the optical and radio images. Our results are compatible with those by Massi et al. (1997), who found molecular gas linked to this dust cloud with velocities in the range \[$-$11.5,$-$6.5\]  (the South-Eastern Complex, S.E.C). At least four high density molecular cores listed by @russ10 are projected onto this dust column. For the two most massive cores (\#112 and \#115 in their table 2) these authors find velocities of –5.19 and , compatible with the velocity of cloud B. The fact that the borders of the dust cloud are ionized, the presence of PAH emission at 8 $\mu$m adjacent to the ionized gas [**(see Fig. 7)**]{}, and the existence of molecular gas in the region, clearly indicates that molecular gas is beeing photodissociated by the UV photons of Pis24.

As pointed out by @massi97, the fact that the molecular gas linked to the dust cloud has velocities more negative than the CO associated with Shell A gives additional support to the suggestion that the dust cloud (and Cloud B) is in front of the shells. Consequently, both ionized shells may be one structure ionized by the UV photons of some of the massive stars in Pis24 and swept-up by the 