All measurements are in the metric system. In copied descriptions inches and hundredths have been carefully reduced to millimeters and the English measurements omitted, tenths and hundredths of millimeters being disregarded in most instances. In accordance with Canon XXXVII of the Code of Nomenclature adopted by the American Ornithologists' Union, Revised Edition (1908), generic and specific names, unless evidently misprinted, are spelled as in the original descriptions. Dr. Charles W. Richmond, Assistant Curator, Division of Birds, United States National Museum, has most kindly verified a very large number of these citations. The last half century has been exceedingly fruitful in systems of classification, some of them excellent, most of them suggestive and helpful. The whole subject has been reviewed in a masterly way by Newton, Dictionary of Birds, London (1896), 45-120 of introduction. The present author has not the ability to judge of the relative merits of the schemes of classification proposed by various authors but the system set forth in Sharpe's Hand-List [3] and copied in McGregor and Worcester's Hand-List of Philippine Birds is followed as being both convenient and well known. USE OF THE KEYS. A key is a short cut used to approximate identification without reading a great number of descriptions. The keys given here differ in no essential particular from those to be found in other systematic works on ornithology, but for the benefit of the beginner their use may be briefly explained. Having in hand an unknown bird begin with the key to the Orders (p. 7), reading first the line beginning a1; if the specimen has the characters given after a1 then the bird belongs to the Order Pelecaniformes and another key is to be used which will be found under that order, (p. 200). If the characters on the line after a1 are not found in the specimen, then those given on the line a2 are to be examined and these the specimen must have, if no mistake has been made. The next choice is between b1 and b2 and so on until characters are found which agree with those of the specimen and at the same time lead to a word at the right printed in heavy face type; this is the name of the order to which the specimen belongs. Having determined the order turn to the page where the order begins and use the key there which leads to the suborders or to the families, then find and use the keys to genera and species. To illustrate the use of keys with a concrete example, suppose that we have a specimen of the common spoon-billed duck or shoveler, but know nothing of its affinities. Beginning with the key to orders we find: "a1. Hind toe connected by a web to the inner toe." As this does not agree with our specimen we try: "a2. Hind toe not connected by a web to the inner toe." Yes. "b1. Nostrils tubular." No. "b2. Nostrils not tubular." Yes.