In the Preface to Part IV. it was stated that Part V. would include the ferns and their allies and also the Musci and Hepaticae. The addendum to the Parts already published had grown so large, however that it was thought better to change our expressed intention, and in the Part now issued - which completes Volume II. - we include an addendum bringing the Parts already published up to date. Part VI. will be published during the ensuing year, and it will include the Characeae, Musci, and Hepaticae, about 1000 species in all.

Since the publication of Part IV., we have made collections on Prince Edward Island, and on the mainland of British Columbia, as far east as the summit of the Gold .Range; Dr. G. M. Dawson collected in British Columbia in 1888-9, and Jas. M. Macoun on the Athabasca, Clearwater, and Upper Churchill rivers in 1888, the results of these collections have been embodied in this Part. A number of collectors whose names will appear in the addendum have assisted me with notes and specimens, and to them hearty thanks are returned, and it is hoped that they and others will continue the good work. Communication has been kept up with specialists both in Europe and America, and the addendum will show the good results obtained.

Dr. Sereno Watson has examined many critical species, and has been of great assistance in many instances. Dr. N. L. Britton, of Columbia College, New York, has critically examined numerous genera, and is at present at work on others. Prof. Trelease, Director of the Shaw School of Botany, St. Louis, has examined our Geraniaceae and various difficult genera, and Professors Coulter and Rose the whole of our Umbelliferae, adding many new species and changing considerably the nomenclature. Mr. M. S. Bebb, of Rockford, Ill., has examined all our Willows and revised the nomenclature, much of that part of the addendum referring to the Willows being his work. Messrs. Bennett and Beeby have continued their work, and named our Potamogetons and Spargania. We have been enabled to make, the changes in, and additions to, the genus Carex, by the use of Prof. Bailey's Memoir, published by the Torrey Botanical Club, and by his examination of our specimens collected during the past two years. Prof. F. Lamson Scribner has determined all the grasses collected in British Columbia in 1889, and other critical species. The changes and additions in the order Gramineae, are either his or have been made at his suggestion. Dr. T. J. W. Burgess, our highest authority on Canadian Ferns, has prepared the orders Ophioglossaceae and Filices.

John Macoun.

Ottawa, May, 1880.