Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
The senate passed over what had taken place
in silence, and ordained that the two surviving testamentary heirs
should have the kingdom equally divided between them, and that, for
the prevention of fresh quarrels, the division should be undertaken
by a commission of the senate.
This was done: the consular Lucius
Opimius, well known through his services in setting aside the
revolution, had embraced the opportunity of gathering the reward
of his patriotism, and had got himself placed at the head of the
commission.
The division turned out thoroughly in favour of Jugurtha,
and not to the disadvantage of the commissioners; Cirta (Constantine)
the capital with its port of Rusicade (Philippeville) was no doubt
given to Adherbal, but by that very arrangement the portion which
fell to him was the eastern part of the kingdom consisting almost
wholly of sandy deserts, while Jugurtha obtained the fertile
and populous western half (what was afterwards Mauretania
Caesariensis and Sitifensis).