The neutral hydrogen west of lambda Orionis

The distribution of H I in the neighborhood of the two faint H-alpha filaments and loop near lambda Ori has been investigated. The pattern observed at velocities relative to the local standard of rest + 4.5, + 9.7, and, in part, + 15 km/sec suggests that the H I is associated with the optical filaments; but the proposed existence of a common expanding envelope of a relative thickness of about 0.6 is not confirmed.