Ser. Khodosperme^. Fam. Modymeniacea. 



Plate CXVIII. 



HYMENOCLADIA USNEA, /. A^. 



Gen. Char. Frond softly membranaceous, flat, linear, distichous, decom- 

 poundly pinnated, composed of three strata of cells; the medullary 

 stratum of large, roundish, inflated cells j the intermediate of smaller, 

 angular cells; the cortical of minute, coloured cellules, arranged in 

 vertical, moniliform series. Fructification: 1, conceptacles globose, 

 sessile, with a thick, cellular pericarp, at length opening by an apical 

 pore; spore-threads moniliform, attached to a basal placenta; the 

 spores elliptic or oblong ; 2, dispersed, tripartite tetraspores. — Hyme- 

 NOCLADIA (/. Ag^, from vijl7]v, a membrane, and KKaho<i, a branch. 



Frons gelat'moso-membranacea, plano-compressa, linearis, disticJie decomposito- 

 pinnata, strath tribus contexta ; ynedullari ex cellulis inagnis vcsicatis, inter- 

 media ex cellulis minoribiis rotiindato-angtdatis pluriseriatis, corticali ex cel- 

 lulis minutissimis coloratis infila brevissima woniliformia verticalia conjimctis. 

 Cystocarpia intramarginalia, sitbsphcsrica, sessilia, perica^pio crasso celhdari 

 demum ostiolo aperto, sporas oblongas infila e placenta basali radiantia evo- 

 lutas foventia. Tetrasporce triangule divisa, spar see. 



Hymenocladia JJsnea; frond blood-red, gelatino-membranaceous, di- 

 chotomo-pinnate ; rachis forked, broadly linear, narrowed at base; 

 branches patent, ligulate, closely pectinated with horizontal, long and 

 narrow, simple or pinnulate ramuli; cystocarps and tetraspores 

 scattered. 



H. Usnea ; fronde sanguinea gelatinoso-rnembranacea dicJiotomo-pinnata supra- 

 decomposita ; racldde scepius furcata lato-Uneari basi angustata; ramis patenti- 

 bus V. divaricatis pectinato-pinnatis ; pinnulis liorizontalibus angustis elougatis 

 simplicibus v. iterum pectinato-pinnulatis ; cystocarpiis tetrasporisque sparsis. 



Hymenocladia Usnea, /. Ag. Sp. Alg. v. 2. p. 772. Harv. Alg. Austr. 

 Exsic. n. 365. 



Fucus Usnea, R. Br. in Turn. Hist. Fuc. t. 225. 



Hab. Kent Island, R. Brown. Abundant at Port Phillip Heads, and 

 Western Port, JF. E. R., Dr. Mueller, Mr. Rawlinson, etc. Flinders 

 Island, Br. Mllligan. 



Geogr. Distr. South coast of Australia, east of Cape Northumberland. 



Descr. Root a small disc. Frond tufted, 12-16 inches long, and as much in 

 the expansion of the branches, perfectly distichous, and much and irre- 

 gularly branched in an imperfectly dichotomous order, all the divisions 

 remarkably patent, with wide, blunt axils. The main frond varies from 

 being several times forked to nearly simple, and from 1 to 4-6 lines in 



