rhizoids (Fig. 1 f) which grew out from the lowest part of the fila- 
ments and attached themselves to sand and gravel. The filaments 
were not very richly branched and above the dichotomy there was 
usually no constriction or it was only present in one of the fila- 
ments (cfr. Fig. 1 a, b, c, d, e). The thickness of the filaments was 
about 140 4. The filaments were thin-walled; small spindle-shaped 
A 
Fig. 1. Avrainvillea comosa (Bail. et Harv.) Murray et Boodle. 
Compare text. a—f about */1; g about 17/1. 
chromatophores occurred in the wall-plasma (Fig. 1 g); in these I 
have not seen pyrenoids nor have I found amylum. 
The plant was found: St. Jan, off America Hill in the sea 
to the west of Tatch Island near Tortola in about 30 meters of 
water. 
My plant differs from specimens of the Eastern Hemisphere 
which I have seen by having lesser branched filaments, by having 
