carp, and bears from all parts of its surface, pedicellate, obovate spores, 

 rather densely set, and deeply coloured. The tetraspores are lodged among 

 the cortical cellules of swollen, pod-like tips of the branches, these tips 

 hooking backwards : they are less common than the conceptacles. The 

 colour is a dark brownish-red, preserved in drying. The substance is rigid, 

 somewhat horny when dry, and the plant does not adhere to paper. 



A curious little plant, first found by Gaudichaud ; but by me 

 only met with in the locality above noted, close to Mr, Cheyne's 

 hospitable house at Cape Riche. There it occurred in February, 

 1854, in great profusion, thickly covering the stems of Ci/iiio- 

 docea antarctica, at low-water mark ; and among the hundreds 

 of specimens which I collected, there was no valid variation in 

 size or form, and no tendency to pass into D. GreviUil. I am 

 therefore disposed to consider the present a distinct species. 



Agardli places the genus Dicranema in the Fam. 8phcerococ- 

 coidecs, near Dicurella, — and as far as habit goes, there is much 

 resemblance between these genera. But to me the parietal 

 Jibro-ceUidar placenta, derived from the medullary layer, together 

 with the form of the spores, and the shortness of the spore- 

 threads, and the position of the zonate tetraspores in terminal 

 pods, point rather to an affinity with Gelidiacea, where there- 

 fore I place the genus. The structure of its conceptacles is ana- 

 logous to that of Pterocladia ; that of the frond is not very dif- 

 ferent from that of Hypnea. 



At present Dicranema includes three species, D. revolutmn^ 

 D. Gremlin, and B.filiforme. The "i>. pusillum" of my Austr. 

 Algse, n. 313, on more careful re-examination, proves to be a 

 species of Mycliodea. 



Fig. 1. A tuft of DiCKANEMA REVOLUTUM, growing on the stems of Cymadocea 

 antarctica, — tlie natural size. 3. Portion of a frond, with conceptacles 

 below the tips. 3. Cross section of a conceptacle. 4. Spores from the 

 same. 5. Portion of a frond with pod-like tips containing tetraspores. 

 6. Section of the cortical layer of a swollen tip, showing the tetraspores in 

 situ. 7. Tetraspores. 8. Cross section of the frond : — all but the first 

 figure more or less magnified. 



