448 The Ohio Naturalist. [Vol. IX, No. 4, 



10. Conjugatae. 1200 species. 



Unicelhilar or filamentous, unbranched, unattached, green, 

 mostly freshwater algae, with a single nucleus and with one or 

 more highly specialized chloroplasts with pyrenoids in the cells ; 

 reproduction by division and by zygospores formed by the con- 

 jugation of two similar or nearly similar cells, often joined bv the 

 development of a special conjugation tube. 



11. Siphoneae. 625 species. 



Coenocytic terrestrial or aquatic green algae usually filamen- 

 tous, more or less branched, and with or without transverse 

 septa; reproduction by zoospores, by ciliated gametes, or by true 

 sperms and eggs. 



12. Conferveae. 600 species. 



Simple or branched filamentous green algae, sometimes hav- 

 ing the cells in discs or sheets, usually attached, having normal 

 cells with one nucleus; reproduction by means of zoospores and 

 by motile gametes or by heterogametes, the egg being stationery ; 

 commonly with a primitive alternation of generations; chloro- 

 plasts one or more, usually with p3"renoids. 



Subclasses, Isogamae. 



Heterogamae. 



13. Phaeosporeae. 385 species. 



Normally brown-colored marine algae ranging from rather 

 simple filamentous forms to very large, highly developed organ- 

 isms with a distinct conducting tissue whose cells contain sieve 

 plates; usually attached, the frond often differentiated into stem 

 and leaf-like structures; reproduction by zoospores produced in 

 unilocular sporangia, and motile gametes produced in pluri- 

 locular sporangia; both types of sporangia exposed. 



14. Cyclosporeae. 316 Species. 



Medium to large, marine, brown algae, attached, branched, 

 and usually flatfish; reproduction by small biciliate sperms and 

 large non-ciliated eggs which are discharged and fertilized in the 

 water; reproductive organs sunken in conceptacles. 



15. Dictyoteae. 82 species. 



Erect, attached, marine, brown algae with fiat leaf-like fronds; 

 nonsexual reproduction by nonmotile tetraspores; sexual repro- 

 duction by means of non-ciliated eggs produced singly and 

 finally discharged from the oogonium, and sperms with one flagel- 

 lum produced in many-celled antheridia. 



1(). Bangieae. 46 species. 



Marine or freshwater red or purple algae with filamentous 

 or thalloid fronds ; reproduction by single thallus cells and by the 

 production of antheridia and oogonia from ordinary thallus cells, 

 the antheridium developing nonciliated sperms, the oogonium 

 which is without a distinct trichogyne usually developing a single 

 stationary egg. _i ^^^--.^.^ 



