The partition of the subject matter of this report follows that of earlier reports. Drafts for individual sections or parts of such were contributed by C. Arpigny, L. Biermann, A. H. Delsemme, O. V. Dobrovolsky, L. Haser, G. Herzberg, B. J. Levin, Rh. Lüst, E. Roemer, V. Vanýsek, and K. Wurm. The overall editing was done by Mrs Rh. Lüst, V. Vanýsek, and the undersigned.
Before mentioning some of the more important developments it is noted that E. Roemer has continued to publish every few months short notes on comets in the Publications of the A.S.P. The annual reports in Quarterly Journal of the Royal Astronomical Society have been continued by B. G. Marsden and J. G. Porter.
Several collections of Russian papers have been published which give a survey of the work done in the U.S.S.R. The description of physical characteristics of comets which appeared from 1961— 1965 was continued by S. K. Vsehsvjatskij, who also completed a book on Nature and Origin of Comets and Meteoritic Matter.