(10) 



pinnate or subdichotomous. Air-vessels small, contained in the branchlets, 

 and often subtending the axils, " The branches of yoinig plants, and 

 occasionally of the younger parts of the stem in old plants, are flat and 

 leaf-like, bipinnate ; the pinnules furnished with a midiib and muci- 

 ferous pores, with a crenate or subdentate margin, and varying from a 

 line to two or three lines in breadth." — Phyc. Brit. Eeceptacles oblong 

 or lanceolate, frequently forked, without spine-like processes. Substance 

 coriaceous, hard and brittle or subcartilagiuous, not adhering to paper. 

 Colour greenish olive in the younger parts, almost black when old or 

 when dried. 



We are very imperfectly acquainted with this species, and gladly 

 follow Dr. Harvey in combining the two species of most authors, 

 although we have not the variety referred to F. discors, and are unable 

 to give any opinion of its character, whether as a species or variety. 



It is one of our rarer species, being confined to the southern and 

 south-western shores of England and the Channel Islands, and seems 

 nowhere very abundant. 



It may be readily distinguished from the other species of the genus 

 by the smooth receptacles and the somewhat "compressed stem," as 

 well as by the cm-ious spine-like tu.bercles with which the stem and 

 main branches are covered ; these from their number would seem rather 

 to be analogous to hairs, or at least to the seta3 of some kinds of land 

 plants, than to spines. 



EXPLANATION OF PLATE CXXXIIL 



Fig. 1. — Cystoseira fceniculacea, natural size. 

 2. — Brancli with receptacles. 

 3. — Section of receptacle. 

 4. — Section of conceptacle. 

 6. — Spores and filaments. All magnified. 



