breadth ; it always tapers mucli to tbe base, but does not greatly narrow 

 upwards. The primary hranches are similar to the main frond, tapering 

 much to the base, sub-horizontally patent, simple or unilaterally or alter- 

 nately lobed or branched, and 4-8 inches long. The whole margin of all 

 the branches is closely pectinated, at distances of a line or less, with slender, 

 narrow-linear, horizontal, simple or branching ramuli, -f— If inches long, 

 and rarely a line wide. Different specimens vary extremely in the minor 

 characters of the branching, some being much more divided and ramuli- 

 ferous than others. Cystocarps either marginal or scattered on the disc, 

 produced either in the ramuli, or on the branches, having a wide cavity and 

 few-spored nucleus ; tlie spores elliptical, imperfectly seriated. Tetraspores 

 lodged in the intermediate stratum, dispersed. Colour, when quite fresh, 

 a blood-red, fadhig on exposure or immersion in fresh-water. Substance 

 soft, decomposing, after a time, in fresh-water. In drying the frond adheres 

 closely to paper. 



This fine species, one of the most showy of the Victorian 

 Algae, though long known to botanists by the figure in Turner's 

 Hist. Euc, Avas, until recently, in very few European herbaria; 

 and though I had myself gathered some hundreds of speciiuens, 

 on none did I find ci/stocarpic fruit in a mature condition. For 

 fine specimens, in full fructification of both kinds, I have^now 

 to thank Mr. Rawlinson of Melbourne, to whom (through Dr. 

 Mueller) I am also indebted for a suite of well-dried Alg8e,^col- 

 lected at Port Phillip Heads. 



The structure of the nucleus in this species and in H. divari- 

 caia (Plate XX.), necessitates the placing of the genus Hymeno- 

 cladia among the Wiodymeniacece instead of the LaurenciacecB, 

 Avhere Agardh refers it. 



Our Plate has been struck in rather too dark an ink, and is 

 more highly coloured than ordinary specimens ; but when quite 

 fresh, before exposure to the sun or immersion in fresh-water, it 

 is of the deep red here represented. 



Pig. 1. Hymen OCLADIA Usnea, — the natural size. 2. Section of a concep- 

 tacle. 3. Spores from the same. 4. Cross section of the frond, with im- 

 bedded tetraspores. 5. A tetraspore : — the latter figures variously mag- 

 nified. 



