broadest in the middle, slightly tapering toward each extremity. Older 
fronds very frequently become irregularly proliferous from the main stem 
and from the rachides of the larger pinne; in these cases many tripinnate 
distichous branches are directed to all sides, causing the general frond to 
lose its distichous aspect and become densely bushy, the fronds and their 
proliferous frondlets closely imbricating each other. The midrié varies 
much in different specimens; in some it is scarcely obvious, in others 
strongly marked, very convex, and much thickened. Sometimes the pin- 
nules are short or abortive and crisped; sometimes they are much at- 
tenuated, flat, and thin. The conceptacles are formed about the middle of 
the pinnule, in dilated portions, and resemble in structure the semi-con- 
ceptacle of a Gelidium, as if one side only of the conceptacle were developed. 
The ¢etraspores are cruciate, formed among the cortical filaments of dilated 
pinnule, near the summit. The colour is a rather brilliant purplish-red. 
The surface of the frond is glossy, and retains its gloss in the herbarium. 
The substance is rigid and very tough, coriaceous when growing, somewhat 
horny when dry, in which state the frond does not adhere to paper. 
From Geldium, to which genus it is nearly allied, Pferocladia 
differs in having a one-celled, not a two-celled pericarp, and 
scarcely by any other character ; for Gelidium proliferum (Plate 
CCIV.), as already noticed, unites the fruit proper to Gelidium 
to the habit and frond of Péerocladia. 
Pterocladia lucida, if all the specimens that pass under this 
name be justly referable to one species, is nearly as variable a 
plant as Gelidium corneum. Our figure is intended to represent 
the typical state of the frond, before it has become complicated 
by proliferous additions. The New Zealand plant may possibly 
be specifically different, thongh hitherto I have not succeeded in 
detecting a valid difference between it and that from West Aus- 
tralia. If all belong to one species, then it is a curious fact that 
this species should be so common in West Australia and in 
New Zealand, and not found on the intermediate coasts between 
these widely-separated centres. 
Fig. 1. Prerocnapia Lucipa,—the natural size. 2. Apex of a pinna, bear- 
ing conceptacles. 3. Vertical section of a conceptacle and of the frond. 
4. Apex of a pinna, bearing tetraspores in dilated pinnule. 5. Tetra- 
spores :—all magnified. 
