474 University of California Publications in Botany [Vol. 8 



11. Gametangia cylindrical or very slightly tapering 12 



11. Gametangia decidedly fusiform 13 



12. Gametangia mostly on 1-2-celled pedicels 1. C. myrionematoides (p. 474) 

 12. Pedicels of gametangia very variable in height .3. C. nummuloides (p. 475) 



13. Gametangia 24-30/u long, 6-8ju broad 18. C. immixtum (p. 487) 



13. Gametangia 45-65^ long, 15-1Sm broad 9. C. coniferum fp. 479) 



13. Gametangia 50-75m long, 8-11/x broad 8. C. dubium (p. 479) 



13. Gametangia 60-130^ long, 18-28/* broad 10. C. serpens (p. 480) 



14. Erect filaments in part piliferous 16. C. speciosum f. piliferum (p. 485) 



14. Erect filaments not piliferous 15 



15. Terminal gametangia up to 400^ long 14. C. secundum fp. 483) 



15. Terminal gametangia up to 110/x long 15. C. secundum f. terminale (p. 484) 



1. Compsonema myrionematoides S. and G. 



Fronds forming small, circular to irregular cushions, 1-2.5 mm. 

 diam., prostrate portion strictly monostromatic, composed of closely 

 crowded, contorted, radiating filaments ; erect filaments unbranched, 

 cylindrical, 110-130/*. long; true hairs absent; cells of creeping fila- 

 ments cylindrical to irregular in form ; cells of erect filaments cylin- 

 drical, 7.5-8.5//, diam., 1-2 times as long, terminal often several times 

 as long ; chromatophore a slightly broken band in each cell ; zoo- 

 sporangia (?) broadly clavate, sessile or on short pedicels on the 

 creeping filaments, 35-50/x. long, 20-28/*, broad ; gametangia numerous, 

 cylindrical to fusiform, sessile or on short pedicels on the creeping 

 filaments, 50-7 0/x (up to 100/*) long, 9-12/*. broad. 



Growing on the stipe of Nereocystis Luetkeana. Pacific Grove, 

 California. 



Setchell and Gardner, Phyc. Cont. Ill, 1922, p. 361, pi. 36. fig. 1. 



There is but little choice as to the generic position of this small 

 alga. It forms small brown tufts or cushions of loose filaments. Very 

 frequently the gametangia are wider in the middle than at the ends 

 and have decidedly biseriate loculi. Because of the more or less loose 

 tufted character of the erect filaments and the partially biseriate 

 gametangia we have placed it with the genus Compsonema. 



2. Compsonema sessile S. and G. 



Fronds forming inconspicuous cushions up to 1.5 mm. diam., cir- 

 cular to irregular in outline ; creeping filaments contorted, closely 

 crowded, adhering firmly to the host, without rhizoids ; erect filaments 

 sparse, 20-24/*. high; true hairs absent; cells of creeping filaments 

 irregular in shape and size, 9-12/* diam. ; chromatophores band-shaped, 

 one in each cell ; zoosporangia unknown ; gametangia numerous, sessile 



