ceramiacejE. 219 



stricted at the joints. Pavellae not known ; tetraspores on 

 the inner facej of short, involucral branchlets, which are 

 densely whorled round the joints of the main stem. 



This species is very rare, and confined to southern 

 localities, where it grows on mud in deep water, and 

 must therefore be obtained by dredging, or when float- 

 ing or cast up by the waves. It resembles G. bar- 

 bata, but is separated from that species by the position 

 of the tetraspores, and by the less uniform length of the 

 branches. 



Griffithsia barbata. The bearded Griffithsia. 



Pronds tufted, very slender, repeatedly and regularly 

 forked ; articulations from five to eight times as long as 

 broad, slender at the base, becoming thicker and rounded 

 at the apex, those of the terminal branches giving off slen- 

 der, byssoid, forked, spreading branchlets. FavellaB in pairs, 

 stalked, formed out of truncate branches, and surrounded 

 by numerous, simple or forked, involucral branchlets ; tetra- 

 spores spherical, attached singly to the branchlets, which 

 spring from the upper branches. 



Though far from common, this species is less rare than 

 the last. It grows parasitically, is annual, and fruits 

 in summer. I have found it in great abundance in 

 Jersey, floating at the edge of the tide. I have also 

 seen specimens from Brighton and other localities. 

 When laid out on paper, the frond is fan-shaped, and 

 the tuft forms nearly a perfect circle. 



Genus CI. SEIROSPORA. 



Fronds rosy, thread-like ; stem and branches jointed, one- 

 tubed, veined. Fructification, tetraspores disposed in neck- 



