When, at a later date, the Roman armies were composed partly of Roman citizens and partly of Socii (allies from the rest of the Italian mainland), either Latini or Italici, it became the practice to marshal the Roman troops in the centre of the battle line and the Socii upon the wings. Armies of the middle republic would consist of two legions of Roman citizens and two legions of "ala", with the ala supplying thirty turmae of cavalry per legion, whereas the Roman provided only ten turmae. Hence ala and alarii denoted the contingent furnished by the allies, both horse and foot, and the two divisions were distinguished as dextera ala (right wing) and sinistra ala (left wing) (Livy, xxvii.2 [1], Livy, xxv.21 [2], Livy xxxi.21 [3]; Lips. de Milit. Rom. ii. dial. 7. We find in Livy x.40 [4], th