of my islands' existence, indeed, a few stray feathered fowls of the
air were driven ashore here by violent storms, at a time when
vegetation had not yet begun to clothe the naked pumice and volcanic
rock; but these, of course, perished for want of food, as did also a
few later arrivals, who came under stress of weather at the period when
only ferns, lichens, and mosses had as yet obtained a foothold on the
young archipelago. Sea-birds, of course, soon found out our rocks; but
as they live off fish only, they contributed little more than rich beds
of guano to the permanent colonising of the islands. As well as I can
remember, the land-snails were the earliest truly terrestrial casuals
that managed to pick up a stray livelihood in these first colonial days
of the archipelago. They came oftenest in the egg, sometimes clinging
to water-logged leaves cast up by storms, sometimes hidden in the bark
of floating driftwood, and sometimes swimming free on the open ocean.
In one case, as I recall to myself well, a swallow, driven off from the
Portuguese coast, a little before the Glacial period had begun to
whiten the distant mountains of central and northern Europe, fell
exhausted at last upon the shore of Terceira. There were no insects
then for the poor bird to feed upon, so it died of starvation and
weariness before the day was out; but a little earth that clung in a
pellet to one of its feet contained the egg of a land-shell, while the
prickly seed of a common Spanish plant was entangled among the winged
feathers by its hooked awns. The egg hatched out, and became the parent
of a large brood of minute snails, which, outliving the cold spell of
the Ice Age, had developed into a very distinct type in the long period
that intervened before the advent of man in the islands; while the seed
sprang up on the natural manure heap afforded by the swallow's decaying
body, and clinging to the valleys during the Glacial Age on the
hill-tops, gave birth in due season to one of the most markedly
indigenous of our Terceira plants.