Within Historical Times, No Signs
Of Volcanic Activity Have, I Believe, Been Manifested In Any
Part Of St. Jago.
Even the form of a crater can but rarely
be discovered on the summits of the many red cindery hills;
yet the more recent streams can be distinguished on the
coast, forming lines of cliffs of less height, but stretching
out in advance of those belonging to an older series:
The
height of the cliffs thus affording a rude measure of the age
of the streams.
During our stay, I observed the habits of some marine
animals. A large Aplysia is very common. This sea-slug
is about five inches long; and is of a dirty yellowish colour
veined with purple. On each side of the lower surface, or
foot, there is a broad membrane, which appears sometimes
to act as a ventilator, in causing a current of water to flow
over the dorsal branchiae or lungs. It feeds on the delicate
sea-weeds which grow among the stones in muddy and shallow
water; and I found in its stomach several small pebbles,
as in the gizzard of a bird. This slug, when disturbed, emits
a very fine purplish-red fluid, which stains the water for the
space of a foot around. Besides this means of defence, an
acrid secretion, which is spread over its body, causes a
sharp, stinging sensation, similar to that produced by the
Physalia, or Portuguese man-of-war.
I was much interested, on several occasions, by watching
the habits of an Octopus, or cuttle-fish.
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