The structure of high-energy solar proton penetration zones in the polar and subpolar regions using data from riometers, transpolar satellite DMSP-F6, and neutron monitors during an extremely anisotropic solar proton event on February 16, 1984, has been studied. Particular emphasis was placed upon interpretation of the solar proton intensity maximum located at the auroral and nearby latitudes. Precipitation of quasi-trapped particles drifting along the latitudinal direction from the entry site of the anisotropic flux at the dawnside of the magnetosphere is discussed as a cause of this maximum. ¿ American Geophysical Union 1993