  The properties of the MoSr2RCu2O8 (R=rare earth) system are found to
systematically change with the contraction of the R ions. For the light R ions
(La-Nd) the samples are paramagnetic down to 5 K, whereas in the intermediate
range (Sm-Tb), the Mo sublattice orders antiferromagnetically at TN, ranging
from 11 to 24 K. For the heavy R ions, Ho-Tm and Y, superconductivity appears
at TC in the range 19-27 K and antiferromagnetism sets in at TN < TC. This
latter behavior resembles most of the magneto-superconductors, but is in sharp
contrast to the iso-structural RuSr2RCu2O8 system where TN > TC.
