a calm, by which we were detained two days on the Portuguese
coast, _Janthina fragilis_ and _exigua_, _Rhizophysa filiformis_, and
another species, were brought up. Many specimens of the _Janthina
exigua_ were found, the bladder-like mass of which was stretched out to
a great length, and bent into the form of a hook at the end. On the
outer side was observed a fleshy streak, bordered by a close row of
small paunches: these paunches, which were externally open, contained a
great quantity of brown atoms, apparently spawn, and evidently in
motion. With respect to the _Rhizophysae_, it has been discovered that
they are of the same genus as the _Physsophora_, the hard part being
torn away in the act of catching them; upon this occasion also, several
of these separated parts, still in motion, and bearing some resemblance
to salpas, were brought up, and accurately examined.

Off the Cape de Verd Islands, in addition to the _Exocoetus volitans_,
which abounds there, various specimens of the much larger _Exocoetus
exsiliens_ of Cuvier alighted on board our vessel. The latter species is
distinguished by the long black fins of the belly, and by its remarkably
large eyes, differing greatly from the species described by Gmelin under
the same denomination.

The calms near the Equator afford an abundant harvest to the zoologist,
the tranquil water presenting an immense variety of marine animals to
his view, and allowing him to take them with little trouble in a net.
The open woollen stuff used for flags offers the most convenient
material for making these nets, as it allows the water to run through
very quickly, and does not stick together. A short, wide bag should be
made of this stuff, which may be stretched upon the hoop of a cask, and
the whole fastened to a long, light pole. From the height on which we
stand above the water, it is impossible to perceive the smaller animals;
the best way therefore to catch these is, to hold the net half in the
water, as if to skim off the bubbles of foam from the surface; then,
after a few minutes, if the net is drawn out, and the interior rinsed in
a glass of fresh sea-water, one may frequently have the pleasure of
seeing little animals of strange forms swimming in the glass. In the
course of ten days, I obtained, in this way, thirty-one different
species of animals, among which was a small _Diodon_, eight small
crustacea of forms almost wholly unknown; a sea-bug (_Halobates
micans_); three spe