An essential part of this valuable work is the short incisive Preface in which Professor Wills warns all readers of the limitations of palaeogeographical maps and of the dangers of regarding them as anything more than reasonable guesses, to be improved upon with further knowledge. If the meaning of the Preface is grasped, any fear that the publication of the maps will do more harm than good may be dismissed.

Three maps illustrate the conditions which may have obtained during the Pleistocene glaciation. Plate XX shows the areas in Europe believed to have been covered by ice at different stages: the Ante-Penultimate, Penultimate and Last Glaciations (Zeuner’s classification). Plate XXI is based on the “Older Drifts” and gives the distribution and directions of ice movement of the Penultimate Glaciation in the British Isles. Plate XXII based on the Newer Drifts is an attempt to synthesize the work of many authors and to picture various stages of the Last Glaciation in the British Isles.

If, as has been well said, the trick of stimulating thought largely consists in inciting disagreement, these maps will prove most valuable. They are clear and easy to read, and brief notes draw attention to their salient features. We noticed only one slip—the expression “isostatic changes of sea-level.” Professor Wills is to be heartily congratulated on the production of the Atlas which will be a delight to all students of the Past.