196 BRITISH SEA-WEEDS. 



periphery ; tetraspores not known. — G-IiOiosiphonia, from 

 the Greek gloios, viscid, and siphon, a tube. 



The single species of this genus is widely distributed 

 on the shores of the Atlantic Ocean, in both hemispheres. 

 Its characters are very distinct, and the frond has a very 

 curious structure, not easy to describe. Dr. Harvey 

 speaks of it as wholly composed " of articulated confer- 

 void filaments, invested with transparent gelatine ;" and 

 with reference to the change which takes place in the 

 axis, he remarks that it arises " either from distension 

 or the perishing of the central cells." 



Gloiosiphonia capillaris. The slender Gloio- 

 siphonia. 



Frond from a few inches to a foot long, filiform, much 

 branched, very tender and gelatinous, composed of jointed 

 filaments enveloped in transparent gelatine, when young 

 comparatively solid, becoming tubular with age. Spores 

 numerous, in clusters sunk in the branches beneath the outer 

 series of filaments. 



This is a very delicate and beautiful plant. It grows 

 in deep water or in tide-pools. It is annual, and in per- 

 fection in summer. The recorded habitats are numerous 

 all round our coast, but my own experience leads me to 

 consider it a rare plant. It should be laid out in sea- water, 

 or it will lose its colour. 



Genus XCII. DUMONTIA. 



Frond tubular, when young filled with a loose network of 

 anastomosing filaments, which become obsolete as the plant 

 matures and leave the tube empty ; the wall of the tube 

 is formed of an inner series of elongate, jointed cells, 



