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P l a t e XCII.
PORPHYRA LACINIATA, Ag.
Gen . C h a e . Frond delicately membranaceous, flat, purple. Fructification,
granules, arranged in fours, scattered over the whole frond; also
“ scattered sori of oval spores.” (Ag., Grev.). P o e p h y e a (Ag).—
from n o $ < j> v p o s , purple .
P o e p h y e a laciniata ; frond deeply and irregularly cleft into several broad
segments.
P o e p h y e a laciniata, Ag. Sgst. p. 190. Ag. Ic. Alg. Mar. t. 26, 27. Orev.
Alg. B r i t .-Ç. 1 6 % . Hook. Br. Ml. Yol.ii. p . 3 1 3 . H a r v . i n M a c k . M . H i b .
part 3. p. 341. Harv. Man. p. 169. Wyatt, Alg. Banm. no. 32. Endl.
3rd Suppl. p. 19. Kiitz. Phyc. Gen. p. 383.
P o e p h y e a um b ilic a lis, Kiitz. Phyc. Gm. p . 3 8 3 .
U l v a la c in ia ta , Lightf. El. Scot. p . 9 7 4 . t. 3 3 . Bath, El. Germ. p . 5 8 5 . Ag.
Sp. Alg. v ol. i. p. 4 0 4 .
U l v a umbilicalis, E. Bot. t. 2286. Lyngb. Hyd. Ban. p. 28.
H a b . On marine rocks, within the range of the tide. Annual. Spring to
autumn. Abundant on all our shores.
G e o g r . D i s t e . Throughont the Atlantic Ocean, from the Poeroe Islands to the
Cape of Good Hope.
D e s c r . Boot, a minute disc. Eronds two to eight inches long, clustered together,
expanded, delicately membranaceons, pellucid, very irregularly divided
into several lobes; the point of attachment frequently within the frond,
which is then peltate. Margin wavy, entire or irregularly cut ; apices often
truncate. Under the microscope the whole frond appears to be divided into
squares, in the manner of a tessellated pavement, and within each square
are four purple granules, or spores, which constitute the fructification and
the whole colouring matter of the frond. When not in a state of perfect
fructification the colour is much less bright, tending to a livid olive. Besides
the usual fructification. Dr. Greville describes a second, consisting of “ sori
of smaUer ovate granules scattered without order chiefly towards the margins
of the frond.” These I am not acquainted with. In drying, the colour
becomes much brighter ; but the glossy and delicate fronds do not adhere
closely to paper, and shrink very much.
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This very common plant is found in most parts of the Ocean
throughout the tropics, and exists nearly as far as vegetation
extends towards the poles. It vaj-ies in different places, something
in substance, being thicker or thinner; something in
colour, being sometimes of a bright purple, and sometimes much
tinged with olivaceous green ; and something in form, some indi-
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