PHAEOPHYCEAE 337 



Order ECTOCARPALES. Zoospores and isogametes similar 

 and motile. 



Family 1. Ectocarpaceae. Mostly filamentous, sim- 

 ple or branched, with zoospores and 

 gametes. Ectocarpus, Streblonema. 



Family 2. Myriotrichiaceae;3, Choristocarpaceae; 4. 

 Elachistaceae; 5, Chordariaceae; 6, 

 Stilophoraceae; 7, Spermatochnaceae; 

 8, Sporochnaceae; 9, Encoeliaceae; 10, 

 Desmarestiaceae; 11, Arthrocladia- 

 ceae; 12, Sphacelariaceae; 13, Ralf- 

 siaceae; 14, Striariaceae; 15, Dictyo- 

 siphonaceae. 



Family 16. Laminariaceae. Large, parenchymatous, 

 usually stalked, with zoospores only. 

 Laminaria, Alaria, Postelsia, Nereo- 

 cystis, Macrocystis. Egregia. 



Order CUTLERIALES. Zoospores and heterogametes dis- 

 similar and motile. 



Family 17. Cutleriaceae; 18, Splachnidiaceae. 

 Order TILOPTERIDALES. Zoospores and heterogametes dis- 

 similar, eggs non-motile. 



Family 19. Tilopteridaceae. 

 Class 11. DICTYOTINEAE. Reproductive organs external, 



heterogamic. (Sp. about 130.) 

 Order DICTYOTALES. Plants erect, flat, leaf-like. 



Family 20. Dictyotaceae. Dictyota, Padina, Zonaria. 

 Class 12. CYCLOSPOREAE. Rockweeds. Reproductive or- 

 gans in sunken conceptacles, hetero- 

 gamic. (Sp. about 350.) 

 Order FUCALES. Usually flattish, branched. 



Family 21. Durvillaeaceae. Conceptacles on vegetative 

 parts of plant. Durvillaea. 



Family 22. Himanthaliaceae. Conceptacles on long 

 branches arising from a vegetative 

 cup. Himanthalia. 



Family 23. Fucaceae. Conceptacles on ends of vegeta- 

 tive branches. Fucus, Ascophyllum. 



Family 24. Sargassaceae. Conceptacles on small 

 lateral branches. Sargassum, Hali- 

 drys. 



