braiiclilcts, 1 ,j-4 inclies long, and ^-h line, or rather more, in diameter. 

 These rmiinU taper to hase and apex, and are sometimes sim])le, but more 

 generally, like the frond itself, they are twice or thrice forked. The frond is 

 composed wholly Qi filaments ; those of the axis are longitudinal, densely 

 packed, somewiiat branched, interwoven, and lying in moderately tirm gela- 

 tine ; those of the peripliery are many times forked, surrounded by much 

 looser gelatine, and their coloured apices are moniliform. ^^Vtfavdlce are im- 

 mersed in the ramuli, at the base of the peripheric filaments, and surrounded 

 by a gelatinous periderm. The tetrasporcs, on separate plants, are hidden 

 among the moniliform extremities of the peripheric filaments of the ramuli : 

 they are c?-uciafe. The colour when quite recent is a rather dull brownish- 

 purple, which is soon expelled in fresh-water, and the plant fades to pale 

 rufescent-brown. The substance is gelatinous and elastic, soon softening 

 and becoming slimy in fresh-water, and in drying the frond adheres very 

 closely to paper. 



If this plant be correctly referred to Nemastoma, of which it 

 has tlie fruit and general structure, it is by much the largest and 

 finest species of the genus. Though the dicliptomous branching 

 is in some degree concealed by the distant furcations and abun- 

 dance of lateral ramuli, it is nevertheless present, and exists even 

 in the ramuli, so that our plant agrees tolerably with other 

 species in the proper evolution of the frond. There is some 

 similarity externally to Helmintliocladia, but the structure of the 

 cystocarpic fruit is very different. 



When preparing the figure I had not observed tefraspores. 

 They are abundantly dispersed among the moniliform filaments, 

 forming the outer wall of the slender lateral ramuli, and occur 

 in more luxuriant and comose specimens than those that bear 

 cystocarps. 



Fig. 1. Nemastoma? comosa, base of a (six feet long!) frond, — the natural 

 size. 2. Segment of a transverse cutting of a ramulus, showing two favellfe 

 lying beneath the excurrent peripheric threads. 3. Some spores: — mag- 

 nified. 



