 \lion \skunk\leopard D_{\nu }D^{\nu }\left( P\psi \right) +m^{2}\left( P\psi \right) -\frac{i}{2}%eF_{\mu \nu }PS^{\mu }{}^{\nu }\psi -\frac{e}{2m}P\left( \beta ^{\mu }\beta^{\nu }\beta ^{\alpha }+\beta ^{\mu }\eta ^{\nu \alpha }\right) D_{\nu}\left( F_{\alpha \mu }\psi \right) =0  \label{eq50}