  Using deep two-band imaging from the Hubble Space Telescope, we measure the
color-magnitude relations (CMR) of E/S0 galaxies in a set of 9
optically-selected clusters principally from the Red-Sequence Cluster Survey
(RCS) at 0.9 < z < 1.23. We find that the mean scatter in the CMR in the
observed frame of this set of clusters is 0.049 +/- 0.008, as compared to 0.031
+/- 0.007 in a similarly imaged and identically analyzed X-ray sample at
similar redshifts. Single-burst stellar population models of the CMR scatter
suggest that the E/S0 population in these RCS clusters truncated their
star-formation at z~1.6, some 0.9 Gyrs later than their X-ray E/S0 counterparts
which were truncated at z~2.1. The notion that this is a manifestation of the
differing evolutionary states of the two populations of cluster galaxies is
supported by comparison of the fraction of bulge-dominated galaxies found in
the two samples which shows that optically-selected clusters contain a smaller
fraction of E/S0 galaxies at the their cores
