  Optical spectra of the bright Type II-L supernova SN 1979C obtained in April
2008 with the 6.5 m MMT telescope are compared with archival late-time spectra
to follow the evolution of its optical emission over the age range of 11 to 29
years. We estimate an Halpha flux decrease of around 35% from 1993 to 2008 but
noticeable increases in the strength of blueshifted emission of forbidden
oxygen lines. While the maximum expansion of the broad ~6700 km/s Halpha
emission appears largely unchanged from 1993, we find a significant narrowing
of the double-peaked emission profiles in the [O I] 6300, 6364 and [O II] 7319,
7330 lines. A comparison of late-time optical spectra of a few other Type II
supernovae which, like SN 1979C, exhibit bright late-time X-ray, optical, and
radio emissions, suggests that blueshifted double-peaked oxygen emission
profiles may be a common phenomenon. Finally, detection of a faint, broad
emission bump centered around 5800 Angstroms suggests the presence of WC type
Wolf-Rayet stars in the supernova's host star cluster.
