GROUP I. THALLOPHYTA : ALGJ) : PHJ}OPHYCE^E. 257 



The Phaeophyceae may be classified as follows : 

 Unicellular Forms : 



Order 1. S.yngeneticae : no sexual reproduction. 



Order 2. Diatomacese : sexual reproduction isogamous by aplanogametes. 

 Multicellular Forms : 

 Series (a) Phasosporeae : sexual reproduction isogamous by planogametes ; 



asexual by zoospores (in some cases by zoogonidia). 

 Order 3. Ectocarpaceae : including the families, 



Ectocarpeae (Ectocarpus, Pylaiella, Streblonema, etc). 



Choristocarpeae (Choristocarpus, Discosporangium). 



Myriotricheas (Myrotrichia). 



Myrionemeae (Myrionema, Microspongiurn, etc.). 



ElachisteaB (Elachista, Giraudia, etc.). 



Desmarestieae (Desmarestia, Arthrocladia). 



Spermatochneas (Spermatochnus). 



Sphacelarieaa (Sphacelaria, Stypocaulon, Chaetopteris, Clado- 



stephus, etc.). 

 Order 4. Encceliaceas ; including the families, 



Mesogloeeae (Chordaria, Mesogloaa, Castagnea, etc.). 



Sporochneae (Sporochnus, Carpomitra). 



Striarieae (Striaria, Stictyosiphon, etc.). 



Stilophoreae (Stilophora). 



Dictyosiphoneae (Dictyosiphon, etc.). 



Scytosiphoneae (Scytosiphon, Colpomenia, Phyllitis, Aspero- 



coccus.) 



Punctarieas (Punctaria, etc.). 



Order 5. Laminariaceae (Laminaria, Alaria, Chorda, etc.). 

 Order 6. Cutleriacese (Cutleria, Zanardinia). 



Series (6) Phseogamas : sexual reproduction oogamous ; asexual, wanting, 



or by non-motile spores : no gonidia. 

 Order 7. Tilopteridaceae. 

 Order 8. Dictyotaceae. 

 Order 9. Fucaceae. 



Order 1. Syngeneticae. Body unicellular, the cells being held together by 

 mucilage, forming a colony. Eeproduction by division, and by asexually pro- 

 duced spores. 



This order includes two genera, Hydrurus and Chromophyton ; in the former 

 the colony consists of many cells and is attached, in the latter it consists of 

 eight cells and is unattached. 



In Hydrurus, each cell is an ellipsoidal mass of protoplasm, enclosing a 

 nucleus, one or two contractile vacuoles, and one or two chromatophores in the 

 form of a plate or ribbon each containing a pyrenoid. The cells multiply by 

 division. Asexual reproduction is effected by means of zoospores, formed by 

 division of a cell into two or four, which are set free by the disorganisation of 

 the investing mucilage and move by means of a single cilium ; these come to 

 rest, and each gives rise by division to a new colony. Also by means of rest- 

 ing-spores formed one from each vegetative cell. 



V, S. B. S 



