It has been proposed that the opening of the Bay of Biscay occurred by rotation about a pole situated near Paris (50.0° N, 3.3° E) and not about the pole proposed by Bullard et al.(4) (43.6° N, 1.0° E). The rotation about the first pole results in strike-slip motion aIong the North Pyrenean fault during the pre-Upper-Cretaceous opening, while the rotation about the second pole results in compression there. The second rotation is not compatible with geological data(5) which indicates extension prior to Upper Cretaceous in the Pyrenean region. We wish to show how these two hypothetical rotations agree with the magnetic data of Williams and McKenzie(6). [NOT CONTROLLED OCR]