**The structure of crystals**: This supplement is a summary of new X-ray structure determinations published during the past four years. As such it follows strictly the form used in Part II of the second edition of "The Structure of Crystals" and aims to include all new studies that lead at least to cell dimensions. In order to facilitate comparison, the figure numbers and paragraph designations are continuations of those in the book. As before, reference numbers, with the year in bold-face, apply to the appended bibliography. The grouping of compounds is identical with that previously used except that in the chapter covering the type RX 3 a separate table has been created for crystals of the composition Rx (mx2)y. The writer is indebted to R. B. Corey and K. Pestrecov for much help in making the illustrations and to A. A. Murtland for assistance in preparing the bibliography.
Rockefeller Institute for Medical Research New York, N. Y. February, 1935.
