( 48 ) 



Structure densely cellular or fibro-cellular, the axial cells larger, disposed 

 in longitudinal series ; from these arise others more slender, inclined, 

 terminating in others very slender, vertical and moniliform. Substance 

 cartilaginous, horny when dry. Coloui-, a deep dull piu-ple, passing 

 through greenish, dull orange, to white in bleaching. I'avellidia un- 

 known to us, and, so far as we know, have not been observed in this 

 country, Nemathecia (?) are very common, but their metamorphosis 

 into tetraspores is very imperfectly known, indeed we have never seen 

 perfect fruit of any kind, on British specimens of this species. 



This singularly wiry-looking plant is extremely abundant in this 

 country, and appears to be equally abundant in many others, and we are 

 informed in Phyc. Brit, that it is almost cosmopolitan in its habitat. 



Although so common a plant, it seems to produce perfect fructification 

 but seldom, at least in this country, and is consequently very imj^er- 

 fectly imderstood. Specimens without nemathecia, if they be really 

 such, are very seldom met with, and they are generally abundant, but 

 our knowledge of their ultimate form is still a desideratum. 



Its favourite habitat is the bottoms of intratidal rock-pools, where it 

 generally grows singly, more rarely tufted, generally very much branched, 

 and often excessively and intricately entangled. The branches are gene- 

 rally single, but occasionally a number of them arise from the same 

 point, forming a dense bundle, very much resembling those nest-looking 

 branches so commonly observed on birch trees, which give a singular 

 and fantastic character alike to both ti'ee and Alga. 



The species possesses no great beauty or attraction in its natural 

 element either for its colour or form, but when partially bleached into a 

 rich yellowish brown colour, it is by no means destitute of beauty, and 

 in its native rock-pool its harsh wiry stems give variety to the vegeta- 

 tion, which constitutes at all times an important element in the beautiful 

 and agreeable. 



EXPLANATION OF PLATE LXXXIV. 



Fig. 1. — Ahnfeldtia 2^licata, natural size. 

 2. — Branclilet witli nemathecia (?). 

 3. — Section of a nemathecium. 

 4. — Segment of same. All magnified. 



