arrivals and of the ordinary migrants--that is
to say, of those which have reached the country owing to accidental
distribution, and of animals which have adopted the usual course of
migration. It is of all the more import to review this subject of
accidental, or, as Darwin called it, "the occasional means" of
distribution, as both he and Dr. Wallace have, I venture to think,
somewhat over-estimated its significance. No one doubts that accidental
transportal takes place, but the question is whether the accidentally
transported animals arrive living and reach a spot where suitable food
is procurable, and whether they are able to propagate their own species
in the new locality. For it must be clear to anybody that the accidental
transportal of a beetle or of a snail to a new country cannot affect its
fauna or add one permanent member to it unless all these conditions are
fulfilled. As a matter of fact, only exceedingly few instances are on
record of man having witnessed, for example, the accidental transportal
across the sea to an island of a live animal.

To mention an example, Colonel Feilden informs us (_Zoologist_, 1888)
that, when living on the island of Barbadoes, an alligator arrived one
day on the shore, and at the same time a tree measuring 40 feet in
length, which was recognised as a Demerara species, was likewise
stranded. He thinks that there can be no doubt that the alligator, which
was alive when it reached Barbadoes, was transported by the tree, thus
covering a distance of 250 miles from the nearest land. Numerous
observations on the accidental transportal of seeds and tree-trunks from
one island to another, and from a continent to an island, have been
recorded, and even on our own shores we may witness the occasional
arrival of such vegetable products from a far distant land. On the west
coast of Ireland it not unfrequently happens that large West Indian
beans are stranded, and in this as well as in many other similar cases
the seeds have often proved none the worse for their prolonged immersion
in sea-water. That locusts are sometimes blown to great distances from
the land is not so surprising, since their power of steering through the
air is very limited. Darwin mentions (p. 327) having caught one 370
miles from the coast of Africa, and that swarms of them sometimes
visited Madeira. Sir Charles Lyell relates that green rafts composed of
canes and brush-wood are occasionally carried down the Parana River i