  Corrections to meson/ground-state baryon scattering amplitudes in the 1/N_c
expansion of QCD have previously been shown to be controlled by the t-channel
difference |I_t - J_t| of isospin and angular momentum and by the change of
hypercharge Y_t. Here we derive the corresponding expressions in the original
scattering s channel, allowing for nonzero meson spin and nontrivial SU(3)
flavor quantum numbers, and provide explicit examples of the crossing relevant
for pi N --> rho N and K N scattering.
