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



335 



of the filaments. A branchlet is given off from each segment so, that 

 they are placed alternately on both sides of the median hne of the 

 main branch forming in this n^ 



way two series on both sides 

 of it upon the dorsal side 

 of the branch (Fig. 336 a). 



The branchlets tend to- 

 wards the top (Figs. 334, 

 335a) issuing from the mother 

 branch with acute angles; 

 they are monosiphonous, 

 unbranched and, when fully 

 developed, composed of long 

 cylindrical cells about 20 n 

 thick and often more than 

 10 times as long, only taper- 

 ing slightly towards the 

 summit. The whole branchlet 

 reaches a length of about 

 1200 |a. The basal cell in the 

 branchlets is short, nearly 

 quadratic, and becomes more 

 or less immersed in the cor- 

 tical layer ; the summit of the 

 branchlet is obtuse. The 

 branchlets are rather persi- 

 stent ; in the older, lower part 

 of the fdaments they are 

 dropped' leaving only the 

 basal cells. 



At some distance from 

 the summit when the branch- 

 let» are already much devel- 

 oped the adventitious bran- 

 ches with continuous growth 

 are formed (Figs. 334, 335 a). These contribute to the ramifica- 

 tion of the plant and are issued now and then without any more 

 definite distance between them. They are mostly issued at the side 

 of a branchlet (Fig. 335 c). I have most frequently found them placed 



Fig. 334. Cottoniella arcuata nov 

 Upper parts of filaments. 



(About 45:1). 



spec. 



