CERAMIACEJ3. 199 



Order XX. CERAMIACEiE. 



Bed or Brown-red Sea-weeds with a thread-like, jointed, more 

 or less harked, one-siphoned frond ; the hark, when present, 

 formed of many-sided cells. Spores congregated in masses 

 (favellce) in transparent memhranous sacs, which are either 

 naked or surrounded by a collar of short hranchlets ; tetra- 

 spores external, formed either from the tips of the frond 

 or the hark-cells. 



Genus XCIV. MICROCLADIA. 



Frond flattened, forkedly branched, composed of a jointed 

 axis, not visible on the surface, surrounded by a thick bark, 

 which is formed of two series of cells ; those within large, 

 angular ; those without small. Spore-clusters (favellae) seated 

 on the branches, surrounded by a collar consisting of a few 

 short branchlets. — Microcladia, from the Greek mikros, 

 small, and klados, a branch. 



Microcladia glandulosa. The glandular Mi- 

 crocladia. 



Fronds growing in tufts, from one to four inches high, 

 somewhat flattened, much branched in an irregular manner ; 

 branches forked, the same width throughout, with very 

 patent axils and short branchlets, which are either awl- 

 shaped or bifid, and hooked at the tip. Spore-clusters 

 somewhat globular, seated on the outer margin of the 

 branches ; tetraspores tripartite, or rarely cruciate, arranged 

 in a line in the substance of the outer edge of the branch- 

 lets. 



The first authentic specimen of this rare and inter- 

 esting plant was found by Mrs. Griffiths on the coast of 

 Devonshire in the year 1803. Other specimens have 

 subsequently been found in the same neighbourhood, 



