of temperature.

3. They have no means of warming themselves by exercise or motion.

4. The species of food which they subsist on is confined to the latitudes
in which they themselves live.

5. They would have to traverse great distances in ungenial climes, and
contend against adverse winds, the children of placid seas and genial
suns hurried into giant waves and chilling storms.

6. It is not probable that they are swept along in currents, from the
circumstance that in the one which flows along the coast to the eastward
of the Cape we could find none of them, whilst upon its very edge they
were in abundance.

Could however their eggs be swept along by a current, and after having
been wave-tossed for months or years, be at last borne into waters
sufficiently warm to hatch them, and the animals, finding themselves in a
genial climate, have increased and multiplied?

The numerous little animals of the species which I have always considered
to be the Velella of Lamarck went sailing merrily by us today; the least
breath of wind made them turn round and round; and this was their mode of
progression, the animal moved its little sail which I have before
mentioned, and worked its tentaculae so vigorously as to make ripples in
the water, in the midst of which it went buoyantly floating along.

Caught another fish (Stenopteryx Illustration 5) of the same species as
that found on the 15th of July. The accompanying figure is drawn from
minute measurements. The length of this specimen was 2.5 inches, its
thickness through the thickest part 0.38.

What I had before imagined to be either a spine or fin turned out to be a
pectoral fin.

It thus has two pectoral, one dorsal, and one ventral fin, properly
speaking; but the greater part of the body is surrounded by some
cartilaginous substance which it probably uses as a fin; under the line b
c there is a curved portion of this matter, and above and attached to the
fish is a line of round white silvery scales, about ten in number.

Between a and b there is another curved mass of transparent cartilaginous
substance, along the bottom of which runs a spine to which is attached a
fringe-like fin. There is a spine upon the back; the eye is very
prominent and bright; upon the back, between the eye and the spine, there
are successive stripes of purple and burnished gold, so that this little
animal is one of the most gorgeously coloured denizens of the ocean. It
swims about amongst the