The experimental B(E1) values of transition 7/27/2+(404) to or from 7/27/2-(523) in 161,163,165Ho and 163,165,167,169,171Tm reveal characteristic minima in both groups of isotopes. E1 transition matrix elements are calculated on the basis of a Nilsson model including recently-deduced values of the deformation parameters epsilon 2 and epsilon 4. If these theoretical epsilon 4 values are arbitrarily decreased by a constant value, an improved degree of agreement with experiment can be obtained.