In a previous investigation of Co-doped ${\mathrm{PbWO}}_4$ and ${\mathrm{PbMoO}}_4$, the EPR data were attributed to ${\mathrm{Co}}^{2+}$ ions occupying tetrahedral W (or Mo) sites of $S_4$ symmetry. Several years ago, Blasse proposed that the interstitial octahedral sites in scheelites could be occupied by ${\mathrm{U}}^{6+}$ ions. After reexamination of the $g$ value and hyperfine-structure (hfs) data and from the $2D$ estimates, the case for interstitial site occupancy by ${\mathrm{Co}}^{2+}$ in these two scheelites can be made plausible. Although they are not conclusive, the optical data are compatible with this assignment.

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