i l , / / , X / J l .
P l a t e XLIX.
DESMARESTIA ACULEATA, Lamouf.
Gen. C h a e . Frond linear, either ffliform, compressed, or flat, distichously
branched, cellular, traversed by an internal, single-tubed, jointed filament
; producing, when young, marginal tu fts of byssoid, branching
fibres. Fructification unknown. D e s m a e e s t i a {Lamour.)— in honour
o i A . G. B em a re s t, a celebrated F rench naturalist.
D e s m a r e s t i a aculcata ; stem short, cylindrical, bearing numerous slender,
elongate, flattish, irregularly bi-tri-pinnate branches ; pinnse and pin-
nulæ alternate, tapering a t th e base, filiform, either fringed with opposite
tufts of b rig h t green fibres, or margined with erect, awl-shaped,
alternate, distichous spines.
D e sm .a e e s t ia a c u le a ta , Lam. Ess. p . 3 5 . Grec. Alg. Brit. p . 8 8 . t. 5. f. 3, 3.
Hook. Br. El. vol.ii. p . 3 7 3 . Harv.in Mack. El. Hih. p a r t 3. p . 1 7 2 . Wyatt,
Alg.Banm. 110.133. Hare.Man. p. 23. Endl. 3rd Suppl. p. 23. Külz.
Phyc. Gm. p . 3 4 3 . t . 2 6 . f. 1.
D e sm ia acu le a ta , Lyngb. Hyd. Ban. p . 3 4 . t. 4 4 . B . 1
Hook.
S p o r o c h n u s aculeatus, Ag. Sp. Alg. vol. i. p. 151. Ag. Syst. p. 259.
El. Scot. part 2. p. 96. Grev. El. Edin. p. 287.
Fuous aculeatus, lAnn. Sp. PI. p. 1632. Huds. El. .
<ig. p. 585.
Scot. p. 924. El. Ban. t. 355. Stack. Ner. Brit.
. 24. t. 8.
vol. ii. p. 262. Turn. Hist. 1 .187.
F u cu s muscoides, Linn. Sp. PI. p. 1630. Httds.El. Ang. p. 590.
H ab. On rocks and stones in th e sea, near low-water mark, and a ^
Light. El.
Turn. Syn.
depth. Perennial. Common on th e shores of th e British Islands.
G e o g e . D i s t e . Atlantic shores of Europe, from North Cape to Spain. Shores
of Piedmont, Allioni (but omitted by J. Agardh in his Alg. Medit.).
D e s c e . Boot a hard disc. Eronds 1-3 , to 6 feet in length, undivided, or
hraiiching from a short distance above tbe base, preserving throughout a
nearly equal breadth of half a hue, compressed, more or less angularly
flexuous, bearing along their whole length alternate lateral branches, the
lower of which are longest, the rest graduaUy shorter upwards. Lower
branches repeatedly compound, bearing one, two, or tliree sets of distichous,
alternate, erect or erecto-patent lateral branches ; upper ones gradually less
aud less compound, and those near the apex quite simple. Occasionally
two branches spring from the same point, at the same side of the stem,;
and more rarely, two of the lesser branches are found opposite to each other
In an early stage of growth aU the branches are clothed, at intervals of
about a line, with opposite pencUs of finely divided, repeatedly pinnate,
byssoid, articulated fibres of a beautiful yeUow-green colour, which apparently
originate in the jointed thread which runs through the centre of the
frond. These fibres soon fall away, leaving the stems and branches naked,
and then alternate, subulate spines are developed at intervals of two to four