GELIDIUM. 137 



1. Grateloupia, Ag. [Plate 17, A.] 



Frond flat, pinnate, membranaceous, flexible, solid, com- 

 posed of densely interwoven, anastomosing, branching fila- 

 ments ; those of the periphery moniliform, short, and very 

 strongly compacted together. Fructijiction: 1, globular 

 masses of spores {flavellidia) immersed beneath the periphe- 

 ric stratum, and communicating with the surface by a pore ; 

 '2, cruciate tetraspores, vertically placed among the filaments 

 of the periphery, in subdefined sori. — Named in honour of 

 Dr. Graieloup, a French algologist. 



1. G. Jilicina, Wulf. ; frond linear, attenuated at each 

 extremity, irregularly once or twice pinnated with branches 

 contracted at the base, and tapering to the apex. Grev. Alg. 

 Brit. p. 151, /. 16; Hook. Br. Fl.n.p. 306; IVijatt, Alg. 

 Damn. No. 123; Harv. Phyc. Brit. t. c. Fucus Jilicinus, 

 Turn. Hist. t. 150. 



On rocks and stones at half-tide level, freqnentlj where a small stream- 

 let runs into the sea ; very rare. Perennial. October to December. 

 Sidmouth and Ilfracombe, Miss Cutler. Land's End, Mr. Ralfs. Ilfra- 

 combe and Torbay, Mrs. Griffiths. Mount's Bay and Aberystwith, Mr. 

 Ralfs. — Fronds tufted, rising from a minute disk, seldom more than two 

 inches high in British specimens, (exotic ones are often 8 — 10 inches), 

 from half a line to a line in breadth, with an undivided or once forked, 

 flexuous stem, which tapers to the base and apex, naked at base, its upper 

 half, and often its greater length, more or less set with opposite or alter- 

 nate, distichous, flexuous branches or pinnee, which are either simple, or 

 clothed in the upper part with a second series of pinnulse ; all the branches 

 and ramuli linear, attenuated at the apex, and more or less contracted at 

 base. Substance membranaceous, more or less perfectly adhering to paper. 

 Colour a dull, dark purple or greenish, very like that of Dumontia Jilifor- 

 mis. Favellidia minute, immersed in the branches, with a pore ; cruciate 

 tetraspores in the smaller pinnules. This last sort of fruit I find in speci- 

 mens communicated by Mrs. Griffiths, from Ilfracombe and Hagington, 

 October, 1836. 



II. Gelidium, Lamour. [Plate 17, B.] 



Frond linear, compressed, pinnated, corneous, solid ; its 

 axis composed of densely interwoven, longitudinal, tenacious 

 fibres ; the periphery of small, polygonal cells. Fructijica- 

 tion : 1, tubercles [flavellidia) immersed in swollen ramuli, 

 containing a spherical mass of oblong spores ; 2, tetraspores 

 immersed in the ramuli, bipartite or tripartite, — Name, from 

 gela, frost ; whence also gelatine : but none of the species 

 of the restricted genus are gelatinous. 



