The surface wave evolution in a waveguide with a plasma column upon changing the external longitudinal magnetic field from 0 to infinity is investigated. It is shown that a family of anisotropic plasma modes EHl1ap exists when the magnetic field has intermediate values. When Omega < omega p (where Omega is the cyclotron frequency and omega p the plasma frequency), the EHl1ap modes have a surface wave field distribution. When Omega > omega p, they exist only for some system parameters and their field distribution has a quasi-surface character and when kz to infinity (where kz is the longitudinal wave number), the fields have a volume wave distribution.