fi8 BRITISH SEA-WEEDS. 



Mesogloia GrifSthslana. Mrs. GrifEths's Meso- 

 gloia* 



Fronds from a foot to a foot and a half high, with a slen- 

 der stem of equal thickness throughout, bearing long, alter- 

 nate, thread-like branches, either naked, or with a few short 

 branchlets set on, at nearly a right angle to the branch, at 

 distant intervals. 



This species is of a pale olive-green colour, and its 

 spores have short stems. It was discovered by Mrs. 

 Griffiths, whose name it appropriately bears. The re- 

 corded habitats are chiefly on the south-west coast, and 

 in Ireland, and even in these localities it is not of fre- 

 quent occurrence. 



Mesogloia virescens. Pale-green Mesogloia. 



Frond from a few inches to a foot long, with a slender, 

 cylindrical, undivided stem of the same thickness through- 

 out, and bearing numerous side-branches, which are thickly 

 studded with short simple branchlets. 



The colour of this plant is a pale yellowish, or green- 

 ish-olive. Its spores are without stems,- and the fila- 

 ments of the periphery consist of a short stem, bearing 

 a bundle of forked, beaded branches. 



Genus XXVIII. LEATHESIA. 



Frond tuberous, composed of jointed, forked threads. 

 Fructification, oval or pear-shaped spores hidden among 

 the outer series of filaments. — Leathesia, named in ho- 

 nour of the Eev. G. E. Leathes, a British naturalist, who 

 discovered the first specimens which were described. 



This genus is widely distributed in various latitudes. 



