fugiens sane Macrinus cum paucis et filio in vico quodam Bithyniae occisus est cum Diadumeno, ablatumque eius caput est et ad Antoninum perlatum.
Translation :
He did, indeed, escape from the battle together with his son and a few others, but he and Diadumenianus were afterwards slain in a certain village of Bithynia, and his head was cut off and carried to Antoninus.
Edition :
Historia Augusta, Volume II: Caracalla. Geta. Opellius Macrinus. Diadumenianus. Elagabalus. Severus Alexander. The Two Maximini. The Three Gordians. Maximus and Balbinus. Translated by David Magie. Loeb Classical Library 140. Cambridge, MA: Harvard University Press, 1924