Pompeo Battoni
Christ with Saints Julian, Basilissa, Celsus and Marcionilla

1736-37
Oil on canvas, 64 × 34.9 cm. (25 3/16 × 13 3/4 in.)
The Getty Museum, Los Angeles, object 69.PA.3

The Getty website identifies the figures in the lower register: left to right are Julian and Basilissa (sharing a single lily stalk), Celsus, and Marcionilla. All four have palm branches to signify their martyrdom, but the lily stalk is the only other attribute.

Read more about images of these four saints.

Source: this page at Wikimedia Commons.