^74 



F. B0RGESEX 



Fig. 19. Acrochaetium Ralfsiae now spec, a plants 

 with sporangia, c. 260 /i; b a branch, c. 300 /i. 



like the mother filament, but most 

 of them remain short consisting 

 of a single cell with a terminal 

 sporangium. 



The sporangia are oblong- 

 lanceolate, 9—12 ;i thick and 

 17 — 20 jj. long. 



The filaments taper a little 

 toward their summit; most of 

 them end in a broadly rounded 

 cell, but some are narrowed 

 into a pseudo-hair-like cell, 

 which is 40 — 50 u. long or even 

 longer and only I a thick near 

 the tip. 



The length of the whole 

 plant is about '/a — 1 mm. 



The cells contain a well de- 

 veloped parietal chromatophore 

 with a large parietal pyrenoid. 



By its more or less den- 

 sely clustered endophytic fila- 

 ments the West Indian Acr. plia- 

 celorhizum reminds somewhat of 

 this species, but in all other 

 respects it differs widely. 



Area of distribution: En- 

 demic. 



Fam. Chaetangiaceae. 



Galaxaura J. Ag. 



Sectio I. Rhodura Kjellm. 



G. collabens J. Ag. — Fig. 20. 



J. Agardh, Till Algernes Systematic, VII, p. 74. Kjellman, F. R., Om Floride- 

 Slagtet Galaxaura, p. 46. 



Some rather large specimens (Fig. 20 a), 6—7 cm high, densely covered 

 with short assimilating filaments are referable to this species as being in good 

 accordance with the description of KjELLMAN. 



The assimilating filaments are evenly distributed over the surface of the 

 thallus. The plant is irregularly subdichotomously ramified, the joints being 

 of rather variable length, 1 — I V2 cm long or more, sometimes as much as 

 3 cm long ace. to KjELLMAN. The thallus is terete, often a little thickened 

 toward the apex, the uppermost joints becoming slightly clavate. 



