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



321 



the filaments taper evenly upwards their ultimate summits reaching 

 only a breadth of 8 |i. The cells are often more than 200 \x long. The 

 summits of the filaments are obtuse. The ramuli are repeatedly 

 pseudodichotomously ramified; the monosiphonous branches issue 

 with acute angles. The whole ramuli are upwards directed and at 

 the summit of the branches and branchlets somewhat incurved. 



The specimens examined were all sterile. 



The Acrochæti- 

 um opetigenum, oc- 

 curring upon Dasya 

 elegans and describ- 

 ed on p. 38 of the 

 present volume, was 

 very common, too, 

 on this species (vide 

 Fig. 323 a, two young 

 specimens are seen). 



This plants re- 

 minds one as to its 

 whole appearance 

 and ramification ra- 

 ther much of Dasya 

 ramosissima, but it 

 differs greatly from this species by its much longer ana slender 

 ramuli with longer cells and obtuse summits. 



The large basal cell is not so markedly developed in Dasya 

 ramosissima, and the cortical layer is less and differently, too, devel- 

 oped in this species. Also the rosy -red colour of our plant differs 

 from the more brownish of Dasya ramosissima. 



Also with Dasya Harveyi our plant may be compared ; but this 

 has, according to Falkenberg, p. 625, four pericentral cells, its 

 ramuli are slender and are not ocellate at the summits of the branches. 



Fig. 324. Dasya spec, a, part of the thallus with a 



ramulus. b, base of a ramulus more magnified (nearly 



the same enlargement as that of Fig. 323a). 



(a, about 30:1, b, 65:1). 



I want yet to mention a form here (my coll. no. 1790) of which 

 only a single plant was found. This had nearly the same rosy-red 

 colour and whole habitus as the above-mentioned form with excep- 

 tion of the ramuli which were much more robust (Fig. 324): at their 

 base the cells were 31 |i thick, somewhat higher up their diameter 

 increased to about 60 \x, the following cells tapering gradually up- 



Dansk Botanisk Arkiv, Bd. 3, Nr. 1 (1919), 



21 



