The whole of the large collection of birds secured by the Congo Expedition of the American Museum of Natural History during the years 1909 to 1915, under the leadership of Mr. Herbert Lang, has now arrived safely at the Museum. It is composed of material gathered all across the Belgian Congo, from Boma on the west to Aba in the northeastern corner, but the greater part from the more remote territory between Stanley Falls and the Enclave of Lado, including the dense equatorial forests of the Ituri, Nepoko, and Bomokandi, and the high-grass and bush country of the Uele District to the north and northeast.

Of the relatively small number of zoölogical expeditions that have passed through and collected in these regions, none has ever before been able to make such a prolonged stay, and the varied zoölogical results of this Expedition are surely of the highest scientific interest. The ornithological collection contains in the neighborhood of six thousand skins, and represents some 600 different species, a number of them of course new to science. These it is our purpose to describe as promptly as possible in this Bulletin, before taking up the greater work of a general report on all the forms collected, with more extended notes on their distribution, habits, food, and nests.