I :
2. D UitviLLÆA Ilmveiji, Hook. fil.; radice e fibris crassis demum anastomosantibiis constante, stipite
perbrcn valido compresso in laminara subsolidam coriaceam apice laciniatimi gradatim dUatato. - Nobis in
Loni. Joum. Bot. vol. iv. p. 249. Himantlialia D’UrviUæi, Bon/ ? in Buperrey Voy. Bot. p. 135. (Tab
CLXV, CLXVI.) J w y J i t ■
H ab. Hermite Island, Cape Horn, and tlie Falkland Islands ; abmidant.
Rttius fibrosus, fibns crassis, inter se intricatis, demain anastomosantibiis, discum callnmve pertusum 2-4 unc.
diametro effloientibus. Stipes 3-4-uuciaRs, i - | unc. diametro, valde compressus, bi laminam forma variara
gradatim düatatus. ^ Umim 4-8-pedalis, supra medium 1-2 ped. lata, plerumque late lanceolata, basi angustata,
apioem versus m lacinias plures Uneari-elongatas Hgulatas abbreviatasve acutas trimcatasve fissa, siccitate atro-fusca
V, subpicea, opaca, dura, subfragüis, Uneis snperficiaHbus striata, v, subretioidata, e conceptaculis prominulis mamUlosa ;
madore olivaceo-brimnea, coriacea v. flaccida, plana, lævis, intus soHda, l - I lin. crassa. Conceptaeula spliærica,’
per totam frondem sparsa, poro inconspicuo pertusa, fllis articidatis sporisque basifixis repleta. Sporæ ut in B. utili,
varie quaternatim divisæ, limbo hyalino cinctæ.
Always considerably sinaRcr than the B. utilis, of a much thinner textm-e, and readUy distinguishable by its
fibrous root. I have never observed the ii-ond of even the largest state of this species to be flUed with tbose
elongated transverse cells whicli distinguish the former.
The structure of the fi-onds is seen to consist, on a transverse section, of a dense narrow layer of cortical substance,
wlucli gi-aduaRy becomes more open inwai-ds, and there breaks up into parallel lamelloe projecting towards tlio
centre of the frond. Tliese are less densely packed inwai-ds, and are united at right angles by similar very
sbort plates, together forming a loose cellular tissue, wbose waUs ai-e thickened at the angles ; wliich, again, nt tho
very centre of the frond, ai-e gi-adually resolved into a mass of slender, short, waved filaments, free or anastomosin»-
and floating in a gelatine. °
The affinity of the Laminaria potatorum is probably with tbis genus ; it is described, by M. Kiitzing, under the
generic name oí Sarcophgcus (Phycologia, p. 892). I have examined a vei-y smaU fragment ofthe plant, and find
the spores to bo contained in cysts, altogether like those of D' Urvillæa and Xiplioplura.
PLA-tEs CLXV, CLXVI.—1, transverse slice of frond ; 2, vertical section of ditto ; 8, spores and ¡mtheridia ;
4, spores :—highly magnijied.
2. SCYTOTHALIA, Grev.
1. S c y t o th a l ia Jacquinotii, Mont., in Vog. a% Pole Sud, Bot. Crgpl. p. 8 6 . t. 5.
H ab. Gratiam’s Land; lat. 63° S., floating in the ocean, Br. Ig/all. Deception Island, New South
Shetlands; Mr. Webster.
An accurate description of this uoble sea-weed is given by its discoverer, Mr, Webster, R.N., iu the Appendix to
tbe Narrative of Capt. Foster’s Voyage ; though nothing was known of the species, botanicaUy, until specimens were
received by Dr. Montague, from the Herbarium of tbe French South Polar Expedition, coUected within a very few miles
of the spot where it was again seen by tbe Antarctic Expedition, and obtained by our indefatigable friend. Dr. Lyall.
The existence of this sea-weed on the Icy shores of an Antarctic land, in the longitude of Cape Horn, is a most
singular and anomalous fact ; for I beUeve it to be the only species of the tribe Cystoseirem, which inhabits the colder
01- Antarctic seas of South America ; tliough many abound in similar temperate latitudes of New Zealand, Lord
Auckland s gi-oup. New HoUand, and Tasmania. We have thus, under the most rigorous skies, tbe representative of
a group, the total absence of ivhose other species in warmer seas of tbe same longitude, was supposed to be owing
to a low degree of temperatm-e being destructive to its life. The said group of Oyslosàreoe is not here represented by a
species 111 any way indicative of its habitat being far removed I'roiu its congeners, or of its locality being uncongenial,
Falklands, etc] FLOBA ANTARCTICA. 457
except by one of its own aspect ; for its nearest and. indeed, very near ally, is a native of New HoUand ; ivhUst m
size, luxuriance and beauty of growth, the present surpasses not only aU other species of the genns, but almost the
whole of the group Cystoseirem.
We are accustomed to regard the ocean as so ever-active and powerful an agent in facilitating migration, and
its imifoi-m temperatiu-e is so conducive to the general diflusion of species, that it seems almost wonderful that Jlgm
should have limits to their distribution, especially in waters wbicb gird the globe on the same parallel of latitude,
and whose unchecked swells and currents literally extend over every degree of longitude. The remarkable increase in
temperature of the tropical over the polar seas of the Atlantic may, and probably alone does, check tbe progi-ess of
the Macrocystis in its com-se from Cape Horn to the Equator in that ocean, for, as I sliaU afterwards show, the same
sea-weed can float with the colder cm-rents of the Pacific from the same Cape to Belu-ing's Straits ; but no such
obstacle prevents tbe fuUest interchange of Cystoseirem between New Zealand and tbe temperate seas of Soutli
America. It. however, is the fact, that wliilst this gi-oup literally abounds in certain latitudes and longitudes,
wbioh are tbose of New HoUand and the West Pacific, they are nearly absent from analogous positions in the
longitude of South America.
Throughout aU latitudes the two tribes Jucoidem and Cystoseirem form that prevailing marine vegetation to which
the name sea-weed is commonly applied ; and the different genera so far an-ange themselves within geographical limits
as to present, with such few exceptions as the Scytothalia Jacquinotii, a most hai-monious assemblage. Thus,
in the opposite colder and frigid zones the waters are iiiliabited by certain genera of Fucoidem whicb are in a great
measure representatives of one another ; as, in
the north cool zone
Fucus proper, and ai-e represented in analogous B' Urvillea, and ' ..|
Himanthalia, southern zones, by Sarcofhycus, Kütz. ythe
None of these genera approach the tropics, for the Fticoidece abound towards the poles, and there attain their greatest
bulk, diminishing rapidly towards the Equator, aud ceasing some degi-ees from the Line itself. The representatives
of the Cgstoseirea in the higher latitudes of the opposite hemisphere, are equally appropriate with those of
Fucoidece, for we have in
north cool zone
Oxjstoseira, and i represented in the
Halidi-ys, j south cool zone, by
Blossevillea, and
Scytothalia ;
whilst the immense genus Sargassxm flnds its maximum in lower latitudes, and under the Equator itself.
Such arc the salient featui-es of the distribution of these tribes, which are not influenced by the minor divisions,
chiefly local assemblages of small genera, affecting exclusively certain coasts or bays.
3 . LESSONIA, Bory.
I . L e s s o n ia fuscescens, Lory, in Buperrey Voy. Bot. Crypt, p. 7 5 . t. 2. f. 2. et t. 3. Post, et Ruppr.
Illust. Alg. p. 2. t. 3 et p. 4 . t. 3 9 . f. 1 4 - 1 8 . D Urville, in Mern. Soc. Liim. Paris, vol.iv.
p. 5 9 4 . (Tab. CLXYII., CLXVIII. A., and Tab . CLXXI. B.)
H ab . Hermite Island, Cape Horn, and Ealkland Islands; most abimdant, always far beyond low-water
mark. Christmas Hai'bom*, Kerguelen’s Land; rare
Tlic fructification of the species of Lessonia occm-s, as in Macrocystis, upon the surface of the fronds, and
there forms large patches. In the present species the sori ai-e situated beyond the middle of the leaf, they
are oblong and neai-ly as broad as the lamina, of which they carry away the upper part when decaying, causing
their broad apices to be two-horned. In none of oiu- specimeus is the poiut perfect, all the spores we have seen
bemg situated ou the edges of the sorus, which has itself fallen away from the frond. The air-cells are less
numerous, and the spores are sniaUer, shorter, more densely packed than in the following species, and covered
5 N
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