In the past the study of various kinds of whistlers has provided valuable information on the structure of the magnetosphere. However, one type of whistler whose study has been somewhat neglected is the so-called 'subprotonospheric' (SP) whistler. Here the propagation paths of SP whistlers are studied and a number of their characteristics explained. It is shown that horizontal gradients in the ionosphere play an important role in the reflection of ELF waves at an altitude of about 1000 km. The variations in intensity between the various components of SP whistlers observed from satellites are explained by the presence or absence of these gradients. The several components of an SP whistler, received at a point in the ionosphere are associated with wave packets entering the lower ionosphere at different latitudes and traveling along different paths. Data from the Ogo 4 satellite are used to substantiate these explanations. A tone rising in frequency with time that is often seen with SP whistlers and proton whistlers is shown to be caused by the reflection of a downcoming SP shistler component near the ion cutoff frequency. This contradicts a previously published explanation of the rising tone as a stimulated emission. The characteristics of the rising tone are sensitive to the relative abundance of the various ions, while those of the SP whistler depend greatly on horizontal gradients in the ionosphere. The combination of the SP whistler and the riser has potential as a diagnostic probe of the plasma structure of the ionosphere.