1922] Setcliell-Gardner : Phycological Contributions 395 



of its parts. It can readily be distinguished from the other two species 

 with which it is associated by the large size of the gametangia. No 

 zoosporangia have been observed. We take pleasure in dedicating this 

 species to ]Mrs. H. D. Jolmston, who collected the host and donated it 

 to the Herbarium of the University of California with several other 

 interesting forms from San Pedro, California. 



Streblonema aecidioides f. pacificum forma nov. 



Plate 44, figures 8, 9 



Frondibus microscopicis, supra superficiem hospitis ut maculas 

 elevatas 75-150/i, diam. notatis ; parte vegetativa stratum plus minusve 

 parenchymaticnm exigue infra stratum superficiale hospitis positum 

 et infra filamenta pauca radiciformia in hospitem profundiore pene- 

 trantia emittens formantibus; filamentis erectis omnibus fructiferis 

 filamentis paucis, piliferis in centre frondis positis exceptis; cellulis 

 filamentorum piliferorum 4— 5.5/x diam.. inferne quadratis, superne 

 5-8-plo longioribus, evaginatis; zoosporangiis( ?) anguste clavatis, 

 sessilibus, 22-28/i, longis. apice 8-12/i, latis; gametangiis numerosis, 

 dense aggregatis, eylindricis, in strato prostrato sessilibus, 45-55|U, 

 longis, 5-6.5|Li latis ; loculis uniseriatis. 



Growing within the lamina of HedopJiyllum sessile (Aresch.) 

 Setchell, near the outer end. Neah Bay, Washington. Type, Gardner, 

 no. 3866a (Herb. Univ. Calif., no. 207002), May. 



Streblonema aecidioides f. pacificum seems very closely related to 

 the Ectocarpus aecidioides of Rosenvinge (1893, p. 894), found grow- 

 ing in Greenland on Laminaria longicruris and L. Groenlandica. It 

 differs only in minor details as to the dimensions of the parts. Regard- 

 ing the zoosporangia we have to speak with uncertainty. As figured 

 by Rosenvinge, the Greenland plant has them well developed and pro- 

 ducing zoospores. They are in distinct "aecidia" and apparently on 

 distinct nonsexual plants. In our species they likewise appear to be 

 on nonsexual plants. In ours there is no indication of the production 

 of zoospores. They are possibly too young, or possibly they are 

 abortive organs so commonly met with in various other genera on our 

 coast, the nature of which is still an open question. This form seems 

 to enter the host from the surface and after penetrating to the second 

 layer of cells spreads out horizontalh^ between the surface layer and 

 the second layer. Later, filaments arise from the under side of this 

 layer and penetrate among the cells of the host, apparently never 

 entering them. Finally from the upper surface each cell in the central 

 region of the layer gives rise to a filament and the mass acting together 



