PREFACE.

HAvING brought this my second Monograph to a close, I am led to hope that my
labours in the elucidation of a tribe of birds hitherto involved in much confusion, will
not be destitute of some degree of value, more especially in the eyes of ornithologists,
introducing to their notice as it does many new species, and clearing up the difficulties
with which many of those even common in our cabinets have been previously sur-
rounded,—difficulties arising from several causes, among which may be enumerated the
differences in plumage, which obtain so often between the males and females, as well
as between the young males and the adults of the same sex, in some of the minor
groups; to which may be added the circumstance of the subject not having been at-
tempted by naturalists possessing command of those ample resources necessary for extri-

cating the subject from the labyrinth of confusion in which it has long been involved.

It would be presumptuous in me to say that this monograph is fully completed, or
that I have figured every existing species; on the contrary, I have reason to believe
that many will yet be discovered, both in the Old and New World, particularly in
those remote regions which civilized man has seldom, if ever, visited: but in order to
render the work complete up to the present time, I have not only done my utmost to
add every species to my own collection, bat have visited all the principal Museums of
Europe, both public and private, and, as in previous instances, have experienced the
greatest kindness and cooperation from the various eminent naturalists, private indivi-

duals, and the officers of the natural history department of every public institution.