  Various types of galaxies observed in the cosmological scales show P-Cygni
type profiles in the Lyman alpha emission lines. A Monte Carlo code is
developed to investigate the Lyman alpha line transfer in an optically thick
and moving medium with a careful consideration of the scattering in the damping
wing. The main features in emergent line profiles include a primary emission
peak in the red part and a much weaker secondary peak in the blue part. The
primary peak recedes to the red and the width of the feature increases as
$N_{HI}$ increases. The P-Cygni type profile in the Lyman alpha emission line
of DLA 2233+131 ($z=3.15$) is noted to be similar to those found in the nearby
galaxies and distant ($3<z<3.5$) H II galaxies. Our numerical results are
applied to show that the DLA system may possess an expanding H I supershell
with bulk flow of $\sim 200 km/s$ and that the H I column density $N_{HI}$ is
approximately $10^{20} cm^{-2}$. From the observed Lyman alpha flux and
adopting a typical size of the emission region $\sim 1 \kpc$, we estimate the
electron density of the H II region to be $\sim 1 \cm^{-3} and the mass of H II
region $\sim 10^8 \msun$. We also conclude that it requires $\sim 10^3$ O5
stars for photoionization, which is comparable to first-ranked H II regions
found in nearby spiral and irregular galaxies.
