i 



14 Charles E. Bcssey 



This phylum probably originated in the vicinity of the Ulotrich- 

 accae in the Protophyceae. The addition of phycophaein is prob- 

 ably related in some way to the marine habitat of the plants. 



Class 9. PHAEOSPOREAE. Reproductive organs external, 

 on the surface, or upon special branches ; propagation usually by 

 zoospores produced in unilocular sporangia^ and generation by 

 isogametes or heterogametes, produced in multilocular sporangia. 



Order Ectocarpales (Isogomcae). Reproductive cells (zoo- 

 spores and isogametes) similar and motile. 



Family i. Ectocarpaceae. Plants mostly filamentous, simple or 

 branched; both unilocular and multilocular sporangia present. 

 Ectocarpus, Strehloncma. (Pf. I, 2, 182.) 



Family 2. Myriotrichiaceae. Plants filamentous, densely 

 clothed with short branches ; both unilocular and multilocular 

 sporangia present. Myriotrichia. (Pf. I, 2, 214.) 



Family 3. Choristocarpaceae. Plants filamentous, unbranched; 

 both unilocular and multilocular sporangia present. Pleurocladia, 

 Choristo carpus. (Pf. I, 2, 190.) 



Family 4. Sphacelariaceae. Plants erect, branched, usually 

 massive, rarely a simple row of cells ; both unilocular and multi- 

 locular sporangia present. Sphacclaria, Halopcliis, Stypocaulon. 

 (Pf. I, 2, 192.) 



Family 5. Ralfsiaceae. Plants consisting of leathery layers of 

 cells on rocks, etc. ; both unilocular and multilocular sporangia are 

 present. Ralfsia. (Pf. I, 2, 240.) 



Family 6. Encoeliaceae. Plants from filamentous to club- 

 shaped, globular, and reticulated ; both unilocular and multilocular 

 sporangia are present. Pnnctaria, Phyllitis, Soranthcra. (Pf. I, 



2, 197- ) 



Family 7. Striariaceae. Plants parenchymatous, variously 

 branched, growing by a subterminal meristematic region; both 

 unilocular and multilocular sporangia are present. Phloespora, 

 Striaria. (Pf. I, 2, 204.) 



Family 8. Arthrocladiaceae. Plants filamentous above, paren- 

 chymatous below, with a subterminal meristematic region, co- 

 piously branched. The multilocular sporangia arise above the 

 growing region. Arthrocladia. (Pf. I, 2, 209.) 



288 



