102 BRITISH MARINE ALGA. 
this plant is a full blood-red, the older portions turning black in 
drying. 
Tribe 4, Polysiphoniew, contains the beautiful and extensive genus 
Polysiphonia, as well as the genus Rytiphlea. In fact, three species of 
the latter are now included by Professor Agardh in his genus Polysiphonia, 
the number of species in Rytiphlea being thus reduced, at least in Britain, 
to the well-known species, Rytiphlea pinastroides, which I will first de- 
scribe. This common plant is found pretty frequently on the southern 
shores of England growing in rock-pools, in densely branched bushy tufts 
from 4in. to 10in. high, spreading out on all sides, the branches throwing off 
asecond and third series near the upper portions, and all the divisions 
being set, chiefly on one side of the branches, with short ramuli, which are 
hooked at the tips, or curved inwards; and on these, during winter, small 
roundish capsules are produced, seated usually on the inner sides. Tetra- 
spores, on distinct plants, are imbedded in these incurved ramuli. The 
whole frond of this species is marked with distinct transverse lines, which 
can only be seen when the plant is gathered fresh from the sea, as it always 
turns black in drying. 
Fig. 97 represents a terminal branch of Rytiphlea pinastroides, magnified, 
showing the transverse striz and ceramidia. The fronds of this species 
are extremely difficult to mount on paper, being rigid, and of a cartila- 
ginous substance. My own plan is to display and press those portions 
which I care to retain, in the usual manner, and when the whole is 
tolerably dry, to immerse the specimen in skimmed milk for a quarter 
of an hour, and then dry and press as before; when, in the course of a 
day or two, upon removing the blotters and calico, the plant will be found 
firmly attached to the paper. 
In describing the three transferred species of Rytiphlea, I must confess 
some regret at their removal from the genus, for the external appearance, 
at least, of their stems and branches was certainly characteristic of the old 
name, which signifies “‘.wrinkled bark,’’ the peripheric, or external layer 
of cells, being small and numerous, giving to the surface of the plant when 
dry, a transversely wrinkled appearance; but the inner structure of the 
plants, and their fructification, are clearly those of Polysiphonia, hence 
their removal to that genus. However, before I enter on a description of 
that extensive and beautiful tribe of plants, I will dispose of the three 
species which have hitherto been included in Rytiphlea. Figd 98 
represents a branch of the very rare R. complanata. I have never taken 
this species in any other locality than Cawsand Bay, near Plymouth. 
Possibly its extreme rarity may be due to the fact that fruit on this species 
is of very rare occurrence; indeed, when Dr. Harvey described this plant 
about five and twenty years ago, giving the south of England and the west 
of Ireland as its then known habitats, he remarked “‘ that the fruit of this 
species had not been found in Britain.” The colour of this pretty species 
is a dark brown-red, turning blackish in drying. In freshly gathered 
specimens, and before decomposition has set in, the frond is seen to be 
