482 BULLETIN OF THE BUREAU OF FISHERIES. 



Order 3. Rhodymeniales Schmitz. 



Rhodymeninae. De Toni, 1900, p. 387- 



Carpogonial filaments and mother cells of the auxiliary cells occurring together in 

 pairs, nearly always united into definite procarps, the auxiliary cells usually cut off only 

 after fertilization. Gonimoblast arising from an auxiliary cell after the fertilized egg 

 has fused with this by means of a short carpogonial process, attached to a basal pla- 

 centa, cystocarps not completely immersed in the frond. 



KEY TO FAMILIES. 



a. Gonimoblast somewhat immersed in the thallus, filaments radiating from their point of 

 attachment on a median, thickened placenta within the fruit-bearing cavity, peri- 

 carp thick, perforated at the apex .b. 



b. Gonimoblast much branched, densely crowded and confluent, usually hemispherical- 



convex, carpospores borne at the apices of the branches singly or in chains; tetra- 



sporangia cruciately or zonately divided r . SPHAEROCOCC ACE/B (p . 482 ) . 



bb. Gonimoblast divided into several lobes successively developed, nearly all cells of 

 the lobes forming spores; tetrasporangia nearly always cruciately divided. 



2. RHODYMENIACE^S (p. 487). 



aa. Gonimoblast sessile in the thallus, formed within the fruit-bearing cavity, covered by 



the cortex of the thallus with a perforation at the apex c. 



c. Procarp situated in the median layer of the thallus, gonimoblast attached to the median 



thickened placenta, gonimolobes usually indistinctly formed, carpospores borne at 

 the apices of the fertile branches singly or in chains; tetrasporangia triangularly 



divided. 3. DELESSERIACE^ (p. 493). 



aaa. Gonimoblast attached to the thallus by means of a pedicel or broad base, entirely 



external or somewhat inclosed by the cortex in various ways d . 



d. Cystocarps attached to the thallus by means of a broad base or a short pedicel, gonimo- 



blast attached by a large fusion, central cell within a pericarp perforated at the 

 apex, carpospores large, single in the apices of the fertile branches, less often in 



chains; tetrasporangia triangularly divided 4. RHODOMELACE^ (p. 496). 



dd. Cystocarps entirely external or inclosed by the cortex, naked (without pericarp) or 

 more or less loosely enwrapped by their own branches, gonimoblasts single or 

 more often in pairs, usually divided into several lobes, carpospores formed from 

 nearly every cell of the fertile branches; tetrasporangia triangularly or cruciately 

 divided 5. CERAMIACE/B (p. 509). 



Family 1. SPHyHROCOCCACEjE (Dumort) Schmitz. 



Thallus terete or flattened, dichotomously or laterally branched, structure cellular 

 or cellular filamentous; tetrasporangia situated in the cortical layer, scattered over the 

 surface of the thallus or in nematheciumlike portions, usually zonately, less often cruci- 

 ately divided; antheridia variously formed; carpogonia usually numerous on the fertile 

 portions of the thallus, apparently closely associated with the cells which, after fertili- 

 zation, give rise to the auxiliary cells; cystocarps rather prominent, sometimes formed 

 in special branches and then supported by a quasi short stalk, pericarp often thick, 

 usually provided with an apical pore, often joined to the "nucleus" by sterile strands, 

 gonimoblast arising from the base of the fruit, richly branched, densely crowded and 

 confluent, usually hemispherical-convex, forming spores singly or in chains at the apices 

 of the fertile filaments. 



About 150 species in warm and temperate seas, especially in Australian regions. 



