Muratori (dissert. xlii. tom. iii. p. 785-788) has published an original treaty:
Concordia inter D. nostrum papam Clementem III. et senatores populi Romani super regalibus et aliis dignitatibus urbis, etc., anno 44° senatûs.
The senate speaks, and speaks with authority:
Reddimus ad præsens .... habebimus .... dabitis presbyteria .... jurabimus pacem et fidelitatem, etc.
A chartula de Tenementis Tusculani, dated in the 47th year of the same æra, and confirmed
decreto amplissimi ordinis senatûs, acclamatione P. R. publice Capitolio consistentis.
It is there we find the difference of
senatores consiliarii
and simple senators (Muratori, dissert. xlii. tom. iii. p. 787 - 789).