detrimental to its general diffusion. No sensible naturalist will risk his fame, by giving his observations to the world, without knowing what has been done by those who have preceded him;--until, in fact, he has proper materials to work upon. He knows that these sumptuous authors should be consulted; he has not the means of so doing; and he relinquishes his purpose in despair. Such has been the result in two or three instances which I could mention: and the power of materially extending the bounds of science is thus confined to those favoured few, who are so fortunate as to possess, or to have the power of consulting, those splendid publications. The second objection is well grounded; but in whatever degree it may apply elsewhere, I trust the following pages will evince my anxiety to render the work replete with subjects hitherto unknown or unrecorded; and my own collections, in most cases, have given me ample means for examining and comparing both the genera and species of nearly all the subjects I have attempted to illustrate. In several instances my opinions will be found to differ from those of many celebrated naturalists of the day; but I have endeavoured to put the reader in possession of the reasons which have led to the conclusions I have adopted. This is but justice towards those who have preceded me, and to the great body of naturalists, by whom such questions will ultimately be decided. The age is past wherein the _ipse dixit_ of a great name was enough to check all inquiries after truth. Assertions must now be proved before they are admitted: and those writers who lay before the public tribunal of science their facts, their arguments, and their deductions, can alone hope to have their opinions generally adopted. The third and last objection is as new as it is singular; and has been urged against Miscellanies in general by an anonymous French writer.[1] However an author may feel annoyance or disappointment, that another should be the first to publish discoveries, which _he_ fancies belong exclusively to himself, he surely has no title to complain. The field of Nature is open to the inquiries of all. In her domain there are not yet established any _scientific preserves_.[2] If occupation or indolence does not permit _one_ labourer to make known his discoveries, is _another_ (who perhaps unconsciously has been working on the same ground) to hide the knowledge _he_ has gained? This is surely a principle at once illiberal and unjust. At this time, there is not perhaps a single department of Zoology which is not employing the attention of more than one writer. It is to the honour, and to the lasting benefit of science, that it should be so: and although a great part of the new objects collected during my travels in Europe and Brazil have recently been made public by MM. Temminck and Godart, I feel rejoiced that this has been done by such distinguished men.