  New experimental measurements are used to test model independent sum rules
for charmed baryon masses. Sum rules for medium-strong mass differences are
found to be reasonably well satisfied with increasing accuracy, and the new
measurements permit an improved prediction of $2778\pm 9$ MeV for the mass of
the $\Omega_c^{*0}$. But an isospin breaking sum rule for the $\Sigma_c$ mass
splittings is still in significant disagreement posing a serious problem for
the quark model of charmed baryons. Individual $\Sigma_c$ mass splittings are
investigated, using the new CLEO measurement of the $\Xi_c^\prime$ mass
splitting, but the accuracy is not yet sufficient for a good test.
