44 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



Chaetophoraceae 



Filamentous plants, sometimes spreading and sometimes forming 

 disks, usually microscopic or nearly so, the cells in some genera bearing 

 long hairs; reproduction from vmdifferentiated or moderately differenti- 

 ated cells by biflagellate zoospores or by gametes of various degrees of 

 specialization. 



KEY TO GENERA 



1. Plants formed of relatively regular filaments, not developing 

 parenchymatous nodules 2 



1. Plants of creeping filaments composed of cells of irregular shape 

 and articulation, often anastomosing, commonly developing par- 

 enchymatous masses; hairs lacking Zygomitus 



2. Filaments differentiated into a basal layer which eventually bears 

 erect filaments; hairs absent or present, in which case they are 

 septate Pilinia 



2. Filaments chiefly creeping, without differentiation of special erect 

 branches; hairs setiform, continuous with the supporting cell 3 



3. Plants generally with wavy setae; in the jelly of larger algae, 

 rarely on stones or penetrating calcareous algae . . . Phaeophila 



3. Plants generally with straight setae; in the jelly of larger algae 

 or penetrating calcareous algae Ectochaete 



PILINIA Kiitzing, 1843 



Plants of branched creeping filaments, the horizontal layer of which 

 bears simple or forking erect filaments, sometimes ending in multicellular 

 hairs ; the cell structure showing a chromatophore which encloses the pro- 

 toplast ; reproduction by numerous biflagellate zoospores formed in ter- 

 minal or lateral rounded to clavate sporangia in the erect filaments, or 

 sessile on the horizontal filaments. 



KEY TO SPECIES 



1. Erect filaments reaching 400 /i, in length, basally 5-8 /x, diam., 

 terminating in articulate hairs P. maritima f. pacifica 



1. Erect filaments reaching 150 /x in length, 5-6 /a diam., widening 



upwardly to 6-8 fi, not terminating in hairs 



P. Lunatiae f. simplex 



