Among the spirit specimens of mammals in the United States National Museum are several of the Chinese black finless porpoise, Neomeris phocaenoides (Cuvier), which were presented to the Museum by the National Geographic Society in collections made by F. R. Wulsin. Certain osteological features of one of these porpoises were investigated by Remington Kellogg in connection with another problem and his dissections indicated that unless some immediate use were made of these specimens they would soon be worthless for any studies of the soft parts. The matter was brought to the attention of Gerrit S. Miller, jr., and he generously permitted the writer to make whatever disposition of the material might seem to him best. It was at first thought that the preservation was too poor to permit of a dissection sufficiently accurate to be of great value, but it was later found that although the condition was far from satisfactory and such as to preclude fine work, observations of decided interest were nevertheless being made upon the first specimen which was being somewhat hastily examined, and in consideration both of the rarity of this porpoise in the collections of the world and the place in the research program of the writer of the investigation of aquatic adaptations, it was decided that these should be presented in print. A more careful and detailed dissection of a second specimen was accordingly undertaken by the author, and upon this the present contribution is based.