  We analyze bilayer quantum Hall ferromagnets, whose underlying symmetry group
is SU(4). Spin-pseudospin coherence develops spontaneously when the total
electron density is low enough. Quasiparticles are CP^3 skyrmions. One skyrmion
induces charge modulations on both of the two layers. At the filling factor$\nu
=2/m$ one elementary excitation consists of a pair of skyrmions and its charge
is $2e/m$. Recent experimental data due to Sawada et al. [Phys. Rev. Lett. {\bf
80}, 4534 (1998)] support this conclusion.
