30 LAMINARIA. 



segments. Grev. Alg. Brit, p. 27, t. 5 ; Hook. Br. Fl. ii. p. 

 271; E. Bot. t. 2274; Wyatt, Alg. Danm. No. 166; Harv. 

 Phyc. Brit. t. ccxxiii. 



Bocks in the sea, in deep water, common. Perennial. Root consisting 

 of numerous, rigid, woody fibres, 2 3 inches long. Stem 1 6 feet high, 

 solid, very tough, expanding into a flat frond, 15 feet long and 13 feet 

 wide, which is deeply cleft from the apex into an uncertain number of strap- 

 shaped segments. The power of reproducing its frond, noticed by Turner 

 and Greville in L. digitata, has been observed by Mrs. Griffiths (to whom 

 I am indebted for a beautiful series of specimens) to exist also in L. sac- 

 charina and bulbosa .- it may therefore, perhaps, be considered characteristic 

 of the mode of growth in the genuine Laminarieas. It exists in individuals 

 of all ages. Some of Mrs. Griffiths' specimens of L. digitata exhibiting 

 the new frond, are not more than four inches high, and she has traced the 

 process upwards to plants of large size. The new frond at first appears 

 like a roundish expansion between the base of the old frond and the apex 

 of the stem : this gradually enlarges, becoming of an oval form, and in 

 large specimens is frequently cleft into segments long before the apex is 

 free from the base of the old lamina ; thus proving that the splitting of the 

 frond in this species does not arise from the fortuitous action of the waves, 

 but from an inherent principle of growth. Fig. 2, in our plate, represents 

 a young, growing beneath an old, frond. 



2. L. bulbosa, Huds. ; stem flat, with a waved margin, 

 once twisted at the base, rising from a roundish, hollow, rough, 

 bulbous root ; frond oblong, deeply cleft into many linear 

 segments. Grev. Alg. Brit. p. 29 ; Hook. Br. Fl. ii. p. 271 ; 

 E. Bot. t. 1760 ; Wyatt, Alg. Danm. No. 4, (young plant) ; 

 Harv. Phyc. Brit. t. ccxli. 



On rocky shores, mostly in deep water, frequent. Perennial. Young 

 plant with an oblong, undivided, or slightly cleft frond, 4 12 inches long 

 and 2 3 wide, with a filiform stem about an inch long, furnished with a 

 swelling or dilatation in the centre, and springing from several clasping 

 fibres. As the plant increases in size the stem becomes more and more 

 expanded, and finally waved at the margin, and what was at first a mere 

 knot-like expansion results in a large, bulbous, hollow body, which throws 

 out from its surface stout roots, and becomes the main support of the full- 

 grown frond. This bulb, in a specimen measured by Mrs. Griffiths from 

 deep water in Torbay, was a foot in diameter, and supported a frond which, 

 when spread out on the ground, formed a circle of at least 12 feet in 

 diameter. Common specimens are about half these dimensions. 



3. L. saccharina, L. ; stem cylindrical, filiform, expanding 

 into a cartilaginous or submembranaceous, lanceolate, undi- 

 vided frond. Grev. Alg. Brit. p. 31 ; Hook. Br. Fl. ii. p. 272 ; 

 E. Bot. t. 1376; Wyatt, Alg. Danm. No. 54. /3. latifolia ; 

 frond very broad, ovate-elliptical, submembranaceous. L. la- 

 tifolia, Ag. 



On rocks between tide-marks. Perennial. Very common. /3. in deep 

 water. Root consisting of numerous clasping fibres ; stem varying from a 



