348 
hidden during life by the investing membrane. The upper 
latera are triangular, the upper angle curving rather grace- 
fully forwards ; the umbo of growth is apical. 
The rostral latera are long transverse plates lying be- 
neath the basal margins of the scuta. The carinal latera 
are large and triangular, with the apex curved for- 
wards very much like the upper latera, and the infra- 
median latera are very small, but in form and direction of 
growth nearly the same. 
The peduncle is round in section and strong, and 
covered with a felting of light-brown hair. The scales of 
the peduncle are imbricated and remarkably large, some- 
what asin S. ovvatum Darwin. About three, or at most 
four scales, pass entirely round the peduncle. The base 
of attachment is very small, the lower part of the pe- 
duncle contracting rapidly. Some of the specimens taken 
were attached to the lumps of clay and manganese con- 
cretions, but rather feebly, and several of them were free, 
and showed no appearance of having been attached. 
There is no doubt, however, that they had all been more 
or less securely fixed, and had been pulled from their 
places of attachment by the trawl. On one lump of clay 
there were one mature specimen and two or three young 
ones, some of these only lately attached. The detailed 
anatomy of this species will be given hereafter, but the 
structure of the soft parts is much the same as in Sca/ed- 
lum vulgare. 
In two specimens dissected there was no trace of a testis 
or of an intromittent organ, while the ovaries were well 
developed ; I conclude, therefore, that the large attached 
examples are females, corresponding, in this respect, with 
the species otherwise also most nearly allied, S. oxzatum. 
In almost all the specimens which were procured by 
us, several males, in number varying from five to nine, 
were attached within the occludent margins of the scuta, 
not imbedded in the chitinous border of the valve, or even 
in any way in contact with the shell, but in a fold of the 
body-sac quite free from the valve. They were ranged in 
rows, sometimes stretching—as in one case where there 
were seven males on one side—along the whole of the 
middle two-thirds of the edge of the tergum. 
The male of Scalpellum regium (Fig. 2) is the simplest 
in structure of these parasitic males which has yet been 
observed. It is oval and sac-like, about 2mm. in length 
by ‘9mm, in extreme width. There is an opening 
at the upper extremity which usually appears narrow, 
like a slit, and this is surrounded by a dark, well-defined, 
slightly raised ring. The antennz are placed near the 
posterior extremity of the sac, and resemble closely in 
form those of S. vulgare. The whole of this sac, with 
the exception of a small bald patch near the point of 
attachment, is covered with fine chitinous hairs arranged 
in transverse rings. There is not the slightest rudiment 
of a valve,and I could detect no trace of a jointed 
thorax, although several specimens were rendered very 
transparent by boiling in caustic potash, There seems 
to be no esophagus nor stomach, and the whole of the 
posterior two-thirds of the body in the mature specimens 
was filled with a lobulated mass of sperm-cells. Under 
the border of the mantle of one female there were the 
dead and withered remains of five males, and in most 
cases one or two of the males were not fully developed ; 
several appeared to be mature, and one or two were 
dead, empty, dark-coloured chitine sacs. 
On Wednesday, June 18, we resumed our course with 
a fine breeze, force 5 to 7, from the south-east. In this 
part of our voyage we were greatly struck with the absence 
of the higher forms of animal life. Not a sea-bird was 
to be seen, with the exception of a little flock of Mother 
Carey’s chickens, here apparently always 7halassidroma 
wzlsont, which kept playing round the ship, on the watch 
for food, every now and then concentrating upon some 
peculiarly rich store of offal as it passed astern, and stay- 
ing by it while the ship went on for a quarter of a mile, 
SURAT a EL ew, ENRON LS, ene ea 
' NATURE 
i 
[Aug. 28, 1873 
fluttering above the water and daintily touching it with 
their feet as they stooped and picked up the floating 
crumbs, and then rising and scattering in the air to over- © 
take us and resume their watch. 
The sea itself in the bright weather, usually under a 
light breeze, was singularly beautiful—of a splendid in- 
digo-blue of varying shades as it passed from sunlight 
into shadow, flecked with curling white crests ; but it was 
very solitary: day after day went by without a single 
creature (shark, porpoise, dolphin, or turtle) being visible. 
Some gulf-weed passed frem time to time, and bunches 
of aspecies of Fuczs, either F. nodosus or a very nearly 
allied form, evidently living and growing, and partici- 
pating in the wandering and pelagic habits of Sargassum. 
The floating islands of the gulf-weed, with which we have 
become familiar as we have now nearly made the circuit 
of the “ Sargasso Sea,” are usually from a couple of feet to 
two or three yards in diameter, sometimes much larger ; 
we have seen, on one or two occasions, fields several 
acres in extent, and such expanses are probably more 
frequent nearer the centre of its area of distribution. 
They consist of a single layer of feathery bunches of 
the weed Sargassum bacciferum, not matted together, but 
floating nearly free of one another, only sufficiently en- 
tangled for the mass to keep together. Each tuft has a 
central brown thread-like branching stem studded with 
round air-vesicles on short stalks, most of those near the 
centre dead, and coated with a beautiful netted white 
polyzoon. After a time vesicles so encrusted break off, 
and where there is much gulf-weed the sea is studded 
with these little separate white balls. A short way from 
the centre, towards the ends of the branches, the serrated 
willow-like leaves of the plant begin, at first brown and 
rigid, but becoming, farther on in the branch, paler, more 
delicate, and more active in their vitality. The young 
fresh leaves and air-vesicles are usually ornamented with 
the stalked vases of a Campanularia, The general colour 
of the mass of weed is thus olive in all its shades, but 
the golden olive of the young and growing branches 
greatly predominates. This colour is, however, greatly 
broken up by the delicate branching of the weed, blotched 
with the vivid white of the encrusting polyzoon, and 
riddled by reflections from the bright blue water gleaming 
through the spaces in the network. The general effect of 
a number of such fields and patches of weed, in abrupt 
and yet most harmonious contrast with the leaves of in- 
tense indigo which separate them, is very pleasing. 
These floating islands have inhabitants peculiar to 
them, and I know of no more perfect example of protec- 
tive resemblance than is shown in the gulf-weed fauna. 
Animals drifting about on the surface of the sea with such 
scanty cover as the single broken layer of the seaweed, 
must be exposed to exceptional danger from the sharp 
sea-birds hovering above them, and from the hungry 
fishes searching for prey beneath, but one and all of these 
creatures imitate in such an extraordinary way, both in 
form and colouring, their floating habitat, and conse- 
quently one another, that we can well imagine their de- 
ceiving both the birds and the fishes. Among the most 
curious of the gulf-weed animals is the grotesque little 
fish, probably Anfennarius marmoratus, which finds 
its nearest English ally in the “fishing frog” (Lo- 
Dphius piscatorius), often thrown up on the coast of Britain 
and conspicuous for the disproportionate size of its head 
and jaws, and for its general ugliness and rapacity. None 
of the examples of the gulf-weed Axtennarius which we 
have found are more than 50mm. in length, and we are 
still uncertain whether such individuals have attained 
their full size. It is this little fish which constructs the 
singular nests of gulf-weed bound in a bundle with 
cords of a viscid secretion, which have been already men- 
tioned as abundant in the path of the gulf-stream, 
Scillea pelagica, one of the shell-less mollusca, is also” 
a frequent inhabitant of the gulf-weed, A little short 
. 
