Because of limited space, the selection of species for the 20 maps on this plate was confined principally to well-known mammals. The ranges, for the most part, indicate present and usual distribution: rare or occasional occurrences have not been shown. As there is still much to be learned about the fauna of parts of northern Canada, some range limits are hypothetical. Furthermore, it should not be assumed that all species may be found throughout their respective ranges as indicated on these maps - distribution within their broad ranges is frequently limited to particular but discontinuous habitats.