33 



que secundatim ordinata, rarius plus minus 

 sparsa. 



This species is an epiphyte especially 

 upon Centroceras but it is also found upon 

 other algae e. g. Gracilaria, Chsetomorpha, 

 Caulerpa taxifolia etc. It forms small more 

 or less dense tufts from 500 // up to double 

 this height. 



The basal part (Fig. 25 c, Fig. 26) con- 

 sists of short irregularly bent creeping 

 filaments, fusing together in the middle 

 into a small disc; it is composed of short 

 rather thickwalled cells. 



From the cells in the middle of this 

 disc several erect filaments gradually arise. 

 The filaments consist in their lower parts 

 of cells about twice as long as broad, 

 namely 8 10// broad and 16 22^ long. 

 Upwards the filaments taper gradually, 

 reaching near the summit about 6 7/*, 

 while the length of the cells is mostly 

 about the same throughout the whole fila- 

 ment, but thinner branches occur in which 

 the cells are only about 4/* broad while 

 on the other hand the length may reach 

 up to 30//. 



The erect filaments are branched often 

 from quite near the base, in the lower part 

 from all sides, higher up often quite uni- 

 laterally with the branches lying in the 

 same plane; the branches are again rami- 

 fied in the same way (Fig. 25 a) ; from this 

 the plant often gets an elegant pectinate 

 appearance. 



The cells contain a parietal chromato- 

 phore often with long prolongations along 

 the wall of the cells and with a large 

 lateral pyrenoid much protruding into the 



interior of the cell (Fig. 28) ; in some speci- 



,1 i . Fie 1 . 27. Acrochsetium se- 



mens the chromatophore is large covering ri * tum nov . spec. Habit 



nearly the whole wall with the exception of an erect ramified fila- 

 of a small part near the ends of the cells; ^ 



3 



