Pinnules 3-6 lines long, cylindrical, obtuse, not a line in diameter, either 
simple or more frequently forked, the arms long or short, sometimes twice 
or thrice forked, scattered or crowded, always widely spreading, and often 
horizontal. Cystocarps (which I have not seen) solitary, immersed in the 
ends of the forks of the pinnules. Zeéraspores forming long sori, immersed 
in the substance of the ramuli, very numerous and densely packed, dark 
purple, cruciately parted. Colour a dark, lurid and dull purple, changing 
on exposure to pale horn-colour or greenish-yellow. Sudstance cartilaginous 
and firm, horny and rigid when dry, in which state the frond does not in 
the least adhere to paper. 
PPI IIe 
The young and the full-grown specimens of this plant are re- 
markably diferent, as may be seen in fig. 1 of our Plate; the 
young plant being either quite simple, or once or twice forked, and 
destitute of lateral ramuh ; the fuli-grown, on the contrary, copi- 
ously pinnate or bipinnate. Though there is a peculiarity of 
habit among all the specimens I have seen, yet some of them 
approach suspiciously near to some forms of G. pinnalu, J. Ag. 
(itself a variable plant), and it is possible that a fuller suite of 
specimens might connect the two; or even that both should be 
regarded as varieties of the older G. /ivida. Small differences in 
ramification are scarcely sufficient to separate plants otherwise so 
strongly related. Our figure, however, represents what may be 
called the typical form of G. disticha, Sond. 
Fig. 1. GIGARTINA DISTICHA,—+the natural size. 2. Cross section, to show the 
structure of the frond, and an immersed sorws of tetraspores. 3. Tetra- 
spores :—both magnified. 
