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lif V.
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Hab. Everywhere common in ditches and rivulets.
“ In a stream below Penmaen Pool, near Dolgelly; and
within the influence of the tides, I have gathered a tufted
state of this species of a bluish colour, not unlike the iridescent
tints of Cgstoseira ericoides. I t was growing with Ectocarpus
littoralis. I have also for several years observed it in the
same state in a cave by the sea side at P enzance; in both
instances it afterwards became brownish, and finally green.”
— Ralfs.
I t is on this species that the inflated vesicles usually occur,
and which formerly induced me to refer it to a section of the
genus Vesiculifera,
4. Meloseira ochracea Ralfs.
Char. “ Frustules very slender, convex at each end, ovate, not
striated, ferruginous. Filaments often connected together
in a suhramose manner.”
Gallionella ferruginea Ehr., Die Infns. p. 169. t. 10. fig. 8.,
and t. 21. fig. 3. Conf. ochracea Dillw., t. 62. Oscillatoria
ochracea Grev., Flor. Edin. p. 304.; Harv. Br.
Alg. p. 167. M. ochracea Ealfs, in Annals, vol. xii.
p. 35.
Hab. Pools and slow streams in boggy soils.
“ This plant occurs in delicate ochraceous or ferruginous
masses, falling into powder on the slightest touch. The filaments
are so slender, and the joints so obscure, that I have
been unable to determine the form of the frustules, and have
therefore taken the specific character from E h ren h erg : I am
also unable to ascertain whether the joints are marked by any
central line. Having received from Mr. Dillwyn a specimen
of his Conf. ochracea, which I am able confidently to refer to
this species, I have restored the original specific name.
Ehrenherg is no doubt correct in placing the plant in this
genus, as the filaments are cylindrical and silicious.
“ When submitted to a red heat it acquires a reddish tinge.
which circumstance, together with the colour and slender filaments,
will distinguish it from all other species.” —Ralfs.
67. A C H N A N T H E S Bory.
Char. Frond stipitate, standard-shaped, composed o f few
frustules, which are longer than broad, curved, and have a
punctum at the centre o f the inferior margin.
Derivation. From a^vy, the fro th o f the ocean, and av6os,
a flower.
The stipes is attached not to the centre of the lower frus-
tulc but to one of its angles, and this position of it gives rise
to the resemblance of each entire frond to a standard.
1. A chnanthes minutissima Kutz.
Plate C. Fig. 4.
Char. Frustules small, slender ; in lateral view obtuse, and
apparently without striæ. Stipes very short.
Kiitz. Syn. Diatom, p. 578. f. 54. ; Ehr. Infus. p. 228.
pl. X X . f. 5. ; Ilalfs, in Annals, vol. xiii. p. 492. pl. xiv.
fig. 2. ; Jenner, in Flor. of Tunbridge Wells, p. 200.
Hab. Parasitic on other Algæ, Newtimber, Sussex : Mr.
Borrer. Several places in Sussex, &c. ; Mr. Jenner.
Cheshunt : A. H . H. Oswestry : Rev. T. Salwey. P en zance
: Mr. Ralfs. Bristol : Mr. Thwaites.
The fronds are very minute, and rarely consist of more than
two frustules.
“ Before I had the opportunity through Mr. Borrer’s kindness
of comparing our plant with the specimen in Kiitzing’s
‘ Alg. Aq. Dulc.’ I considered it a variety of the following
species; and I am still uncertain whether they should be
separated, although the plant above described is undoubtedly
Kiitzing’s Achnanthes minutissima.” — Ralfs.
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