Xanton Cassius felix capitulo de erispila.
Xanton ABC fp | Xanthon e | Xancon j
erispila ABC jp | erispilla ef
Xanton is mentioned in Cassius Felix’s chapter De erispila.
Simon is here introducing the Greek adjective ξανθός /xanthós/, which is according to LSJ "yellow, of various shades, freq. with a tinge of red; brown, auburn". But he must have made a mistake when quoting his source. Although Cassius Felix in his De medicina, 24, ed. Fraisse (2001: 48). Ad ignem sacrum, speaks of fel flavum quam Graeci xanthen cholen vocant, yellow bile "which the Greeks call χολὴ ξανθή /kholḕ xanthḗ/"(i.e. Greek also meaning "yellow bile"), it is unlikely that Simon thought of this unremarkable occurrence of xanthen for his entry.
Most likely he is referring to chapter 20, 5, ed. Fraisse (2001: 38) Ad fistulas, where Cassius says: Sed si forte callositas minime fuerit secuta, etiam et xantou medicamenti partes duas mittes … , "But if by chance the hard skin does not go away, you should also lay on two parts of xanton medicamentum …" Anne Fraisse comments on xanton medicamentum, (2001: 38, annotation 141), saying this expression seems to allude to the yellow plasters (κιῤῥαί /kirrhaí/) mentioned by Galen, ed. Kühn (1821-33: XIII.520) with special indication for the treatment of fistulas (XIII, 520K.). xanton medicamentum is in fact a copper-based preparation that has been boiled for a long time.
Erispila is the somewhat corrupted form of ἐρυσίπελας /erysípelas/, adopted into Latin as erysipelas, and often referred to as St. Anthony's fire, i.e. a reddish skin eruption.