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any species except the following one. In Britain, its full length is
about three inches ; but a specimen in my possession, gathered by Miss
Hutchins in Ireland, measures about eight inches. I have seen its
breadth equal to neai- three lines, and, on the other hand, hardly exceeding
half aline. The younger leaves of some specimens collected
in Bute, are still narrower. In some Devonshire individuals, found
by Mrs Griffiths, the substance is firmer, and the reticulation less conspicuous,
but they do not otherwise differ.
If car efully examined under the microscope, the frond will be found
to be transversely veined, as in the following species, but, in this instance,
the oblong cellules which form the vein, are arranged in a single
undivided line, and are much less conspicuous. I have never, liowever,
found them absent.
5. D e l e s s e r ia r u s c i f o l ia .
Frond with leaves proliferous from the midrib, leaves linear-oblong,
abruptly attenuated at their origin, the youngest ones always rounded
at the apex, ternate granules forming two linear parallel spots towards
the end of the leaves.
Delesseria ruscifolia, L am o u r . E s s a i, p . 124. Ag . S p . A lg . v . 1. p . i ; 4 . S y s t. A lg . p . 249.
Wm-mskioldia ruscifolia, S p r e n g . S p . P I. v . 4. p . 331,
Fucus ruscifolius. T u r n , in L in n . T r a n s , v . 6. p . 127. t. 8. f. 1. S y n . F u c . p . 11. H is t.
F u c . t . 15. S m . E n g . B o t. t . 1395.
H a b . In the sea, attached to rocks aud other Algce. Annual.
May to September. Yarmouth, Turner. Coast of Suffolk, at Corton
and Gunton, Mrs Fowler. Bognor, Mr De Luc. Budleigh, Sidmouth,
Torquay, Ilfiacombe, and other places on the Devonshire coast,
Mrs Griffiths. Fxmouth.
Root a minute disk. Fronds several from the same base, one to
three inches in length, and two or three lines in widtli, at first entire
and ovate-oblong; afterwards producing other leaves, of an oblong
or linear-oblong form from the midrib, in a proliferous manner;
and in this way the original frond becomes tliree or four times divided,
the youngest leaves being always roundish or obovate, and
very obtuse. The margin is throughout entire, fiattish, or waved.
The space between the midrib and margin is traversed by oblique,
parallel, white, pellucid, branched veins, composed of a single row of
elongated cellules. Fructification : 1. spherical capsules sessile on
the midrib of the younger leaves, filled with roundish seeds: 2. linear
sori or spots a line or more in length, on each side of the midrib on
distinct plants, composed of ternate granules.
Substance thin and membranaceous, but more elastic than the preceding,
adhering to paper in drying. Colour fine rose pink.
The present and the preceding species, it will be at once perceived,
are very much alike in many points, and they were confused together,
till Mr Turner separated them, in a paper published in Linnean Transactions.
Some of the varieties, however, still come so near to one
another, that it is very difficult to pronounce upon them, unless some
prominent character be kept in view. The most decided one is perhaps
the form of the youngest leaves, which Mr Turner says is constant,
and I have found no reason to differ from that close observer.
The transverse veins certainly exist in both species, but are far more
visible in D. ruscifolia. In this species, also, the reticulation is mucli
smaller, and the cellules of a rounder figure than in D. Hypoglossum.
The present plant is a very beautiful one, and by no means so frequent
as the last species. I am not aware that it has heen found in
Scotland or Ireland.
G e n u s XXV. NITOPHYLLUM,* Grev. Tab. XII.
G e n . C h a r . Frond plane, delicately membranaceous, rose-
coloured, reticulated, wholly without veins, or very slight
vague ones towards the base. Fructification, hemisplieri-
cal capsules imbedded in the substance of the frond, and
ternate granules forming distinct scattered spots.
Obs. The plants forming this genus are removed from all other Flor
i d e t e by their extreme delicacy and tenuity, their beautifully reticulated
structure, their transpai-ency, and peculiar fructification, the ternate
granules being always collected into defined sori or little spots, scattered
• H a v in g j u s t re c e iv e d t h e t h i r d f a s c ic u lu s o f t h e b o ta n ic a l p a r t o f D u p e r r e y ’s V o y a g e ro u n d t h e
W o r ld , 1 p e r c e iv e t h a t B o ry d e S t V in c e n t h a s a d o p te d t h e g e n e r ic n am e o f Dawsonia f o r th i s
g r o u p ; a n am e s u g g e s te d b y P a l i s o t d e B e a u v o is , a s a p r o p e r o n e fo r a g e n u s o f Alga, b u t n e i t h e r '
d eB n e d n o r a p p l i e d b y t h a t n a tu r a l i s t . L am o u r o u x , in d e e d , to o k i t u p , b u t in so in d e f in ite a
m a n n e r , t h a t h is sp e c ie s a r e r e f e r r e d b y a ll a u th o r s to tw o o r th r e e o th e r g e n e r a . U n d e r s u c h
c ir c um s ta n c e s w a s M r R . B row n 's g e n u s o f M o s s e s , Dawsonia, e s ta b lis h e d , d e d ic a te d t o t h e s am e
e x c e lle n t m a n M r D aw so n T u r n e r , f o u n d e d u p o n o n e o f th e m o s t s in g u la r o f p l a n t s , w ith n o
am b ig u i ty o f c h a r a c te r . T h i s .sure ly is t h e Dawsonia t h a t w ill r em a in , a n d c o n n e c t t h e n am e s o f
T u r n e r a n d B row ii in t h e a n n a ls o f s c ien c e .
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