1922] Setchell-Gardner : Phycological Contributions 339 



This small epiphyte seems to be restricted in its habitat to the 

 above named host. The only known localities in which the host has 

 been observed are those mentioned above. The material from each 

 locality is richly infested by this epiphyte. The host, richly infested, 

 was distributed by Miss Josephine Tilden in her American Algae 

 (Exsicc), no. 609, under Eenfrewia parvula Griggs. 



It seems very closely related to Mi/rionema foecundum f . simplicis- 

 sivmm. The differences are in the larger measurements of all of the 

 parts, the presence of numerous, larger, so-called ascocysts, occurring 

 in groups (see plate 32, figure 7), or scattered among the gametangia, 

 in the presence of well developed hairs, and in the more convex upper 

 surface of the mass of erect filaments. 



Myrionema corunnae f. uniforme forma nov. 



Plate 33, figures 4, 5 



Frondibus pulvinulos irregulares 0.5-1.5 mm. diam. formant- 

 ibus; filamentis repentibus stratum compactum augmentatione 

 peripherica efficientibus ; pilis veris deuntibus ; filamentis erectis 

 eramosis. apice leviter attenuatis, SO-lOO/x (usque ad 120ju,) altis; 

 cellulis filamentorum erectorum 4.5-5.5/a diam., 1-1.5-plo longioribus; 

 "ascocystis" sparsis, clavatis; gametangiis stratum solidum com- 

 pactum, ordine palorum, centro altitudine aequalibus, ad margines 

 gradatim diminuendis, plerumque sessilibus, nunc pedicellis 1-3 cell- 

 ulis compositis suffultis, SO-lOO^u, altis, 6-6. 5/x latis; loculis uniseriatis. 



Growing on the blades of Costaria costata, Liminaria Sinclairii, and 

 Alariu marginata. Central California (Moss Beach in San i\Iateo 

 County, Fort Point in San Francisco). Type, Gardner, no. 4473 

 (Herb. Univ. Calif., no. 207023), San Francisco, July. 



Forma uniforme differs from the species as described and figured 

 by Sauvageau (1897, 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 grow 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. 



