19 



The chromatophore is usually slightly developed (Figs. 9 and 

 10); it is parietal often with some long irregularly shaped pro- 

 longations ; in some of the cells it often consists only of a small 

 portion surrounding the 

 pyrenoid and lying at 

 the wall of the cell. 



The sporangia are 

 found either at the base 

 of the filaments upon 

 their upper side some- 

 times solitary, some- 

 times two or three to- 

 gether, or they may 

 occur upon short bran- 

 chlets given off from the 

 principal filaments. They 

 are mostly pedicellate 

 but sessile ones also 

 occur. The sporangia Fig 8 Acroeha!tiwn Sargassi nov . spec . 

 are oval-obovate (Fig. a, plant with sporangia, b, part of a filament 

 8 h QV thpir lono-Hi i with sporangia, c, part of a plant with carpo- 

 > ' gonia. (a, about 100 : 1, b, 500 : 1, c, 400 : 1). 



about 10^, their breadth 



about 7 fj.. 



This is the only West Indian species in which sexual organs 



were found. Specimens with antheridia were seen several times 



(Fig. 7). The antheridia occurred in pairs 

 along both sides of the small fertile branch- 

 lets (Fig. 10) but were now and then more 

 irregularly arranged. 



For a long time I searched vainly for 

 the carpogonia and finally I succeded in find- 

 ing a specimen in which some few carpogonia 

 undoubtedly were present. As Fig. 8 c shows 



Fig. 9. Acrochsetium they are bottle-shaped having nearly the same 



Sargassi nov. spec. 



Part of the thallus form as in other species. No later stages of 



with sporangia. The carpogonia were found. 



nethermost has been 1 . 



emptied and a new This plant seems to come very near to 



one is growing out Acrochsetium Dufourii Collins and I have been 

 again, (about 600: 1). . , . . , , 



in great doubt how far that plant is indeed 



only a young state of my species. But after having examined 

 the original material of Acroch. Dufourii, distributed in "Phyc. 

 Bor.-Am.", No. 1594 I think it is not. 



2* 



