Ser. Hhodospekmi: k. Fam. Bhodomelacea. 



Plate XXXV. 



POLYSIPHONIA ROEANA, Harv. 



Gen. Char. Frond filiform, partially or generally articulate ; the joints lon- 

 gitudinally striate, composed of numerous cylindrical cells surrounding 

 a central cell (sometimes coated with one or several rows of smaller 

 cells) . Fructification : 1, ovate or urceolate ceramidia, containing a 

 tuft of pear-shaped spores ; 2, tetraspores, immersed in swollen 

 branches. — Polysiphonia (Grev.), from ttoXvs, many, and o-mjxov, 

 a tube. 



From fliformis, plus minus articulata ; articulis longitudinaliter pluristriatis 

 ex cellidis 4-20 cylindraceis celhdam centralem cingentibus formatis (nunc 

 cellidis minoribus pluriseriatis corticatis). Fruct. : 1, ceramidia; 2, tetra- 

 sporce in ramulis ultimis uniseriatce. 



Polysiphonia Roeana; rose-red; fronds (3-6 inches long) tufted, capil- 

 lary, soft, decompoundly much branched; branches alternate, often 

 subsecund, many times divided; ultimate ramuli filiform, elongate, 

 scattered, all very patent ; axils very wide ; articulations 4-tubed, the 

 lower 4-6 times, the upper twice, those of the ramuli 1-1 \ as long 

 as broad. 



P. Roeana ; punicea ; frond "ibus (3-6-uncialibus) caspitosis capillaribus mollibus 

 (chartce arete adhcerentibus) decomposite ramosissimis ; ramis alternis scepe 

 subsecundis pluries divisis ; ramulis ultimis filiformibus elongatis spai'sis 

 omnibus eximie patentibus ; axillis latissimis ; articulis pellucide 4^-siphoniis, 

 inferioribus diametro 4-G-plo, superioribus subduplo, ramulorum sesqid-longi- 

 oribus. 



Polysiphonia Eoeana, Harv. in Trans. R. I. Acad. v. 22. p. 540 ; Alg. 

 Exsic. Austr. n. 169. 



Hab. Dredged off Premantle, Western Australia, IF. H. H. and G. Clif- 

 ton, Esq. (1854). 

 Geogr. Distr. Not known elsewhere. 



Descr. Root discoid. Fronds tufted, 3-6 inches long, finer than human hair 

 (too coarsely drawn in our figure), excessively and very irregularly branched, 

 in a manner between dichotomous and alternate. The primary divisions 

 are properly dichotomous, but from frequent suppression of one arm of the 

 fork the filament becomes irregularly zigzag ; the secondary branches are 

 either alternate or very commonly secund, and are repeatedly compounded 

 in an irregularly forking or secund order. The main branches are not much 

 more robust than their divisions, and the lesser ones taper very gradually 

 to a point, the ultimate ramuli being about half the diameter of the branches. 



