436 BULLETIN OF THE BUREAU OF FISHERIES. 



Order i. Phaeosporeae Thuret. 



De Toni. 1895, P- 93- 



Thallus multicellular (in a few forms one to few celled), varying greatly in size and 

 form; asexual propagation by fragments of the thallus or special "brood buds" (pro- 

 pagula) or by laterally biciliate zoospores, or by nonmotile aplanospores ; sexual repro- 

 duction by motile, laterally biciliate gametes, similar or differing in form and size, or 

 by nonmotile eggs and laterally biciliate motile sperms ; spores and gametes produced 

 in organs (sporangia, gametangia) formed from ordinary vegetative cells or from special 

 cells ; sporangia and gametangia occurring on superficial portions of the thallus or arising 

 from the transformation of surface cells. 



KEY TO FAMILIES. 



o. Sporangia and gametangia occupying the place of branches of the frond or formed by the 

 transformation of segments or portions of these segments; longitudinal growth inter- 

 calary i. ECTOCARPACE^ (p. 436). 



oo. Sporangia and gametangia formed by the transformation or division of a superficial cell, 

 less often arising from the evolution of single segments of a segmented portion of the 

 frond; longitudinal growth by intercalary division equally distributed through the 



whole frond or persisting a longer time at the base; frond simple 2. ENCCELIACE^E (p. 442). 



aaa. Sporangia and gametangia occupying the place of assimilating filaments or formed by 



the partial transformation of assimilating filaments 6. 



b. Longitudinal growth basal or lasting longest at the base 3. ELACHISTEACE^ (p. 444). 



bb. Longitudinal growth terminal or subterminal: . . 4. CHORDARIACE/E (p. 445). 



0000. Sporangia and gametangia lateral on special segmented filaments arising from the frond c. 



c. Longitudinal growth subterminal 5. STILOPHORACE^E (p. 447). 



cc. Longitudinal growth trichothallic ; brushes of confervoid filaments at the ends of 



the short branches 6. SPOROCHNACE^ (p. 448). 



Family 1. ECTOCARPACEL/E (Agardh) Hauck. 



Frond consisting of a creeping filament, usually with more or less conspicuous 

 upright filaments arising from this, or of a one or two layered disk; usually monosiphon- 

 ous, occasionally divided once or twice here and there in a longitudinal direction; more 

 or less branched or subsimple ; growth in length by intercalary division ; sporangia and 

 gametangia occupying the place of branches of the frond, or formed by the transfor- 

 mation of articulations or segments of these articulations; organs of fructification 

 consisting of "unilocular sporangia," formed by the growth of a cell without formation 

 of cross walls, or of "plurilocular sporangia," formed by the growth and repeated divi- 

 sion of one or more cells; these usually occurring on different individuals, sometimes 

 apparently on the same individual; male and female gametes produced on the same or 

 different individuals. 



About 130 species described, many of them doubtful, in all seas, but most abundant 

 in the North Atlantic, mostly epiphytic. 



The method of reproduction is exceedingly various, even within a single genus. 

 The family seems to show the beginning of differentiation into asexual and sexual cells. 

 The products of the "unilocular sporangia" are asexual, either motile zoospores or 

 nonmotile aplanospores. The products of the "plurilocular sporangia" are asexual or 

 sexual, being all alike, giving either zoospores or isogametes, or of two sizes, giving either 

 zoospores of two sizes or heterogametes, or of three sizes, giving zoospores of two sizes 



