CHORDA. 31 



few inches to several feet in length, slender; frond 2 — 12 feet long and 

 4 — 16 inches wide, flat, or waved and curled at the margin. Substance 

 equally variable ; sometimes leathery or cartilaginous, sometimes delicate 

 and memhranaceous. Colour a deep olive green inclining to brown. 



4. L. Phyllitis, Stack.; stem somewhat flattened, filiform, 

 expanding into a delicately membranaceons, flat, linear-lan- 

 ceolate, nndivided frond. Grev. Alg. Brit. p. 34 ; Hook. Br. 

 Fl. '\\.p. 272; E. Bot. t. 1331; Harv. Phyc. Brit. t. cxcii. 



Between tide-marks, growing either on stones or on the stems of the 

 larger Alga. Annual ? Turner ; Biennial ? Greville. Not uncommon. — 

 T own that I share the doubts entertained by my friends Dr. Greville and 

 Mrs. Griffiths, regarding the claim of this beautiful plant to rank as a spe- 

 cies distinct from L. saccharina. The more lanceolate form, delicate sub- 

 stance, and pale yellowish green colour, constitute the chief marks of 

 distinction. Stem 1—2 inches high; frond 8 inches to 3 feet or more in 

 length, and 1 — 6 inches in width. 



5. L. fascia, Miill. ; stem very short, setaceous, gradually 

 expanding into a membranaceous, broadly oblong, wedge- 

 shaped, lanceolate, or linear frond. Ag. Syst. p. 273 ; TVyatt, 

 Alg. Danm. No. 157; Harv. Phyc. Brit. t. xlv. L. clebilis, 

 Ag. Grev. Crypt, t. 277; Alg. t. 5. 



In the sea, on sand-covered rocks. Annual? — Root a minute disk. 

 Stem setaceous, 1—6 lines high, compressed, iusensiblj^ passing into the 

 frond. Frond 4 — 12 inches long or more, and from 2 lines to an inch in 

 breadth, either ovate or cuueate, and often much attenuated at base, some- 

 times tapering at the apex to an acute point, but oftener blunt and some- 

 what truncate, of a delicate membranous substance and olivaceous colour. 



III. Chorda. Stack. [Plate 3, B.] 



Root scutate. Frond simple, cylindrical, tubular; its ca- 

 vity divided by transverse, membranous septa, into separate 

 chambers. Fructijication : * a stratum of obconical spores, 

 much attenuated at the base, covering the whole external 

 surface of the frond. Among these are found elliptical an- 

 theridia. Name, chorda, a cord. 



1. C. JHum, L. ; frond cartilaginous, lubricous, clothed 

 with pellucid hairs, filiform, very long, tapering to each ex- 

 tremity, not constricted at the dissepiments. Grev. Alg. Brit, 

 p. 47, t. 7; Hook. Br. Fl. ii. p. 276; TVyatt, Alg. Danm. 

 No. 159; E. Bot. t. 2487; Harv. Phyc. Brit. t. cvii. /3. to- 



* What are here called spores are by J. Agardh considered as parane- 

 mata, and what are here termed antheridia are the spores of that author. 

 Which is the correct view ? 



