F. Børgesen; List of species. 471 



Before entering upon a description of both plants I wish 

 to point out that both were found growing together upon the 

 same host plant, Dictyota indica, in the open sea at a depth 

 of about ten meters. Consequently they were both growing under 

 exactly the same external conditions, these no doubt highly in- 

 fluencing the habit of these plants. They were gathered in the 

 month of February. 



So far as 1 know the antheridial stands of Herposiphonia 

 are on the whole known only from the rather imperfect note by 

 Falkenberg in his monograph, 1. c, p. 308. 



The antheridial stands in the plant referred to H. secunda 

 are formed by the trichoblasts in the upper end of the branch- 

 lets (Fig. 428). A whole trichoblast is used to each antheridial 

 stand. They show great Hkeness to those found in Polysiphonia, 

 for instance to those in Polysiphonia ferulacea, comp, my fig. 



278. 



When fully developed the antheridial stands consist of a 

 basal stalk composed (mostly) of two cells, a shorter basal one 

 and a longer above it (Fig. 428); they are both without chroma- 

 tophores and have very thick walls. The lowermost cell is about 

 20 // high, that above from 40 fj. to 60// long and about 60 ju thick; 

 the peripheral wall is about 8 fi thick. Then follows the fructi- 

 ferous, polysiphonous part covered all over with the antheridia. 

 It is subcyhndrical, about 70 /^ thick below, 55 /i above and about 

 180 // long. In the specimens I have examined it consists of 4 to 

 5 segments, the central cells being clearly visible in the middle 

 (Fig. 428 a). From the middle of the central cells smaller cells 

 are given off; these are di-tri-tetrachotomously ramified several 

 times in a candelabrum-like manner. The outmost cells are the 

 antheridia. 



The whole antheridial stand ends in a terminal sterile cell, 

 about 50 fj. long, subpyramidal in shape and hke the cells in the 

 stalk with no chromatophores and with very thick wall. 



Fig. 428 b shows in the middle a young stage of the anthe- 

 ridial stand. From this it is seen that the antheridial part of it con- 

 sists of short segments becoming gradually polysiphonous. 



In the male plants found, the development of the branches 

 and branchlets is much reduced. In some of the plants no trace 

 of branches are found at all, in others these are only very rudi- 



