  Tunnel splitting oscillations in magnetic molecules are reconsidered within
the simplest model for the problem, which does not contain fourth order
anisotropy. It is shown that at large magnetic field, there is only one
instanton, and it is continuous. This is in contrast to the discontinuous
instantons that are induced by the fourth order term [Ersin Ke\c{c}ecio\u{g}lu
and A. Garg, Phys. Rev. Lett. {\bf 88}, 237205 (2002)].
