FROM a comparative study of floras of the past, the palaeobotanist, especially if he is assisted by the enthusiasm of youth, expects to make some contribution towards a better understanding of the process of plant evolution. The fewer facts we possess, the easier it seems to fit them into a prearranged scheme; the larger the mass of material, the more difficult it becomes to interpret the conflicting testimony of many witnesses. Palaeobotanical research has thrown much light on the relative antiquity of certain genera and families; but it may also be said that the longer one studies the records of the rocks the problem of evolution assumes a more baffling complexity. In order to visualise the march of plant-life over the unstable surface of the earth, it is necessary to work out, so far as possible, the distribution of plants both in space and in time. The recent publication of a volume by Prof. Halle of Stockholm on a collection of fossil plants from northern China affords an exceptionally good illustration of the bearing of palaeobotanical research on problems of general biological interest. The memoir on the Palaeozoic plants from Central Shansi, published as a volume of the “Palaeontologia Sinica,” is appropriately dedicated to the memory of Alfred Gabriel Nathorst, whose post at Stockholm—the Mecca of palseobotanists and one of the very few places where the science has been deemed worthy of the status of a separate department—is now very ably filled by the author. Palaeontologia Sinica Ser A, vol 2, fasc 1: Palaeozoic Plants from Central Shansi. By T. G. Halle. Pp. 317 + 64 plates. (Peking: Geological Survey of China, 1927.)