360 UnivcrsiUj of California Publications in Botany [Vol. 7 



Compsonema nummuloidcs forms tliin, liy:lit brown cushions on the 

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

 cin-iilar in ontlino and attaining a diameter of twelve or more milli- 

 nu'tcrs, although the majority of the plants are much smaller. Like 

 a typical Mjjrionnno the plant starts from a single cell and by divisions 

 forms a series of filaments radiating in all directions with apical 

 growth and dichotomous branching, by the splitting of the apical cell, 

 thus forming a continuous monostromatic layer of cells. Beginning 

 in the center, practically every cell in each radiating filament of the 

 basal layer gives rise successively to an erect filament, about two- thirds 

 of which are fructiferous, the others remaining sterile. A very large 

 majority of the gametangia are sessile or on short pedicels, thus 

 occupying a zone near the creeping filaments, a Myrionematoid char- 

 acter, but the remainder of the filaments continue to grow and attain 

 a length of 300-400ju,. Some of these filaments are terminated by 

 relatively short gametangia. This is one of several species with this 

 general method of development which has been found growing only 

 on the above mentioned host, differing from each other and from the 

 type of the genus, T. gracile Kuckuck, in the size of the plant as a 

 whole, in details of dimensions of their parts, in the presence or absence 

 of zoosporangia and hairs, in the position of the gametangia, and 

 in the relative amount of sterile filaments. It seems to form a 

 fairly compact group ])ut with overlappings, however, in the genera 

 Strehlonema, Myrionema, and Hecatonema. 



Compsonema fasciculatum sp. nov. 



Plate 38, figures 7-9 



Frondibus flocculos micro.scopicos plus minusve confluentes for- 

 mantibus; filamentis repentibus tortuosis. hospitem sine ramulis 

 radiciformibus adhaerantibus; filamentis erectis prope basim ramosis. 

 90-130/x longis, basim apiceque attenuatis, non piliferis, ad dissepi- 

 mentaconstrictis; pilis verisdeuntibus; cellulis filamcntornm ei-ectorum 

 in parte latissima, 10-1 4/x, diam.. 1-2-plo longioribus; zoosporangiis 

 ignotis; gametangiis forma moderate irregnlaribus. conicis usque ad 

 fusiformibus, 35^5/x longis, 12-18/a latis; pleruiiKinc lateralibus. brevi- 

 pedicellatis. 



Growing on Gigartina radida f. Pacific Grove, California. Type, 

 Gardner, no. 4503 (Herb. Univ. Calif., no. 207042), December. 



This species is allied here rather than with Edocarpus because of 

 its extremely small size and its creeping, fasciculate habit. 



