"the lion figure was used as a guardian .  .  . in a more abstract sense as a symbol of justice (CVSTOS JUSTICIE can be seen on the neck of the lion . . . at Bari) ."

Josef Deér,  The Dynastic Porphyry Tombs of the Norman Period in Sicily. Translated by G. A. Gillhoff (Dumbarton Oaks Studies, 5. Cambridge, Massachusetts: 1959) 67