  We present analysis of time-variable, shifted absorption features in far-UV
spectra of the unusual 49 Ceti debris disk. This nearly edge-on disk is one of
the brightest known, and is one of the very few containing detectable amounts
of circumstellar gas as well as dust. In our two visits of Hubble Space
Telescope STIS spectra, variable absorption features are seen on the wings of
lines arising from C II and C IV, but not for any of the other circumstellar
absorption lines. Similar variable features have long been seen in spectra of
the well-studied $\beta$ Pictoris debris disk and attributed to the transits of
star-grazing comets. We calculate the velocity ranges and apparent column
densities of the 49 Cet variable gas, which appears to be moving at velocities
of tens to hundreds of km s$^{-1}$ relative to the central star. The velocities
of the gas in the redshifted variable event in Visit 2 show that the maximum
distances of the infalling gas at the time of transit are about 0.05 to 0.2 AU
from the central star. A preliminary attempt at a composition analysis of the
redshifted event suggests that the C/O ratio in the infalling gas may be
super-solar, as it is in the bulk of the stable disk gas.
