492 Proceedings of the Royal Irish Academy. 
ut potiori placuerat Valentinianus Mediolanum Constantinopolim 
Valens discessit.” 
And then he adds :— 
‘* Et orientem quidem regebat potestate praefecti Sallustius, Italiam 
vero cum Africa et Illyrico Mamertinus, et Gallicas provincias Ger- 
manianus.”’ 
Thus in 865 there were only three prefects and three prefectures, 
Illyricum and Italia forming one, instead of two, as in later times. 
- It cannot be said that Illyricum merely means Pannonia and Dalmatia 
(the dicecesis of occidental Illyricum, as it was called in later times, 
when it formed one dioecesis of the Praefectura Italiae), and that 
Ammianus merely omits to mention the fourth prefect because he may 
have been a person of less importance. For in the first place we have 
no reason to suppose that Pannonia and Dalmatia were separated from 
the rest of the Balkan peninsula, and closely connected with Italy 
until 895 ; and, in the second place, Ammianus evidently intends a 
complete enumeration, as we can see if we consider why he introduces 
the remark in this place. It is evidently to be taken closely with the 
foregoing diviso palatio; the prefect of the Gauls, and the prefect of 
Italy, Africa, and Illyricum, were to be responsible to Valentinian— 
the prefect of the East to Valens. The division of the officers implied 
and determined the division of the empire. Ammianus does not ex- 
press this in so many words, but he does not leave it in any doubt, as 
he says that Valentinian’s capital was Mediolanum; that of Valens, 
Constantinopolis. Had there been a fourth prefect of Illyricum 
(Moesia, Dacia, Macedonia, and Achaia), and had Ammianus omitted 
him, he would have left his readers in doubt to which of the brothers 
Illyricum was assigned. 
The evidence of Ammianus is borne out by an inscription, which 
shows that Claudius Mamertinus had been praetorian prefect of Italy 
and Illyricum in the year 362-363. This inscription was found at 
Concordia, and contains the following words (C.1. L., v. 8987) :— 
‘‘Disponente Claudio Mamertino viro clarissimo per Italiam et 
Inlyricum praefecto praetorio.” 
Mamertinus is also mentioned in the Theodosian Code, De Vume- 
rarws, lex 8. 
But if it is certain that in the years 362-365 there were only three 
prefects, it is equally certain that immediately before Mamertinus there 
were four. Taurus was praetorian prefect of Italy from 354 to 361, as 
is proved by the laws in the Cod. Theod. But we know from Ammi- 
anus that Anatolius was praetorian prefect of Illyricum 859-860 
(xrx., 11, 2, “‘ Anatolio regente tune per Illyricum praefecturam’”’; and 
xxt., 6, 5, where his death, and the succession of Florentius, are 
recorded). In 861 both Taurus and Florentius, the successor of 
Anatolius, were superseded (cf. xxu., 8, 4, and 3, 6). Ammianus 
