334 Vniversily of California 'Publications in Botany [Vol.7 



II. NEW SPECIES OF MYRIONEMA 



Introduction 



Critical study of an extensive series of material of small filamentous 

 species of Melanophyceae, mostly epiphytic upon larger Melanophyceae, 

 but in part epiphytic upon other algae and upon eef-grass, has brought 

 to light a rather surprisingly large number of little known or wholly 

 new species and forms on tlie Pacific coast of North America. Among 

 these is a series of similar organisms which we have grouped together 

 under the genus Myrionema, an account of which is presented in tliis 

 paper. 



We are recognizing as the principal characters of this genus : 

 (1) a monostromatic basal disk, composed of closely crowded, short 

 celled filaments radiating from a common center, starting from a single 

 cell, each filament having terminal growth, and branching by radial 

 bifurcation of the terminal cell; (2) springing outward from practi- 

 cally all of the cells of the basal disk, except at the margin, are erect 

 filaments all of which may be fertile, bearing either zoosporangia or 

 gametangia, or a part of which may remain sterile; (3) the loculi of 

 the gametangia are uniseriate. 



MjTrionema primarium sp. nov. 



Plate 34, figure 12 



Frondibus pulvinulos orbiculares, 0.5-1.25 mm. diam., formantibus; 

 parte prostrata filamentis regulariter radiantibus arete compactis. 

 formante ; filamentis erectis eramosis, dense stipatis, e cellula quaque 

 filamentorum repentium oriendis; pilis veris numerosis, per medium 

 frondis promisque sparsis; cellulis filamentorum erectorum 4-4.5(1 

 diam., inferne quadratis. cellula apicali juvena 2-3-plo longioribus; 

 cellulis pilorum verorum 4-5/x diam., 4-6-plo longioribus; zoosporangiis 

 ignotis; gametangiis in filamentis repentibus sessilibus per transfor- 

 matione filamenti toti quisque erecti oriendis, maxime stipatis, in medio 

 frondibus longitudine equalibus, prope niargines breviorilms. eylin- 

 dricis, 55-56//, longis. 5-()ju, latis, obtusis nut apice leviter attenuatis. 

 cellula apicali acute conica. 



Growing on the outer end of the young blade of Costaria costata 

 in the lower littoral and the upper sublittoral belts. Oregon (Coos 

 Bay) to central California. Type, Gardner, no. 2764 (Herb. Univ. 

 Calif., no. 207012), mouth of Coos Bay, May. 



