98 LAURENCIA. 



1. L. pinnatifida, Gm. ; frond compressed, cartilaginous, 

 bi-tripinnatifid, divisions alternate, the ultimate ones obtuse, 

 simple or lobed. Grev. Alg. Brit. p. 108, t. 14 ; Hook. Br. 

 Fl. ii. p- 296; Wyatt, Alg. Damn. No. 113; Harv. Phyc. 

 Brit. t. Iv. Fucus pinnatifidus, E. Bot. t. 1202. 0. Os- 

 munda; frond flat, generally undivided, ramuli short and 

 multifid. Hook. 1. c. y. tenuissima ; frond flat, ramuli very 

 thin and much branched, the branches divaricated. Hook. I. c. 



On rocks, between tide-marks. Annual. June to September, o. and /8. 

 very common : y. Devon and Cornwall, Mrs. Griffiths. Fronds tufted, 

 1 12 inches high, compressed or subcylindrical, from half a line to 2 lines 

 in breadth, alternately branched, the branches pinnatifid or bipinnatifid. 

 Substance cartilaginous. Colour varying from a yellowish green to a dull 

 purple or brownish red. Capsules broadly ovate, placed on the smaller 

 branches ; tetraspores imbedded in the ramuli. An extremely variable plant 

 in size and general appearance. The taste is often hot and biting, whence 

 it has obtained the name of Pepper-dulse in Scotland. 



2. L. caspitosa, Lamour. ; frond cylindrical or sub-com- 

 pressed, narrow, repeatedly pinnate, pyramidal ; main branches 

 often opposite, erecto-patent ; ramuli irregularly scattered, 

 distichous or spreading on all sides, often crowded, erect, 

 slightly tapering to the base, truncate. Mont, in PL Canar. 

 p. 154; Harv. Phyc. Brit. t. cclxxxvi. L. hybrida, Lenorm. 

 L. pinnatifida, y. angusta, Hook. Br. Fl. ; Wyatt, Alg. Damn. 

 No. 162. 



On stones, &c., within tide-marks. Annual. Summer. Common. 

 Fronds 2 8 inches high, as thick as small twine, cylindrical or the main 

 divisions slightly compressed, somewhat bare below, much branched above, 

 with a pyramidal outline. Branches once or twice pinnate, erect or erecto- 

 patent, irregularly set. Ramuli very irregular, often much crowded, sim- 

 ple or multifid, terete, tapering to the base and truncate. Colour either a 

 very dark lurid purple, or (under the effects of sunlight) greenish yellow. 

 Almost intermediate between the preceding and following; more cylin- 

 drical and narrower than L. pinna.tifi.da ; and very different in colour and 

 in general habit from L. obtusa. 



3. L. obtusa, Huds. ; frond cylindrical, filiform, twice or 

 thrice pinnate ; ramuli mostly opposite, short, patent, wedge- 

 shaped, obtuse. Grev. Ala. Brit. p. Ill ; Hook. Br. Fl. ii. 

 p. 296; Wyatt, Alg. Damn. No. 21 ; Harv. Phyc. Brit. t. 

 cxlviii. Fucus obtusus, E. Bot.t. 1201. 



On the larger Algae. Annual. Summer and autumn. Shores of Eng- 

 land and Ireland, frequent. Bare ill Scotland. Root somewhat fibrous. 

 Fronds generally tufted, 3 6 inches long, about half a line in diameter, 

 cylindrical, filiform, repeatedly branched in a pinnate manner, the branches 

 and ramuli mostly opposite, the latter 1 or 2 lines long, obtuse or truncate, 

 somewhat narrowed at base, or nearly cylindrical. Substance tender and 



