs. Griffiths, but with 



^) Dr. Henning E. Petersen has most kindly determined my material 

 of the Ceramieæ and the systematic notes are due to his thorough 

 knowledge of this group. 



Dansk Botanisk Arkiv, Bd. 3. Nr. 1 (1918). 16 



