Caligula inaugurated a tax upon prostitutes (vectigal ex capturis), as a state impost: "he levied new and hitherto unheard of taxes; a proportion of the fees of prostitutes;--so much as each earned with one man.

A clause was also added to the law directing that women who had practiced harlotry and men who had practiced procuration should be rated publicly; and furthermore, that marriages should be liable to the rate" (Suetonius, Calig.

xi).

Alexander Severus retained this law, but directed that such revenue be used for the upkeep of the public buildings, that it might not contaminate the state treasure (Lamprid.Alex.Severus, chap.

24).