To the lower group, the _immunes_, belong the _signifer_, _custos armorum_, and _curator_ attached to every turma,[91] the _cornicularius_,[92] _actarius_,[93] _strator_,[94] _stator_,[95] _librarius_,[96] and _beneficiarius_,[97] who form the clerical and administrative staff of the _praefectus_, and his escort, the _singulares_.[98] In determining the position of the holders of these posts among the _immunes_ we are supported by the analogy of the Equites Singulares Imperatoris, a corps modelled upon and to a certain extent recruited from the auxiliary cavalry. The list of a _turma_ of this regiment contained on a Roman inscription gives the following arrangement:[99] nomina turmae Iul(ius) Mascel(lus) dec(urio) Nonius Severus dup(licarius) Iul(ius) Victorinus sesq(uiplicarius) Aur(elius) Mucatral Aur(elius) Lucius Ael(ius) Crescens sig(nifer) Aur(elius) Victor arm(orum custos) Aur(elius) Atero cur(ator) Ael(ius) Victor bf (beneficiarius) Cl(audius) Victorinus lib(rarius) Iul(ius) Vindex bf (beneficiarius) 17 names of equites follow. The fact that two privates occupy the fourth and fifth places shows clearly that the holders of all the posts mentioned lower in the list belong to the _immunes_. Had it not been for this piece of evidence we might have been tempted to place the _signifer turmae_ in the higher category. The analogy of the Equites Singulares also suggests that we may include the _bucinator_ and _tubicen_ among the _immunes_ of the ala,[100] and we have also to add the _medicus_, whose somewhat exceptional position is discussed later.[101]