6 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 30 Ser. 



with or without midrib, nerves or veins; with margin 

 entire, serrate, dentate, crenate, undulate, orlobed. Branch- 

 ing subdichotomous, subpinnate, subpalmate, or palmate, 

 with branches or segments entire, linear or expanded, 

 sometimes much prolonged. Stalk linear, flat, with or 

 without distinct midrib ; frequently becoming thickened and 

 cylindrical through wearing away of margin of frond and 

 renewed growth of remaining portion ; frequently twisted 

 by wave action; often persistent and freely proliferating. 



Midrib, when present, usually conspicuous, narrow or 

 wide, simple below, sometimes branched above, sometimes 

 evanescent or dividing into flabellate or anastomosing 

 nerves, frequently becoming thickened, stout and persist- 

 ent, freely proliferating. Nerves usually conspicuous, occu- 

 pying body of frond, margin, or apices, usually branching 

 freely, flabellate, free, or anastomosing, sometimes dividing 

 into minute and inconspicuous veins. Veins inconspicuous 

 or microscopic, occupying body of frond, margin or apices, 

 simple or branching, flabellate, free, or anastomosing, com- 

 monly evanescent and indistinguishable from ordinary tis- 

 sue of frond. 



Spoi-angia found on both surfaces of the frond, usually 

 in locally thickened portions, in sori of varied shape, con- 

 taining tripartite tetraspores. Sori minute and scattered 

 over the entire surface of the thallus, or large, forming 

 orbicular patches disposed irregularly over the surface; or 

 linear marginal patches; or lines arranged radially along 

 the margin ; or borne on marginal or surface proliferations 

 of varying size. 



Antheridia developed from the superficial cells of the 

 thallus, forming whitish patches scattered over the surface 

 of the frond, the latter frequently becoming rugose. 



Cystocarps scattered over both surfaces of the frond, or 

 arranged along the margin, or borne on marginal prolifera- 

 tions, usually large, projecting beyond the surface of the 

 thallus, opening by a carpostome. 



