(36) 



divided, with broad, rounded axils, and their apices broad and obtuse 

 or emarginate from the formation of another dichotomy. Sometimes 

 the stem and branches, especially upwards, are more or less fringed with 

 small foliaceous processes, oblong or spathulate, simple or bifid, occa- 

 sionally long, linear and strap-shaped. Structure uniformly cellular; 

 central cells small, those at the surface veiy minute, all more or less 

 coloured, more deeply towards the sm-face. Substance firm, rigid, and 

 somewhat cartilaginous, not adhering to paper. Colour, a dark brownish 

 purple, changing to greenish yellow and yellowish white in decay. 

 Tubercles arising from the sides of the upper part of the stem as well 

 as the branches and bases of the frondlets, obovate, on short stalks, 

 composed of densely packed moniliform filaments, and containing a mass 

 of minute roundish spores. Nemathecia, dark pm'ple wart-like bodies, 

 of a somewhat irregularly triangular foi-m, occupying the centre of the 

 leaflet, eqiially on both sides, but not permeating the leaflet, and formed 

 of vertical moniliform filaments ; on the same or on distinct plants 

 from those bearing tubercles. Tetraspores we have not seen. 



This handsome species is of equally common occmrence as the pre- 

 ceding, occupying similar localities. The nemathecia, as they are presumed 

 to be from then- peculiar organisation, are not unfrequent. The tuber- 

 cles appear to be less common, and the tetraspores seem to be unknown. 



It is readily distinguished from the preceding by its much darker, 

 broader, more flabelliform leaflets, and elongated stems, stalked tubercles 

 and curious nemathecia ; from Rltodymenia Palmetta it may in general 

 be known by its more regularly cylindrical stem, and the broader and 

 more obtuse or trimcate apices of the segments of the frond. 



The true natm-e of the nemathecia is as yet but very imperfectly 

 understood. They are composed, as above stated, of radiating moniliform 

 filaments, very much resembling the structure of the crustaceous Algte, 

 and rest on the surface of the frond, with only the surface cells of which 

 they can have any organic connexion, the central cells remaining un- 

 changed between them ; yet it is deserving of notice, that the nemathe- 

 cium extends almost always uniformly and equally on both sides of the 

 frond on which it is produced. No change of the articulations of its 

 filaments either into spores or tetraspores, however, seems yet to have 

 been observed, and its true nature still remains an interesting lield for 

 the investigation of the phycologist. 



EXPLANATION OP PLATE LXXIX. 



Fig. 1. Phylloj}liora memhranifolia, natural size. — 2. Fragment of frond with tuber- 

 cles. — 3. Section of tubercle. — 4. Filaments from its walls. — 5. Frond with 

 nemathecium . — 6. Section of part of same. All magnified. 



