37! 
torulose and often strongly constricted; sometimes only one of. the 
branches is developed (cfr. Fig. 6 €). The thickness of these fila- 
ments is about 14—17 4; the uttermost part of them often growing 
Fig. 5. Avrainvillea spec. 1/1. 
thicker (19—25 4). The chromatophores are spindle-shaped and 
contain a pyrenoid (fig. 6 7). 
Only a single specimen was found, viz: St. Jan, Maho Bay, 
where it was growing in a depth of about 16 meters of water. 
This plant I had at first referred to Avr. levis Howe (Phyco- 
logical studies — II, Bulletin Torrey bot. Club, Vol. 32, p. 565) and 
