To the casual observer Ontario appears as an immense territory, stretching from west of the Great Lakes to the St. Lawrence, and from Hudson Bay to the southernmost tip of Lake Erie. The naturalist sees more than this vastness: he is aware of the province's great diversity in flora and fauna, and in geology and topography; he sees the province divided into zones and regions, each with its own special natural traits. Over the years some areas, and their special attractions, have become widely known to naturalists, amateur and professional. Others have not been so familiar. It has been difficult for visitors to and residents of Ontario to plan well-arranged trips which will include a number of them. A guide to Ontario, designed specifically for naturalists, has been needed, and this book will fill that need. The combination of scientific accuracy and up-to-date practical information will make it an invaluable part of the naturalist's field equipment. Along with maps and general descriptions of the flora, fauna, and geology of Ontario, this book contains over forty regional guides. Each guide lists, concisely and accurately, up-to-date information on how best to reach the regions that are of interest to the naturalist. There are also descriptions of the geology, plants, trees, birds, and mammals typical of each locale, along with information on rare or unique species, and information on local naturalists and nature clubs. Indexes of place names and names of species, and a list of reference manuals, complete the contents of this unique and valuable guide. It will be equally useful to those who pay occasional weekend visits to the countryside, and wish to know something about the rocks, plants and wildlife they encounter, and to the more serious student of natural history. The guide has been prepared by members of the Federation of Ontario Naturalists and other allied agencies in the hope that it will help encourage a wider appreciation of natural history in Ontario. Sylvia Hahn's attractive drawings indicate some of the great variety of plant and animal life to be found in the province.