  We present visible spectra of Ag-like ($4d^{10}4f$) and Cd-like
($4d^{10}4f^2$) ions of Ho (atomic number $Z=67$), Er (68), and Tm (69)
observed with a compact electron beam ion trap. For Ag-like ions, prominent
emission corresponding to the M1 transitions between the ground state fine
structure splitting $4f_{5/2}$--$4f_{7/2}$ is identified. For Cd-like ions,
several M1 transitions in the ground state configuration are identified. The
transition wavelength and the transition probability are calculated with the
relativistic many-body perturbation theory and the relativistic CI + all-order
approach. Comparisons between the experiments and the calculations show good
agreement.
