Alga, by W. H. Harvey.] FLORA OF TASMANIA. 321 
tribus cellularum constituta; stratum medullare e filis articulatis longitudinalibus anastomosantibus laxe 
intertextis, intermedium cellulis rotundis majusculis pluriseriatis, cor/ica/e cellulis minimis verticalibus 
formatum.  Cystocarpia fronde immersa, inter fila strati intermedii suspensa, reticulo filorum velata, 
carpostomio demum aperta, fila sporifera a placenta centrali emissa continentia ; spore subrotunde, 
seriate. 
l. Areschougia Laurencia (Harv. Le p. 554).— Thamnocarpus? Laurencia, Hook. fil. et Harv. 
Lond. Journ. Bot. vi. p. 409. 
Has. Georgetown, abundant. Southport, C. Stuart. 
Disrris. West and south coasts of Australia. 
This plant has the habit of a Rkabdonia, but is more firm in texture, and essentially differs in structure by 
having a central articulated filament or axis, of larger diameter than that of the longitudinal filaments composing 
the medullary stratum. 
2. Areschougia Stuartii (Harv.); fronde plano-compressa dense ramosa decomposito-pinnata, 
pinnis basi et apice angustatis, pinnulis fere lanceolatis utrinque acutis erecto-patentibus cystocarpia im- 
mersa gerentibus. 
— Hae. Southport, C. Stuart. 
Frond distichously much branched in a subpinnate manner, and repeatedly compound, 3-6 inches long, and as 
much in the expansion of the branches; the branches and pinnze close together, erecto-patent, narrow-linear, nearly 
` flat, with an evident immersed costa tapering to the base and apex, the lesser ones with an acute point, and nearly 
lanceolate in form. The lower part of the stem and larger branches is thickened. Colour a bright-red, becoming 
scarlet in fresh-water.  Cysfocarps minute, immersed in the substance of the lanceolate leaves, one or two in each 
lamina. The medullary stratum of the frond is very lax.— Nearly related to 4. australis, but narrower, more 
densely branched, with a much laxer internal structure, the filaments composing the medullary stratum being few, 
and standing far apart from each other. It has more the habit of 4. conferta, but its structure is even more diffe- 
rent. From all forms of 4. Laurencia it may be known by its flatness, 
Gen. LXXXVIII. RHABDONIA, Harv. 
(Harv. in Lond. Journ. Bot. vi. p. 408. Kütz. Sp. Alg. 723. J. Ag. Sp. Alg. ii. p. 353.) 
1. Rhabdonia coccinea (Harv. Lond. Journ. Bot. vi. p. 408; Kütz. Sp. Alg. p. 723; J. Ag. Sp. 
Alg. ii. p. 354; Harv. Phyc. Austr. t. 54).— Chrysymenia coccinea, Harv. Lond. Journ. Bot. iii. 
p. 448. 
Has. Georgetown, Gunn. 
Disrris. Port Phillip. 
2. Rhabdonia nigrescens (Hook. fil. et Harv. Lond. Journ. Bot. vi. p. 409; J. Ag. Sp. Alg. ii. 
p. 354). 
Has. Georgetown, Gunn. 
Drsrmrs. South coast of New Holland. 
I fear I have led my friend Sonder into error by distributing to him a wrongly marked specimen of one or 
other of these nearly allied, but, as I still think, distinct species. C. coccinea is of a much softer substance, and 
becomes of a brilliant crimson colour when steeped in fresh-water. C. nigrescens is rigid, very imperfectly adheres 
to paper, and is always of a dull, dark, brownish-red colour, even after exposure to fresh-water. " have collected 
both species abundantly, and can always distinguish them when growing. C. coccinea has a more evident stem, and 
tts branching is somewhat pyramidal: C. nigrescens is bushy, branched from the base. 
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