m mouth, and
above with an obliquely vertical crest, the whole of a rich blue colour
with white lines and dots, the soft parts conceal a transparent
cartilaginous framework. The crest acts as a tiny sail (hence the name)
and communicates to the animal a slow rotatory movement while drifting
before the wind. Two kinds of Janthinae (J. globosa and J. exigua)
molluscs with a fragile, snail-like shell, and a vesicular float, were
drifting about, and, together with a very active, silvery-blue Idotea,
half an inch long, prayed upon the Velellae. At another time, among many
other pelagic crustacea, we obtained three kinds of Erichthus, a genus
remarkable for the glassy transparency of its species, also Hyalaea
inflexa and H. tridentata, curious pteropodous molluscs which swim near
the surface.

(*Footnote. Not having seen a description of this useful instrument, I
may mention that the kind used by Mr. Huxley and myself, consisted of a
bag of bunting (used for flags) two feet deep, the mouth of which is sewn
round a wooden hoop fourteen inches in diameter; three pieces of cord, a
foot and a half long, are secured to the hoop at equal intervals and have
their ends tied together. When in use the net is towed astern, clear of
the ship's wake, by a stout cord secured to one of the quarter-boats or
held in the hand. The scope of line required is regulated by the speed of
the vessel at the time, and the amount of strain caused by the partially
submerged net.)

ARRIVE AT SIMON'S BAY.

On March 8th, we anchored in Simon's Bay; our passage from Rio de
Janeiro, contrary to expectation, had thus occupied upwards of five
weeks, owing to the prevalence of light easterly winds (from north-east
to south-east) instead of the westerly breezes to be looked for to the
southward of latitude 35 degrees South. We were fortunate, however, in
having fine weather during the greater part of that time.

The period of our stay at the Cape of Good Hope was devoted to the
construction of a chart of Simon's Bay and its neighbourhood, which has
since been incorporated with the previous survey of Captain Sir Edward
Belcher in H.M.S. Samarang, and published without acknowledgment. The
requisite shore observations were made by Captain Stanley and Mr. Obree,
while Lieutenants Dayman and Simpson conducted the sounding. Our
detention was lengthened by a succession of south-east gales, and the
state of the weather throughout was such that during the period of
t