From Dom Guéranger's The Liturgical Year.

Let us, in union with the Church, make a commemoration of Saints Simplicius and Faustinus, martyred in the persecution of Diocletian, together with their sister Viatrice, whose name was gracefully changed into Beatrice after she had gone to heaven. The sister had had time to bury her brothers; and after her own combat she was laid to rest beside them, by the last of the celebrated Lucina. The hour for the triumph of the Church had not yet arrived; nevertheless the tomb of this illustrious trio, in the very grove of the Dea Dia of the Arvales, proclaims the victory of Christ over the most ancient superstitions of Rome. The holy pontiff Felix, who shares the honours paid to this glorious company, suffered in the time of the Arians.

Prayer

Præsta, quæsumus Domine, ut sicut populus Christianus martyrum tuorum Felicis, Simplicii, Faustini, et Beatricis temporali solemnitate congaudet: ita perfruatur æterna; et quod votis celebrat, comprehendat effectu. Per Dominum.
Grant, we beseech thee, O Lord, that as thy Christian people rejoice together in the temporal solemnity of thy martyrs, Felix, Simplicius, Faustinus, and Beatrice, they may enjoy it in eternity, and may effectually attain to what they celebrate in desire. Through our Lord, etc.