mouth has the
appearance of being situated on its back; a fin, 0.4 inches in length,
projected directly out from one side of the fish, and there was every
appearance of a perfectly similar one having been torn from the other
side; a hard horny membrane projected from underneath the stomach of the
animal, being apparently a sort of fin.

Its colour was of a silvery metallic lustre, having in parts a burnished
appearance, except where it is shaded (see Illustration 5 and below) and
then it was of a dark green colour; the tail was perfectly transparent,
except just where it joined the body, and there, where the shaded line
is, it was dark green.

This fish was swimming about, apparently preying on the tentaculae of the
barnacles, of which there were numbers round the ship attached to the
dead Velella, some of which I had caught yesterday; it appears therefore
probable that its mouth was placed in so extraordinary a position to
enable it to seize this pendant prey.

We caught this day a number of Velella, which are furnished with crests;
some of them were dead, and nearly always when such was the case we found
a species of barnacle attached in great numbers to them. When these
animals had only recently died, so that the whole of their blue base had
not been detached from them, the barnacles were generally very minute, so
that the naked eye could only just detect them, and there were no large
barnacles on the same fish: now, how did the minute ones get there? As
the barnacles grew larger, the remains of the velella changed into large
excrescences, half the size of a walnut.

We caught also several little animals, all of the same species, which
swam about on the surface of the water with the greatest rapidity,
performing the same kind of evolutions that we see in a little black and
white insect (Gyrinus) which swims on the top of tranquil pools in
England.

July 16.

This day a curious animal was caught, perfectly diaphanous; total length
0.8 inch; length of third leg, 0.4 inch; this was provided with a claw
like a crab; head shaped like a grasshopper, 0.2 inch in length, and
placed like the head of a grasshopper, at right angles to the body; eyes
black and prominent, apparently four, two on each side; first and second
legs of nearly the same length; the third leg nearly double the length of
either of the others; five on each side. The top of the head is divided
into two prominent knobs, one on each side, which, viewe