confervace^:. 259 



veloped. — Leptocystea, from the Greek leptos, slender, 

 and kustis, a bladder. 



The only British species belonging to this genus has 

 been hitherto included among Cladophorce , and I have 

 hesitated whether to depart from that arrangement. 

 There can, I think, be little doubt that the genus Cla- 

 dophora, containing, as it has been made to do, all 

 the branched species of the order Confervacece, must be 

 ultimately divided ; and it appears to me that this plant 

 possesses sufficiently distinct characters to entitle it to 

 be placed in a separate genus. This course has been 

 adopted by Dr. Gray in his ' Handbook of British 

 Water-weeds/ and I follow it here. 



Leptocystea pellucida. The transparent Lepto- 

 cystea. 



"Fronds from three to eight inches high, growing in tufts 

 or singly, very rigid ; stem undivided below, forked above, 

 and ultimately repeatedly branched in a dichotomous or 

 trichotomous manner; branches opposite, or more or less 

 whorled, springing regularly from each articulation. 



This is a very handsome, and by no means uncom- 

 mon plant. It grows in pools near low-water mark, 

 and is probably annual. The arrangement of the 

 branches at the top of each of the long one-celled 

 joints of the frond is a very obvious character, and 

 affords a never-failing means of recognition. 



Genus CXII. CLADOPHORA. 



Frond tufted, uniform, jointed, branched; cells oblong, 

 usually more than one between each two branches or sets 

 of branches, filled with granular endochrome, from which 



s 2 



