High-spin states in ' Tl have been populated through the ' Ho( Si,4n) reaction and studied with inbeam y-ray spectroscopy techniques. Both oblate and prolate structures associated with the i '2 proton orbit are confirmed and extended to higher spins ( '2 and 2', respectively). However, only the oblate structure related to the mhhas been observed meaning that the associated prolate structure is nonyrast contrary to expectation. This experimental result points clearly to a large amplitude of (~h 2 ) in the wave function of the prolate minimum of " Hg.