PREFACE. 
A^ien we began this work six years ago, we were under the impression 
that it would not be premature to write “The Birds of Celebes”, but the further 
we proceeded, the more we became aware how impossible it is at present to give 
a complete history of the species, as many undoubtedly still remain to be discov- 
ered in the interior and the mountains , not to speak of the islands ; and in 
the case of others whose names are familiar to ornithologists, we encountered a 
great lack of knowledge touching their local distribution, their subtile variations 
— individual, geographical , seasonal, sexual, and developmental, — their move- 
ments or, as the case may be, migrations, with the questions bearing thereon of 
seasons, climate, flowering of plants, ripening of fruits and the like, their nidifica- 
tion and moulting, habits and economy. We, therefore, are conscious of the imper- 
fection of our work and shall be entirely satisfied if it be useful to future workers 
on the Celebesian Avifauna, not doubting that a classical work could be ultimately 
written on the subject, of the standard of Naumann’s “Vogel Deutschlands” in 
12 volumes. 
The principles of nomenclature are now again in process of development and, 
consequently, unsettled; it is impossible to meet with the approval of every one 
in this respect. Our endeavours to give nomenclatory expression to the minute 
variations of groups of individuals not yet formed into species or subspecies led 
us to adopt an innovation discussed on pp. 52, 53 and elsewhere in the text; we 
anticipate that ere long this will be superseded by something better, and only regard 
it ourselves as a first step towards indicating those minute complex variations of 
a species within itself, which occur in Nature and are of such great importance 
in the study of evolution. 
In our synonymy an attempt at completeness has rarely been made, except 
in the case of endemic Celebesian birds; and, instead of an aimless repetition of 
the fuller synonymies in, for instance, the “Catalogue of Birds” and the “Ornitologia 
