Pre-consecration Epiclesis
There follows the prayer: "Quam oblationem tu, Deus, in omnibus, quaesumus, benedictam, adscriptam, ratam, rationabilem, acceptabilemque facere digneris: ut nobis Corpus et Sanguis fiat dilectissimi Filii tui, Domini nostri Iesu Christi" (Be pleased, O God, wepray, to bless, acknowledge, and approve this offering in every respect; make it spiritual and acceptable, so that it may become for us the Body and Blood of your most beloved Son, our Lord Jesus Christ.)
Although this prayer does not mention the Holy Spirit, it is otherwise similar to an epiclesis, in which, usually, the Holy Spirit is invoked to effect the change of the bread and the wine into the Body and Blood of Christ. Accordingly, the 1970 edition of the Roman Missal directs the priest to extend his hands over the offerings while reciting it. In the Tridentine form of the Mass, the priest says the prayer with hands joined, except while making the five signs of the cross prescribed in that form of the rite.
From this pre-consecration epiclesis to the post-consecration epiclesis, inclusive, the words are spoken or sung by all the concelebrants together.
Read more about this topic: Text And Rubrics Of The Roman Canon