8 
in diameter from £ line to an inch. In most instances, these 
foramina are larger, the nearer they are to the nerve; and 
in that situation, their margin is mostly undulated, so as to 
have a crenulated appearance. This circumstance gives the 
frond a very pretty and characteristic aspect; which the 
other species do not possess. The margin of the leaf is per- 
fectly entire, neither serrated nor waved, its whole consist- 
ency very firm, and almost cartilaginous. The second Fucus 
of this family, which may certainly be referred to Turner’s 
figure, I have called F. eribrosus. It differs essentially from 
the former individual, and, in general, scarcely attains a 
third of the size. The frond is even, scarcely waved at all, 
and nearly as membranous as an Ulva: its form is oval-lan- 
ceolate, somewhat cordate at the base. The whole frond, 
properly speaking, is perforated like a sieve; the holes, 
which are more or less round, present but little difference 
in their size, the largest being about 3 or 4 lines in diameter. 
There is nothing of that crenulated appearance in the 
margin which marks the preceding species. The younger 
holes, situated nearest to the base, are peculiar in having 
their margins alternately directed to one or other side of 
the frond; the nerye, which at first is somewhat broader 
towards the middle of the leaf, is very narrow at its base, 
even slenderer than the stem, which has the uniform thick- 
ness of twine, and is about 2} inches long. I saw this 
species frequently clothed with a web-like, new, and unde- 
scribed Sertularia. It occurs in the Bay of Awatscha only. 
“Lastly, the third species, which I have called F. per- 
tusus, differs from the two others in its perforations not 
appearing at first: for instance, at the base of the fronds, 
instead of holes, we there observe only small cavities, 
and bladder-like protuberances, in which the substance of 
the leaf is afterwards seen to be wanting, and which finally 
form the circular, though more or less distorted, foramens. - 
Similar protuberances and hollows cover the whole frond 
between the holes. In the form of the frond it probably 
bears some affinity to the first species, but the imperfect - 
specimens which I have hitherto found do not enable me to 
