80 RYTIPHLjEA. 



very slender, cylindrical, excessively branched in a distichous manner, the 

 branches very patent or divaricating, alternate, furnished with a second or 

 third series of similar patent ramuli, the apices very much involute. Cap- 

 sules unknown in this country ; receptacles of granules forming pinnate 

 tufts, either terminal or lateral. Colour pale purplish, becoming blackish 

 in drying. Substance somewhat cartilaginous, tender. A very curious 

 plant, forming, with some tropical, and several antarctic species, a dis- 

 tinctly marked little group remarkable for their amphibious habits. 



IV. RYTIPHL^A, Ag. [Plate 11, D.] 



Frond filiform or compressed, pinnate, transversely striate, 

 reticulated ; the axis articulated, composed of a circle of 

 large, tubular, elongated cells (siphons) surrounding a cen- 

 tral cell ; the periphery of several rows of minute, irregular, 

 coloured cellules. Fructification twofold, on distinct plants ; 

 1, ceramidia, containing a tuft of pear-shaped spores ; 2, 

 tetraspores, contained in minute, lanceolate pods (stichidia), 

 in a double row ; or immersed in swollen ramuli. Name, 

 pvng, a wrinkle, and pxoioj, the bark, because the surface is 

 transversely wrinkled (when dry). 



1. R. pinastroides, Gm.; frond terete, irregularly branched ; 

 lesser branches pectinato-pinnate ; the pinnae secund, with 

 their apices hooked inwards. Rhodomela pinastroides, Grev. 

 Alg. Brit. p. 104, t. 13; Hook. Br. FL ii. p. 294 ; Wyatt, 

 Alg. Danm. No. 112; Harv. Phyc. Brit. t. Ixxxv. Fucus 

 pinastroides, E. Sol. t. 1042. 



On submarine rocks, near low-water mark. Pgrennial. Fruiting in 

 winter. Southern shores of England, frequent. Frond 4 8 inches high, 

 cylindrical, subsimple at base, much branched above, the branches alternate 

 or secund, long, spreading in a fan-like manner, much divided, the lesser 

 ones set with secund, erect ramuli, about half an inch long, and either 

 straight, or, more generally, hooked at the extremity. The whole plant 

 marked, at short intervals, with transverse striae, giving it a jointed appear- 

 ance. Capsules minute, spherical, scattered on the ramuli ; tetraspores im- 

 bedded in the ramuli of distinct plants. Substance cartilaginous. Colour 

 a dull red, becoming black in drying. 



2. R, complanata, Ag. ; frond brown-red, compressed, 

 pinnate or bi-tripinnate, the lower pinnae short or abortive, 

 the upper long, straight, erect, virgate, once or twice com- 

 pounded ; pinnules subulate or bifid, erect, closely set ; the 

 axils acute. Harv. Phyc. Br. t. clxx. Pol. cristata, Harv. 

 in Mack. Fl. Hib. part 3, p. 205. 



On the rocky beds of shallow tide-pools, exposed, at low-water mark, to 

 full sunshine. Very rare. Perennial. Summer. South of England and 

 West of Ireland. Stem 2 or 3 inches high, erect, nearly simple below, de- 

 compound above, compressed, half a line in breadth, nearly equal through- 



