1'2G RHODYMENIA. 



wedge-shaped fronds rise irregularly from a mass of entangled creeping 

 stems. Tubercles sessile, ou tbe disk or margin, generallj- near the tips of the 

 frond. Tetraspores ternate, forming oval cloudy spots in the expanded tips 

 of the segments. Colour a fine pinky-red. Substance of the stem cartila- 

 ginous, of the frond membranaceous, somewhat rigid, imperfectly adher- 

 ing to paper. 



4. R. cristata, L. ; frond semicircular, membranaceous, 

 sub-dichotomous, the segments somewhat dilated upwards, 

 repeatedly subdivided, the divisions alternate, decurrent, la- 

 ciniate at the ends ; tubercles spherical, imbedded in the 

 margin of the frond." Grev. — Grev. Alg. Brit. p. 89 ; Hook. 

 Br. Fl. ii. p. 290. Sphterococcus cristatus, Grev. Crypt, t. 

 85. 



Parasitical on the stems of Laminaria digitata; very rare. Annual. 

 July. Seashore at Wick, Caithness, Messrs. fiorrer and Hooker; Frith 

 of Forth, Dr. Greville ; Berwick, Dr. Johnston ; Shetland, Prof. Forbes ; 

 Orkney, Dr. M^Bain. — " Fronds about an inch long, divided near the base 

 into several main branches, flat and even, entire at the margin, linear or 

 dilated upwards, about a line in width, the branches again dividing once 

 or twice subdichotomously, and then bearing numerous other smaller seg- 

 ments in an alternately pinnatifid manner, decurrent and cleft or laciniated 

 at the apices; every division has a tendency to dilate upwards, so that the 

 circumference of the frond is extended and crowded. Fructijication : ses- 

 sile, spherical, dark red tubercles, half the size of poppy-seed, usually 

 occurring towards the extremity of the branches. Substance membrana- 

 ceous, or very slightly cartilaginous, adhering closely to paper in drying. 

 Colour a rose red, nearly similar lo that of Delessena alata." — Grev. Alg. 

 Brit. p. 90. Quite a northern species, and very rare on our coasts. 



5. R. ciliata, L. ; frond thick, sub-cartilaginous, full pur- 

 plish-red, rising from a short stalk, lanceolate, irregularly 

 pinnated with lanceolate or cleft segments, attenuated at 

 base; margin (and often the disk) furnished with simple, 

 subulate cilia, which bear the tubercles at their extremity ; 

 tetraspores zoned, forming cloud-like patches over the disk ; 

 root fibrous, creeping. Grev. Alg. Brit. p. 90 ; Hook. Br. 

 Fl. ii. /?. 291; Wyatt, Alg. Danm. No. 67; Harv. Phyc. 

 Brit. t. cxxvii. F. ciliatus, E. Bot. t. 1069. 



On rocks and stones near low-water mark, and at a greater depth. An- 

 nual. Producing fruit in winter. — Root creeping, fibrous. Frond at first 

 a simple, oblong or lanceolate leaf, 2 — 4 inches long, serrate or jagged at 

 the margins, afterwards, from the elongation of the cilia into branches, 

 deeply pinnatifid or lobed, the lobes simple or forked, ciliate or foliiferous 

 at the margins and over the surface, narrowed at base, acute at the apex, 

 very variable in breadth. Substance thick and cartilaginous, somewhat 

 rigid. Colour a full red, generally becoming darker in drying. Tubercles 

 spherical, on the cilia ; tetraspores transversely zoned, forming cloudy 

 spots on various parts of the surface. 



