18 BRITISH MARINE ALG. 
beautifully arched outline, but it serves to convey a very good general 
idea of the appearance of growing plants of this genus. 
Let me now direct the reader’s attention to the group of drawings, 
Fig. 21. Letter a is the terminal sprig of Cladophora pellucida. I describe 
this plant as among the Cladophora, though, I regret to say, it has been 
removed from that genus, and it is now, I believe, the only British 
representative of the genus Leptocystea. It is most easily recognised, not 
only by its perfect regularity of branching, but by there being only one 
long cell or joint between each furcation or forking of the branches. 
Almost all the branches are set at rather acute angles exactly opposite to 
each other on the sides of the stems, and the terminal ramuli are single 
jointed, much shorter than the other articulations of the plant, and three 
in number. All the branches of this species are stiff and wiry, and the 
dark green endochrome in the joints is surrounded by a pellucid or 
colourless border. Letter 6b, is a lateral branchlet of C. rupestris. In 
all states of this plant the colour is a very dull dark green, and the 
branches and ramuli are stiff and harsh to the touch; the ramification 
is very regular, and, once having had its characters pointed out, the 
student will have no difficulty in recognising the species. Letter c 
embraces two filaments, one is a terminal branchlet of the pretty species 
C. arcta, in which the joints are about thrice as long as broad, the other 
represents a portion of the lower parts of the plant in which the articula- 
tions are pretty nearly of equal dimensions. This is a favourite species 
with collectors, as it adheres very well to paper, and preserves its fine 
glossy green in drying. Letter d is a terminal branchlet of C. letevirens. 
In this species the articulations are of very great length in proportion to 
their breadth. In early growth the plant is a fine bright green, which 
becomes gradually paler as it advances towards maturity. This is one of 
tne commoner forms of marine Cladophora, and is identical with the fresh- 
water species, Cladophora glomerata. Letter e is a terminal sprig of C. 
refracta, one of the most bushy and densely branched of the genus. The 
young student may study this drawing for some time ere he will carry in 
his memory the variety displayed in this one terminal sprig of C. refracta. 
If, however, he chance to find this species, he may easily identify it by a 
comparison with my figure, which, like all the others, has been drawn 
from the living plant as accurately as possible. There are several other 
species of this beautiful tribe of seaweeds, some of which are minute and 
others rare; among the latter is the fine species Cladophora Rudolphiana, 
a specimen of which I possess, but I have never found this species on the 
English shores. It occurs only, I believe, in Roundstone Bay, and in one 
or two other stations on the coast of Ireland. OC. gracilis is one of the 
most delicate and beautiful of the genus. OC. fracta is an exceedingly 
bushy plant. C. albida is a fine species, but turns to a pale whitish green 
in drying, whence its specific name. CO. flexuosa is a pretty species with 
wide-spreading branches. CO. Balliana is a tolerably well-marked species. 
C. uncialis, as its name implies, is about an inch in height and grows on 
