For May 24th, Orthodox Churches on the Old Calendar commemorate the Saints listed on May 11.
Saints
Martyrs Meletius Stratelates, Stephen, John, and 1218 soldiers with women and children, including:
Serapion the Egyptian, Callinicus the former Magician, Theodore, Faustus, the women Marciana, Susanna, and Palladia, two children Cyriacus and Christian; and
Twelve tribunes: Faustus, Festus, Marcellus, Theodore, Meletius, Sergius, Marcellinus, Felix, Photinus, Theodoriscus, Mercurius, and Didymus — all of whom suffered in Galatia (c.138-161)[1][2][3]
Tomb of Sts. Donatian and Rogatian in the Basilica of Sts. Donatian and Rogatian. The tomb is empty, as the relics were transferred to Ostia in the twelfth century.
^The notation Old Style or (OS) is sometimes used to indicate a date in the Julian Calendar (which is used by churches on the "Old Calendar"). The notation New Style or (NS), indicates a date in the Revised Julian calendar (which is used by churches on the "New Calendar").
^"ELPIDIUS (12), ST. The first of the four recorded bishops of Atella in Campania cir. A.D. 400. Great sanctity and many miracles were attributed to him and to his brother St. Cyo a presbyter and his nephew St. Elpicius a deacon, both of whom also lived at Atella. St. Elpidius was buried at Salerno, and his festival was on May 24. Some suppose that he is an African refugee in the Vandal persecution."[11]
^C.H. ELPIDIUS (12). In: William Smith and Henry Wace. A Dictionary of Christian Biography, Literature, Sects and Doctrines. Volume II: Eaba-Hermocrates. London: John Murray, Albemarle Street, 1880. p.101.
(in Greek) Συναξαριστής. 24 Μαΐου. ECCLESIA.GR. (H ΕΚΚΛΗΣΙΑ ΤΗΣ ΕΛΛΑΔΟΣ).
Russian Sources
(in Russian)6 июня (24 мая). Православная Энциклопедия под редакцией Патриарха Московского и всея Руси Кирилла (электронная версия). (Orthodox Encyclopedia - Pravenc.ru).