From left to right the saints Eustathius Placidus (half of him, see previous picture), Samonas and Gurias.

The two are often mentioned as a pair, and indeed I found the following: "The two friends Gurias and Samonas, preachers of the Word of God, were arrested in the city of Edessa. The saints refused to offer sacrifice to the gods, and boldly confessed their faith in Christ. For this they were subjected to cruel tortures: they were beaten, hung up by their hands, heavy weights were tied to their feet, and they were cast into a stifling prison. The martyrs endured everything with firmness […] By night, they took the martyrs out beyond the city and beheaded them (+ 299-306). Christians buried their holy bodies with reverence. "