1925] SetcheU-Gardner: Melanophyceae 475 



on the creeping filaments, cone-shaped to fusiform, 16-22/x long, 11-14/* 

 broad, many walls of the loculi oblique. 



Growing on the lamina of Hedopln/llum sessttt near the outer end. 

 Neah Bay, Washington. 



Setchell and Gardner, Phyc. Cont. Ill, 1922, p. 358, pi. 39, fig. 6. 



Compsonema sessile represents the extreme of the genus in the 

 direction of simplicity. There are no hair filaments, and it is doubtful 

 whether any of the erect filaments remain steiile. At times even the 

 cells of the basal layer seem to become a part of the gametangia, at 

 least more than one cell in the basal layer may be at the base of a 

 single gametangium. There would seem to be only a single modifica- 

 tion of Myrionema of the simplest type to produce this species, viz., 

 the change in the type of gametangium from uniseriate to pluri- 

 seriate. If we hold to the principal distinction between Compsonema 

 and Myrionema, it will be necessary to ally this species with the 

 former. It was found growing in company with StrebJonema aeci- 

 d hides f. pacifieum S. and G., which gave to the host a roughened 

 appearance, otherwise it probably would not be noticeable without 

 microscopic examination. 



3. Compsonema nummuloides S. and G. 



Fronds forming thin circular cushions, 7-12 mm. diam. ; prostrate 

 portion composed of radiating, much crisped, closely crowded filaments 

 following closely the irregularities of the host; erect filaments 

 unbranched, numerous, 300-400^ long, tapering slightly at both ends; 

 true hairs absent ; cells of creeping filaments very irregular in shape 

 and size ; cells of erect filaments cylindrical, (i-7/x diam. at the base, 

 3-8 times as long, 9-llfi diam. in the widest part, quadrate apical cell 

 6-7/x diam., 3-8 times as long; zoosporangia unknown; gametangia 

 mostly sessile or on short pedicels, some terminal on the erect filaments, 

 70-90ju (up to 140/*) long, 11-lSju broad ; loculi mostly 2-seriate. 



Growing on the pneumatocysts of Nereoeystk Luetkeana. Moss 

 Beach, San Mateo County, California. 



Setchell and Gardner, Phyc. Cont. Ill, 1922, p. 359, pi. 35, figs. 5, 6. 



Compsonema nummidoides forms thin, light brown cushions on 

 the pneumatocysts of the host. The whole cushion is a single plant, 

 circular in outline and attaining a diameter of twelve or more milli- 

 meters, although the majority of the plants are much smaller. Like 

 a typical Myrionema the plant starts from a single cell and by divi- 

 sions forms a series of filaments radiating in all directions with apical 



