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



219 



main stem ; below, the side-branches grow out to long filaments like 

 the main stem ; higher up they are shorter ; in the uppermost 

 part the ramification is subdichotomous. The plant is not corti- 

 cated and hairs do not occur. 



The tetrasporangia are generally tetrahedrally divided, though 

 cruciately divided ones occur too (Fig. 206 A). They are sessile, 

 oblique-obovate or nearly roundish when ripe and 35—40 fx broad. 



The cystocarps are, when 

 fully developed, irregularly lobed, 

 binate. I have only found a 

 few procarps ; from these it 

 seems evident that the carpo- 

 gonial branch is four-celled ; the 

 carpogonium has a rather long 

 trichogyne (Fig. 206 C). 



Antheridial plants had not 

 been seen when I previously 

 examined the plant ; these have 

 now been found by renewed 

 examination (Fig. 207). The 

 antheridial stands occur in the 

 same places as the tetraspor- 

 angia, lining the upper (inner) 

 side of the filaments. Often 

 they are found only at the 

 summit of the cells, sometimes 

 they occupy nearly the whole 

 upper side of these. They con- 

 sist of a system of short branch- 

 lets in which the uppermost 

 cells are the antheridia. The 

 antheridial stands in the West 

 Indian plant differ rather much from those figured by Buffham^). 

 In his specimens these have a single short axis while in the West 

 Indian plant, as mentioned above, the antheridial stand is composed 

 of several short branchlets. 



The tetrasporangia, cystocarps and antheridia occur in sepa- 

 rate plants. 



The chromatophores are parietal and consist of shorter or 



1) BuFFHAM, T. H., Notes on the Florideæ and on some newly-found 

 Antheridia (Journ. of the Queckett Microsc. Club, vol. I, Ser. II, 1884, 

 p. 341, pi. X, figs. 4, 5). 



Fig. 205. Callithamnion hyssoides Arn. 



Part of a tetrasporic plant. 



(About 60 : 1). 



