Observed spectra of the SS galaxies. The signal-to-noise ratio S/N = I_CO/error(I_CO) is indicated in the upper left corner. The velocity resolution is 20 km s⁻¹ for objects with S/N ≳ 7 and 50 km s⁻¹ for objects with S/N ≲ 7. The x-axis gives the velocity relative to the (optical) recession velocity, v_rec = cz, where z is the SLOAN redshift. The coloured shaded area represents the region over which the line is integrated to determine the total flux.