I. Introductory. The work on which the following paper is based has been rendered possible only by the help received from many botanists. If it were not for a considerable private collection of seeds and fruits, mounted for microscopic examination, it would have been impracticable, either to gain the knowledge requisite for carrying out, the work, or to make the preliminary determinations, which are necessary before it is possible to use the great collections of our public herbaria. The formation of this collection of seeds, though initially, and essentially, due to my late husband's careful and unwearying labour, has for some years passed the bounds when the work of any single collector could meet the demands of the study of fossil seeds. Help has, however, been received from all sides: by gifts of specimens from Kew (both the Gardens and the Herbarium), the British Museum, the Herbarium of the Muséum d'Histoire Naturelle, Paris, and the Gardens of La Mortola; also by contributions from botanical friends, among whom I would especially mention Mr. James Groves, Mr. C. E. Salmon, Mr. T. A. Dymes, M. Émile Gadeceau, M. J. Simon, and Dr. Tokotaru Ito. As well as for contributions to my collection, I would also thank the officers of Kew and the British Museum, for their unfailing kindness in helping while I have been at work in the respective Herbaria, and in lending specimens for photography and study. Of late my work has been greatly furthered, particularly the photographic part of it,