[en] The structure of isothermal configurations is investigated in the case of a partially degenerate semirelativistic (PD-SR) gas in the presence of radiation pressure but at an arbitrary constant temperature. For nonrotating configurations, an analytic continuum of solutions for intermediate temperature isothermal spheres is found which contains a number of previously known limiting cases. These include the nondegenerate semirelativistic gas sphere, the partially degenerate nonrelativistic (low temperature) and completely relativistic (high temperature) gas spheres, and the completely degenerate white dwarf sphere. Numerical solutions have been obtained, and results are presented for a number of physically interesting quantities for several combinations of central degeneracy and temperature. The mass-radius and limiting mass relations, previously known in the white dwarf limit, have been extended throughout the full span of completely relativistic configurations. Most significantly, however, the solutions and limiting forms presented here unite previous results obtained over the span of more than a century