334 THE PLANT PHYLA 



Family 7. Coscinodiscaceae. Cells short, ends not 

 ribbed. — Coscinodiscus. 



Family 8. Actinodiscaceae. Cells short, ends rib- 

 bed. — Actinodiscus, Arachnoidiscus. 



Family 9. Eupodiscaceae. Cells short, ends with 

 " eves." — Eupodiscus, Actinocyclus. 



Family 10. Soleniaceae; 11, Chaetocerotaceae; 12, 

 Biddulphiaceae; 13, Euodiaceae; 14, 

 Anauliaceae; 15, Rutilariaceae. 

 Order Naviculales. Flat Diatoms. Filaments flattened, 

 usually fragmented into single cells. 



Family 16. Tabellariaceae. Mostly filaments, cells 

 short, rectangular in side view. — 

 Grammatophora, Rhabdonema. 



Family 17. Meridionaceae; 18, Fragilariaceae. 



Family 19. Naviculaceae. Cells single, end with 

 central slit. — Navicula, Amphipleitta. 



Family 20. BaciUariaceae; 21, Surirellaceae. 



Phylum IV. SIPHONOPHYCEAE. The Tube Algae 



Normally chlorophyll-green filaments composed of one or more 

 coenocytes 



Class 7. VAUCHERIOIDEAE. Lower Tube Algae. Fila- 

 ments septate or tubular. (Sp. about 



400.) 

 Order Cladophobales. The Cladophoras. Septate, the 



segments coenocytic. 

 Family 1. Cladophoraceae. Unbranched or branched, 



isogamic. — Cladophora, Pithophora. 

 Family 2. Sphaeropleaceae. Unbranched, h e t e r o- 



gamic. Sphaeroplea. 

 Order Siphonales. Green Felts. Tubular, irregularly 



branched, chlorophyUose. 

 Family 3. Phyllosiphonaceae. Endophytic. — Phyl- 



losiphon. 

 Family 4. Codiaceae. Filaments compacted into a 



large plant-body. — Codium, Peni- 



cillus. 

 Family 5. Vaucheriaceae. Filaments single, free. — 



Vaucheria. 



