Authorities of the United States National Museum and The American Museum of Natural History generously permitted me to work at those institutions, using their specimens for comparative studies. Other specimens were borrowed from the Museum of Comparative Zoology, Rijksmuseum Van Natuurlijke Historie, British Museum (Natural History), and the Yale Peabody Museum. Dr. Alexander Wetmore, Herbert Deignan, and Charles Vaurie helped with some of the more difficult taxonomic problems. Specimens cited in this report are in the Bernice P. Bishop Museum, The University of Kansas Museum of Natural History, The University of Michigan Museum of Zoology, and the U. S. National Museum. Richard F. Johnston and Robert M. Mengel kindly read the manuscript and made many helpful suggestions. The latter re-read it and assisted with the editing. The most recent comprehensive work published previous to my preparation of manuscript for the present account was Smythies (1960) "The Birds of Borneo." This report is a partial result of field work supported by a grant from the United States Army Medical Research and Development Command, Department of the Army, to the Bernice P. Bishop Museum for research on ectoparasites of vertebrates. The contract numbers were DA-MD-49-193-62-G47 and G65. The Chapman Fund of The American Museum of Natural History met part of the cost of transporting, to and from the United States, specimens from North Borneo collected after I left there. METHODS While collecting at Quoin Hill, we used only guns in taking birds. At an area 12 miles north of Kalabakan, we supplemented the guns with mist nets in the primary forest. This method was excellent for taking rarely seen species. For example the thrush _Zoothera interpres_ was never seen in the field but was taken several times in mist nets. Another method of collecting was the use of native snares. Such snares were made of heavy nylon string tied to a sapling, held down by a nylon string attached to a treadle. When a bird stepped on the treadle, it tripped the snare and a loop closed about its feet, hoisting it aloft. To divert large ground birds and mammals into the snare, natives placed brush barriers along the top of a ridge for one or two miles. Animals were diverted by these barriers until they came to an opening; if they went through they usually tripped the trap. Pheasants and the large ground cuckoo were taken in this manner. NOTES ON ZOOGEOGRAPHY