—•———•
iv. INTRODUCTION.
that organic distribution depends on soil and climate; for we often find a perfect identity
of these conditions in opposite hemispheres and in remote continents, whose fauna? and
florae are almost wholly diverse. It does not imply that allied but distinct organisms
have been educed by generation or spontaneous development from the same original stock;
for (to pass over other objections; we find detached volcanic islets which have been ejected
from beneath the ocean, (such as the Galapagos for instance,) inhabited by terrestrial forms
allied to those of the nearest continent, though hundreds of miles distant, and evidently
never connected with them. But this fact may indicate that the Creator in forming new
organisms to discharge the functions required from time to time by the ever vacillating
balance of Nature, has thought fit to preserve the regularity of the System by modifying
the types of structure already established in the adjacent localities, rather than to proceed
per saltum by introducing forms of more foreign aspect. We need not, however, pursue
this enquiry further into obscurity, but will merely refer to the law of geographical distribution,
as bearing on the subject before us.
In the Indian Ocean, to the east of Madagascar, are three small volcanic islands, which,
though somewhat scattered, are nearer to each other than to any neighbouring land. This
circumstance gives them a claim to be regarded as a geographical group, a meagre fragment
of an archipelago, although in a general sense they are connected with Madagascar, and
more remotely with the African continent. In conformity with the above-mentioned relation
between geographical distribution and organic structure, we find that a small portion of
the indigenous animals and plants of those islands are either allied or identical with the
products of Africa, a larger portion with those of Madagascar, while certain species are
peculiar to the islands themselves. And as these three islands form a detached cluster, as
compared to other lands, so do we find in them a peculiar group of birds, specifically different
in each island, yet allied together in their general characters, and remarkably isolated from
any known forms in other parts of the world. These birds were of large size and grotesque
proportions, the wings too short and feeble for flight, the plumage loose and decomposed,
and the general aspect suggestive of gigantic immaturity. The history of these birds was
as remarkable as their organization. About two centuries ago their native isles were first
colonized by Man, by whom these strange creatures were speedily exterminated. So rapid
and so complete was then- extinction that the vague descriptions given of them by early
navigators were long regarded as fabulous or exaggerated, and these birds, almost
INTRODUCTION. 5
contemporaries of our great-grandfathers, became associated in the minds of many persons
with the Griffin and the Phoenix of mythological antiquity. The aim of the present work
is to vindicate the honesty of the rude voyagers of the 17th century, to collect together
the scattered evidences which we possess, to describe and depict the few anatomical
fragments of these lost species which are still extant, to incite the scientific traveller to
search for further evidences, and to infer from the data before us the probable rank of
these birds in the System of Nature.
These singular birds, which for distinction we shall henceforth designate by the
technical name Diditue, furnish the first clearly attested instances of the extinction of
organic species through human agency. It has been proved, however, that other examples
of the kind have occurred both before and since;1 and many species of animals and of
plants are now undergoing this inevitable process of destruction before the ever-advancing
tide of human population.2 We cannot see without regret the extinction of the last
individual of any race of organic beings, whose progenitors colonized the pre-adamite Earth;
but our consolation must be found in the reflection, that Man is destined by his Creator
to " be fruitful and multiply and replenish the Earth and subdue it." The progress of
Man in civilization, no less than his numerical increase, continually extends the geographical
domain of Art by trenching on the territories of Nature, and hence the Zoologist or Botanist
of future ages will have a much narrower field for his researches than that which we enjoy
at present. It is, therefore, the duty of the naturalist to preserve to the stores of Science
the knowledge of these extinct or expiring organisms, when he is unable to preserve their
lives; so that our acquaintance with the marvels of Animal and Vegetable existence may
suffer no detriment by the losses which the organic creation seems destined to sustain.
In the case of the Didina, it is unfortunately no easy matter to collect satisfactory
information as to their structure, habits, and affinities. We possess only the rude
1 As instances, I may mention the Census megaceros, or Irish Elk, and the Bos primigeiiius, or Urus, destroyed
in ancient, and the Rytina Slelleri, or Northern Dugong, in modem times.
-' Among animals whose doom is probably not far distant are the Bison prisms, or Aurochs, (preserved only
by imperial intervention in the Bialowicksa forest, whence the Czar has lately enriched the London Zoological
Gardens with n living pair); the Xes/or productus, (a Parrot originally from Phillip's Island near Norfolk Island,
where it is now destroyed, though a few individuals, which refuse to propagate, still survive in cages); the two
(not improbably three) species of Jp/eryu-; and the almost equally anomalous burrowing Parrot, S/riyops hubroptilus,
of New Zealand; &c.
C