at the apices of the lacimae it is marked with radiating stria? ; these striae 

 are internal veinlets, forming part of the axial system of the membrane. 

 The membrane is composed of a double row of quadrate cells ; the midrib 

 of several rows of similar but smaller cells. Fructification, of both kinds, 

 is abundantly scattered over both surfaces of the membrane in fertile speci- 

 mens. The ceramidia are tufted, pedicellate, ovate, and contain a tuft of 

 pedicellate, pyriform spores. The stichidia, also tufted, are fusiform or clavate, 

 simple, and contain a double row of tetraspores. The substance is firmly 

 membranous, the surface glossy when dry, and the frond generally adheres 

 to paper in drying. The colour is a dark vinous-purple, which changes to 

 brown or black in drying, and can only be partially preserved by repeated 

 washing and maceration in fresh-water. 



At the time the figure in ' Nereis Australis' was published, I 

 had seen only very imperfect specimens of this plant, and was 

 only acquainted with the tetrasporic fruit. My recent visit to 

 Australia has furnished me with abundant specimens in all 

 stages of growth and decay; and some of these are so different 

 from the earlier examples, that I was led into error in publishing 

 as a new species, what I now consider to be merely a luxuriant 

 form of the young plant. Different specimens differ consider- 

 ably in the strength and definition of the midrib, and in the 

 breadth and composition of the lamina. The figure now given 

 may be considered characteristic of the usual form of the species. 



As a genus, Jeannerettia is very nearly related to Pollexfenia, 

 and differs from it exactly as Delesseria differs from Nitophyl- 

 lum, namely, by having a midrib and a symmetrical frond. 



Fig. 1. Jeannerettia lobata, — the natural size (a branch only). 2. Small 

 portion of the membrane, viewed vertically. 3. A section of the same. 

 4. Clustered ceramidia. 5. Spores, from the same. 6. Clustered stichidia. 

 7. A stichidium, more enlarged. 8. A tetraspore : — the latter figures more 

 or less magnified. 



