Ser. RnoDosPERMEii. Fam. Uhodymeniacea. 



Plate XCVL 



POLYSIPHONIA FORFEX, Harv. 



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

 gitudinally striate, composed of numerous cylindrial cells surrounding 

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

 cells). Fmctification : \, ovate or urceolate ceramidia, containing 

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

 branches. — Polysiphonia [Grev.), from nroXvi, many, and cncfxov, 

 a tube. 



Frons filiformis, plus minus articulata ; articulis longitud'maliter pluristriatis, 

 ex celhdis 4-20 cylindraceis cellulam centralem cingentibus formatis (nunc 

 celluUs minoribiis pluriseriatis corticatis) . Fruct.: \, ceramidia ; 2, tetra- 

 sporce in ramidis ultimis uniseriatce. 



Polysiphonia Forfex ; pale brownish-red, drying to dark red-brown ; 

 fronds subsolitary, 2-3 inches long, setaceous, cartilagineous, pellu- 

 cidly articulate, repeatedly dichotomous ; ultimate ramuli twice or 

 thrice forked, the tips incurved, acute, forcipate ; articulations 6-tubed, 

 shorter than their diameter ; ceramidia broadly ovate, suhsessile. 



P. Forfex ; pallide rufescens, siccitate fnsco-rubra ; frondibus subsoliiariis 2-3- 

 uncialibus crassis cartilagineis pellucide articulatis repetite dicJiotomis v. 

 abortu scorpioideo-secundis ; ramuUs ultimis bis terve furcatis apice acutisfor- 

 cipatis ! articulis 6-sipkomis diametro brevioribus ; ceramidiis lato-ovatis sub- 

 sessilibus. 



Polysiphonia forcipata, Harv. in Trans. R. I. Acad. n. 22. p. 541 {non 

 KiUz.) ; Alg. Austr. Exsic. n. 171. 



Hab. On Zostera and the smaller Algae. Eottnest Island and King 

 George's Sound, W. H. H., Garden Island, Fremantle, G. Clifton. 



Geogr. Distr. Western Australia. Tanega Island, Eastern Archipelago, 

 C. Wright! 



Descr. Root a small disc. Fronds erect, solitary or two or three together, but 

 not densely tufted, 2-3 inches long, as thick as hog's-bristle, repeatedly 

 and more or less regularly dichotomous. Old specimens are more irregular 

 and more densely branched than our figure represents ; in them the lateral 

 branches and their divisions alone retain the dichotomous character. 

 The smaller branchlets are most regularly forked, and the tips of the ra- 

 muli, which are acute, approach each other in pairs, like the arms of 

 scissors. The frond is pellucidly articulate throughout, the joints being 

 much shorter than their breadth in all parts of the frond. The siphons 

 are six, the central cell very small, and the lateral view of each siphon 



