I opened the stomachs of several, and found them largely distended
with minced sea-weed (Ulvae), which grows in thin foliaceous
expansions of a bright green or a dull red colour. I do not
recollect having observed this sea-weed in any quantity on the
tidal rocks; and I have reason to believe it grows at the bottom of
the sea, at some little distance from the coast. If such be the
case, the object of these animals occasionally going out to sea is
explained. The stomach contained nothing but the sea-weed. Mr.
Bynoe, however, found a piece of a crab in one; but this might have
got in accidentally, in the same manner as I have seen a
caterpillar, in the midst of some lichen, in the paunch of a
tortoise. The intestines were large, as in other herbivorous
animals. The nature of this lizard's food, as well as the structure
of its tail and feet, and the fact of its having been seen
voluntarily swimming out at sea, absolutely prove its aquatic
habits; yet there is in this respect one strange anomaly, namely,
that when frightened it will not enter the water. Hence it is easy
to drive these lizards down to any little point overhanging the
sea, where they will sooner allow a person to catch hold of their
tails than jump into the water. They do not seem to have any notion
of biting; but when much frightened they squirt a drop of fluid
from each nostril. I threw one several times as far as I could,
into a deep pool left by the retiring tide; but it invariably
returned in a direct line to the spot where I stood. It swam near
the bottom, with a very graceful and rapid movement, and
occasionally aided itself over the uneven ground with its feet. As
soon as it arrived near the edge, but still being under water, it
tried to conceal itself in the tufts of sea-weed, or it entered
some crevice. As soon as it thought the danger was past, it crawled
out on the dry rocks, and shuffled away as quickly as it could. I
several times caught this same lizard, by driving it down to a
point, and though possessed of such perfect powers of diving and
swimming, nothing would induce it to enter the water; and as often
as I threw it in, it returned in the manner above described.
Perhaps this singular piece of apparent stupidity may be accounted
for by the circumstance that this reptile has no enemy whatever on
shore, whereas at sea it must often fall a prey to the numerous
sharks. Hence, probably, urged by a fixed and hereditary instinct
that the shore is its place of safety, whatever the emergency may
be, it there takes refuge.
During our visit (in October) I saw extremely few small individuals
of this species, and none I should think under a year old. From
this circumstance it seems probable that the breeding season had
not then commenced. I asked several of the inhabitants if they knew
where it laid its eggs: they said that they knew nothing of its
propagation, although well acquainted with the eggs of the land
kind--a fact, considering how very common this lizard is, not a
little extraordinary.