D i 7 ti
P l a t e C X L V I IT .
LAURENCIA OBTUSA, Lamour.
G e n . C h a k . Frond cylindrical or compressed, linear, pimiately branched, the
apices obtuse ; structure cellular, solid. Fructification of two kinds,
on distinct individuals; 1, ovate capsules [ceramidia), furnished with
a terminal pore, containing a tu ft of pear-shaped spores; 3, triparted
tetraspores, imbedded in the ramuli. L a u e e n c i a [Lamour.), in
honour of M . de la Laurencie, a French naturfiUst.
L a u e e n c i a oUma-, frond cylindrical, filiform, repeatedly pinnate; branches
patent ; pinnæ and pinnnlæ mostly opposite, th e ultimate pinnules
very short and obtuse, sometimes cruciform.
L a u e e n c ia obtusa, Lamour. Ess. p. 42. Buhy, Bot. Got. p. 951.
B r i t . v .A l l . J. Ay. J ig . Medit. g . \ \ 4 . Endl. 3rd Suppl. g. 43. Mont.
Algier. p. 92. LLook. Br. I I . vol. ii. p. 296. Wyatt, Alg. Banm. no. 21.
H a n . in Mack. I I . Hib. part 3. p. 198. H a n . Man. p. 70.
L a u e e n c ia intricata, Lamx. Ess. p. 43. t. 3. f. 8, 9.
L a u e e n c ia gelatinosa, Lamx, sec. Ag.
L a u e e n c ia lutea, Lamx. sec. Ag.
L a u e e n c ia cyanosperma, Lamx. Ess. p. 43.
C obtusa, Ag. Sp. Alg. vol. i. p. 340. Sy
p. 202. Hook. El. Scot.
h o n d e ia p a r t2 . p. 105. Grev. El. Edin. g. 299. Spr.
Syst. Veg. vol. iv. p. 341.
Kiitz. Phyc. Gen. p. 437.
F ucus obtusus, Huds. El. Ang. p. 586. Turn. Syn. p. 43. Turn. Hist. t. 21.
E. Bot. 1 .1201.
H a b . Parasitical on th e smaller Algai b e tw e e n ^ tide marks. Annual.
Summer. N o t uncommon on th e shores of England and Ireland.
Rare in Scotland. F rith of Forth, B r. Greville. Ardroppan and
Arran, Rev. B . Landsborough.
G e o g e . D i s t e . Dispersed tliroughout the Atlantic and Pacific Oeeans, both
north and south, in temperate and subtropical latitudes. Meditemanean
Sea. Maui-itius.
D esoe. Boot, a small disc, with or without accessory fibres Eronds several
from the same base, forming dense, globose tufts, from three to six inches
louK, C/Vlindrical, of equal diameter throughout, slender, from a quarter to
half a line in diameter, furnished with a simple stem, which is closely set
throughout with very patent or horizontal, often opposite lateral branches,
which diminish in length from the base to the apex, so th a t the whole frond has
a pyramidal outline. Branches subdistichous, or more or less quadritarious,
spirally inserted, repeatedly pinnate ; pinnæ opposite, patent, the lower
ones often short and multifid, the middle ones longest, lanceolate and
s im p l y o r doubly pinnate, the upper gradually shorter to the tip Ultimate
ramuli very short, obtuse, somewhat clavate, simple, or furnished with
G 2