Waterlogged conditions, common on archaeological sites in York (United Kingdom), enhance the preservation of osseous and keratinaceous materials (bone, ivory, antler, whalebone, hoof, horn, tortoiseshell, baleen). However the identification of these materials is difficult. The author discusses the general principles and method of identification of materials, and then each material individually. References is made to artifacts found on archaeological sites in York. An account of baleen and tortoiseshell working is included. Photographs, micrographs, references.