The mountain-finches may be regarded as pointing first to the rock-sparrows (Petronia) and then to the true sparrows (Passer); while the grosbeaks pass into many varied forms and throw out a very well marked form - the bullfinches (Pyrrhula).
The second class, referred to in inscriptions by the name of praefecti ab decurionibus creati lege Petronia, seem to have been appointed by the local senate in case of a complete absence of higher magistrates, such as would have led in Rome to the appointment of an interrex.
Already in the time of Nero the magistrates had been ordered to receive the slave's complaint of ill-treatment; and the lex Petronia, belonging to the same or an earlier period, forbade masters to hand over their slaves to combats with wild beasts.
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