THIRTY years ago it might have been thought that the main forms of intrusive bodies in the North Atlantic Tertiary volcanic province were known. Then came the discovery by the Geological Survey of the cone-sheet and ring-dyke complexes, and now in a part of East Greenland very difficult of access Mr. L. R. Wager has had the good fortune to find, and, in association with Dr. W. A. Deer, the pluck and persistence to investigate, an intrusive mass which in form, composition and internal structure is unlike any hitherto known in the province. The work in the field and laboratory has been very thorough, and the results are now presented in a handsomely produced memoir which will be of absorbing interest to students of igneous rocks and doubtless a basis of lively discussion among them*.