Ser. Melanosperme/e. Fam. Fucacea. 



Plate XXIV. 



MYRIODESMA LATIFOLIA, Harv. 



Gen. Char. Root discoid. Stem terete, branched ; the branches termi- 

 nating in dichotoinous, raidribbed leaves. Proper receptacles and 

 vesicles none. Spore-cavities scattered over both surfaces of the 

 leaves, hemispherically-prominent, monoecious. Spores obovoid, sub- 

 sessile. Paranemata simple. — Myriodesma {Bene.), from fivpios, a 

 thousand, and Beo-fir), a tuft or cluster; from the numerous spore- 

 clusters. 



Radix scutata. Canlis teres, ramosus ; ramis in phyllodia dichotoma costata 

 desinentibus. Receptacida propria et vesicidce nulla. Scaphidia in ulraque 

 pcujina foliorum sparsa, hemispha 'rice prominentia, monoica. Spores obovoidece, 

 subsessiles. Paranemata simpliciuscula. 



Myriodesma latifolia ; leaves broadly linear, pinnato-dichotomous, multi- 

 partite, sharply serrate; spore-cavities very numerous and densely 

 set. 



M. latifolia ; phjllodiis lato-l'mearibus pinnato-dichotomis multipartitis ser- 

 ratis ; scaphidiis numerosissimis, densissime sparsis. 



Myriodesma latifolia, Harv. in Trans. R. I. Acad. v. 22. p. 354 ; Austr. 

 Exsic. n. 42. 



Hab. "Western Australia. At Garden Island, W. H. H. 



Geogr. Distr. As above. 



Descr. Root ? Fronds 2-3 feet long. Stem shrubby, 1-2 lines in diameter, 

 terete or subcompressed, much branched, flexuous, irregularly dichotomous, 

 or, by occasional suppression, subpinnate. Branches patent, short, passing 

 into the bases of the leaves, aud continued upwards as a forking midrib, 

 until lost in the alternate segments. Leaves 8-1 2 inches long or more, from 

 half an inch to an inch or more in breadth, repeatedly dichotomous, but 

 irregularly ; one arm of the fork being frequently suppressed, the ramifica- 

 tion is partly pinnato-flabelliforra and partly dichotomous. Sometimes the 

 middle segment is mnch prolonged into a jugament, and regularly pinnated 

 with dichotomous segments. The margin is sharply serrate throughout. 

 The midrib is strongly marked and thickened in the lower segments, but 

 becomes fainter and fainter towards the summit, where it nearly vanishes 

 altogether. The spore-cavities are very densely sprinkled over the whole 

 surface of the leaves, without any regular order ; they resemble minute 

 pustules, and are of a darker colour than the leaf. Spores and tufted an- 

 theridia are found in the same cavity. The substance, though thin, is co- 

 riaceous. The colour is a dark fucoid brown. 



