290 



of the branches and branchlets, I at first took it for Herposi- 

 phonia secunda. But after having examined it in more detail 

 I have arrived at the conclusion that it is nothing else than a 

 form of H. tenella. 



The figure (Fig. 289) shows a part of this plant. 



Quite a peculiar feature of this plant was to be found in 

 the facts that the ordinary number of segments between the 

 branches were not maintained, that the branchlets were wanting 

 in some segments, leaving the latter bare, and finally that the 

 branches were often quite rudimentary. This is clearly seen in 

 the diagram of the same part of the plant as shown in Fig. 289. 



Beginning from the left end of the figure we at first have a 

 branchlet on the right side and one on the left, then a rudi- 

 mentary branch on the same side; then follow three segments 

 with branchlets and one with a branch placed quite in accord- 

 ance with typical H. tenella. But then we have a bare segment 

 and after that one with a branchlet placed on the left side, then 

 follows a segment with a branch also to the left; then again we 

 have a bare segment, then one with a branchlet to the right, 

 and then a segment with a branch on the same side. The arrange- 

 ment of branches, branchlets and bare segments in these two 

 last mentioned groups of segments agrees very much with that 

 found in H. secunda, the .only difference being that in the true 

 Herposiphonia secunda we have two consecutive bare segments, 

 whereas in the present case there is a single one only. After these 

 groups followed three segments with branchlets and one with 

 a branch placed in the ordinary way as found in H. tenella, and 

 then again a group ol segments deviating as to their branching 

 from the type, like those already described. As pointed out above, 

 it cannot be denied that this abnormal branching largely recalls 

 that found in H. secunda, a modification which FALKENBERG has 

 also noted in this species (cfr. FALKENBERG, 1. c., p. 307, pi. 3, fig. 

 11). But as other parts of the plant were branched in accordance 

 with the typical form I have no hesitation in referring my plant 

 to H. tenella. Yet in another point this plant differs from the 

 true H. tenella, recalling H. secunda, viz. in the very short seg- 

 ments, these 'being much shorter than their breadth, for instance 

 in the branchlets: length = = about 25//, breadth = = about 35 //. 



FALKENBERG discusses this question ho\v far Herposiphonia 

 secunda really is to be considered as an independent species 

 or is nothing else than a form or variety of H. tenella. Leav- 



