The number of the PRAETORS varied under Augustus and his successors from ten to eighteen. Twelve, fourteen, fifteen, and sixteen are found at various times, and the final limit of eighteen was still maintaining itself in the time of Hadrian.[1723] The reason for this expansion of their numbers was their utility for the enlarged jurisdiction of the period. The Republican functions of the _praetor urbanus_ and the _praetor peregrinus_ continued, until those of the latter became extinct, perhaps soon after the conferment of citizenship on the whole Roman world by Caracalla (212 A.D.);[1724] while other praetors, were guides of the _quaestiones perpetuae_, until the disappearance of these commissions towards the close of the second century.[1725] But new spheres of extraordinary jurisdiction claimed the attention of others. Thus Claudius instituted two praetors for adjudication on trusts (_fidei commissarii_),[1726] Nerva one for the decision of cases arising between the _fiscus_ and private individuals (_fiscalis_),[1727] and Marcus Aurelius another for the granting, and perhaps for the control, of guardians (_tutelaris_).[1728] For a short time the administration of the _aerarium_ was also in the hands of praetors.[1729] Most of the specific functions, which the AEDILES had exercised during the Republic, now passed to other hands or were shorn of their importance. The history of the later Republic had shown how incompetent these officials were to exercise an adequate control of the market, and the _cura annonae_ passed to the Princeps and to the praefecture established by him. Their police functions were to a large extent absorbed by the praefecture of the city, but they still destroyed books condemned by the Senate,[1730] and attempted to carry out the sumptuary laws.[1731] The _cura urbis_ still entailed on them the duty of keeping clean the streets of Rome[1732] and a supervision over places of public resort.[1733] Much of their criminal jurisdiction must have lapsed with the disappearance of trials before the _comitia_, but they still retain a power of inflicting fines and seizing pledges—one which was limited and regulated during the reign of Nero[1734]—and the special civil jurisdiction of the curule aediles still continues.[1735]