1925] SeicluU-Gardncv: Melanophyceae 459 



in the center, g:radually diminishing toward the periphery, mostly 

 sessile, some on 1-3-celled pedicels, 80-100|U, high, 6-6.5ja diam. ; loculi 

 uniseriate. 



Growing on the blades of Costaria costata, Lammaria Sinclairii 

 and Alaria marginata. Central California (Moss Beach, San Mateo 

 County, and Fort Point in San Francisco). 



Setchell and Gardner, Phyc. Cont. II, 1922, p. 339, pi. 33, figs. 4, 5. 



Forma uniforme ditfers from the species as described and figured 

 by Sauvageau (1898, pp. 77-82, repr., figs. 14 A-F) in having no hair 

 filaments, in having no branched gametangia, in having "ascocysts, " 

 and in having slightly different dimensions. 



There are some differences in the size of the plants we have found 

 growing on different hosts in central California. The plants chosen 

 as the type of the form grew on the blades of Alaria marginata at 

 Fort Point, San Francisco. Very generally, this species of Alaria has 

 delicate grooves obliquely radiating from the midrib to the margin. 

 The presence of these grooves is often accentuated by the growth of this 

 minute Myrionema, usually so numerous as to be confluent, so that the 

 individuals cannot be detected except by microscopic examination. 



4. Myrionema corunnae f. angulatum S. and G. 



Fronds forming microscopic cushions, irregular in outline, among 

 other small algae on the host ; creeping filaments regularly radiating 

 when undisturbed ; erect filaments unbranched, densely crowded, 

 120-140/A long ; true hairs absent ; cells of creeping filaments 4-4.5/x 

 diam., mostly quadrate ; cells of erect filaments cylindrical, 4—4.5/* 

 diam., 1.5-3 times as long; zoosporangia and "ascocysts" unknown; 

 gametangia cylindrical, slightly attenuated at the apices, terminal on 

 6-10-celled pedicels, 35-45/a (up to 60/x) long, 4-6.5/x broad, many 

 partitions of the loculi oblique. 



Growing on the cysts of Egregia Menziesii. Cast ashore near the 

 "Cliff House," San Francisco, California. 



Setchell and Gardner, Phyc. Cont. II, 19-22, p. 340, pi. 33, figs. 6, 7. 



This form is to be distinguished from the species as described by 

 Sauvageau (1898, pp. 77-82, repr.) by the absence of hairs, the 

 presence of sterile erect filaments, the gametangia mostly on longer 

 pedicels and by the very small size of the loculi, often produced by 

 perpendicular and slanting walls. In part, the gametangia seem pluri- 

 seriate, caused by the division of some of the original cells into small, 

 angular loculi. 



