Analytical formulas including those for group and phase paths for radio rays in quasiparabolic (ionospheric) layers with spherical symmetry are presented in a convenient table. Their most important singularities are summarized in another table. By means of these formulas a transmission-slider technique is presented for the determination of the shapes of oblique ionograms. The phenomenon of low-angle cutoff is explained as well as the phenomenon of the trapping of waves. For a trapped wave it is shown that the group path between successive reflections is independent of the direction of the ray. The properties of rays in spherical layers are summarized, and some simple cases with nonspherical layers are discussed. In particular, a method is given for ray tracing in a wedge.