Ser. RHODOSPERME. Fam. Chondriee. 
Prats CCLXXXVI. 
LAURENCIA CAISPITOSA, Lamour. 
Gen. Cuar. Frond cylindrical or compressed, linear, pinnately branched, 
the apices obtuse; structure cellular, solid. Fructification of two 
kinds, on distinct individuals; 1, ovate capsules (ceramidia), fur- 
nished with a terminal pore, containing a tuft of pear-shaped spores ; 
2, triparted ¢etraspores, imbedded in the ramuli. Lavurencta 
(Lamour.),—in honour of M. de la Laurencie, a French naturalist. 
Lavrenota cespitosa; frond cylindrical or subcompressed, narrow, re- 
peatedly 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. 
LAvRENCIA cespitosa, Lamour. Ess. p.43. Mont. Pl. Crypt. Canar. p. 154. 
Harv. Man, ed. 2. p. 98. 
Lavurencia hybrida, Lenorm. in Dub. Bot. Gall. p.951. Harv. Phyc. Br. 
vol. i. p. xiii. 
LavURENCIA pinnatifida, y angusta, Grev. Alg. Brit. p. 109. Hook. Br. Fl. 
vol. ii. p. 296. Harv. Man. p.69. Harv. Phyc. Brit. pl.55. Wyatt, 
Alg. Danm. no. 162. 
Fucus hybridus, D.C. #7. Fr. vol. ii. p. 30. 
Has. On stones and shells, within tide-marks; rarely growing on other 
small Alge. Annual. Summer. Common on the shores of the 
British Islands. 
Groer. Distr. Atlantic shores of Europe. Canary Islands. Southern Ocean. 
Descr. Root accompanied by creeping fibres. Fronds densely tufted, from two 
to six inches in length, about half a line in diameter, of nearly equal 
breadth throughout, cylindrical, or very slightly compressed, having a per- 
current undivided stem, set with numerous, alternate, or rarely opposite, 
erecto-patent branches, the lowermost of which are longest, the upper gra- 
dually shorter, so that the whole plant has a pyramidal or conical outline. 
Branches repeatedly pinnated, their divisions naked at base, pinnated for 
three-fourths of their length, all the divisions very erect, blunt, or truncate, 
each ultimate ramulus frequently bi-trifid at the point. Ceramidia. . . ? 
Tetraspores confined to the apices of the ramuli, numerous, tripartite. 
Colour, when the plant grows under favourable circumstances, a very dark, 
lurid purple: when more exposed to the light, variously greenish or yel- 
lowish. Swéstance cartilaginous, becoming softer in fresh water, and then, 
under pressure, strongly adhering to paper. 
nnn 
I offer this species with some hesitation, as it has hitherto 
been generally considered by British authors a variety of Z. pin- 
N 2 
