Ser. RhodospermejE. Fam. Spkarococcoidea. 



Plate XXV. 



MELANTHALIA OBTUSATA, /. Ag, 



Gen. Char. Frond linear, piano-compressed, dichotomous and fastigiate, 

 coriaceous, solid, densely cellular ; the inner stratum composed ot 

 elongate, angular, colourless cells ; the outer of very minute, coloured, 

 vertically seriated cellules. Fructification : 1, marginal, hemispherical, 

 thick-walled conceptacles, containing, on a central placenta, densely 

 tufted, moniliform spore-threads, at length dissolving into minute 

 spores; 2, tetraspores (?).... ? — Melanthalia {Mont.), from iiekas, 

 black, and daXos, a branch ; because the frond becomes very dark in 

 drying. 



Frons linearis, plano-compressa, dichotomo-fastigiata, coriacea, solida, duplici 

 (v. " subtriplici ") strato composita ; interiore cellulis elongatis ienuibus 

 angulatis hyalinis, exterlore cellulis minutis coloratis densissime verticaliter 

 seriatis constante. Fruct. : l,coccidia marginalia, hemisphcerica, intra peri- 

 car pium crassissimum fla sporifera moniliformia ex placenta centrali egre- 

 dientia in sporasdemum soluta foventia ; 2, ietrasporce (ignotce). 



Melanthalia obtusata ; frond elongate (1-2 feet long), repeatedly dicho- 

 tomous and flabelliform ; segments flattish, two-edged, linear, bluntly 

 truncate; conceptacles marginal, scattered. 



M. obtusata ; fronde pedali et ultra decomposite dicliotoma flabelliformi ; seg- 

 menlis lato-linearibus ancipitibus linearibus obtuse truncatis ; coccidiis sparsis. 



Melanthalia obtusata, J. Ag. Sp. Jig. v. 2. p. 614. Harv. Alg. Austr. 

 Exsic. n. 320. 



Melanthalia Billardieri, Mont. An. Sc. Nat. ser. 2. v. 20./?. 296. Kutz. Sp. 

 Alg. p. 784. Mont. Sylloge, p. 417. 



Rhodomela obtusata, Ag. Sp. Alg. p. 383 ; Syst. p. 200. 



Fucus obtusatus, Labill. Nov. Roll. p. 255. Turn. Hist. t. 145. 



Var. (3. intermedia ; frond very narrow, excessively branched. 



Var. /5. intermedia ; fronde angustissima, ramosissima. 



Melanthalia intermedia, Harv. Alg. Exsic. Austr. n. 319. 



Melanthalia abscissa, Hook, et Harv. Alg. Tasm. in Lond. Joitrn. v. 4. 

 p. 548 (excl. syn.). 



Melanthalia Jaubertiana, Sond. in Linn. v. 25. p. 689 (excl. syn.). 



Hab. On rocks, etc., in the Laminarian zone. South coast of New Hol- 

 land, from Cape Northumberland eastwards, Labil/ardiere, etc. Hi- 

 voli Bay, Br. Mueller. Common on the coast of Vicloria, and through- 

 out Bass's Straits, Br. Mueller, W. II. II., etc. Tasmania, Gann, C. 



