by 'legati' of his own, to one of whom he would entrust a legion, and appointed some, but probably not all, of the tribunes, and Marius, it seems likely, did the same. [Sidenote: Numbers of the legion.] The normal number of a legion had been 4,200 men and 300 horse, but was often larger. [Sidenote: The pay.] The pay of a legionary was in the time of Polybius two obols a day for the private, four for a centurion, and six for a horse soldier, besides an allowance of corn. But deductions were made for clothing, arms, and food. Hence the law of Caius Gracchus (cf. p. 51); but from the first book of the Annals of Tacitus we find that such deductions long continued to be the soldier's grievance. Auxiliary troops received an allowance of corn, but no pay from Rome. [Sidenote: The engineers.] The engineers of the army were called Fabri, under a 'praefectus,' the 'Fabri Lignarii' having the woodwork, and the 'Fabri Ferrarii' the ironwork of the enginery under their special charge, [Sidenote: The staff.] and all were attached to the staff of the army, which consisted of the general and certain officers, such as the legati, or generals of division, and the quaestors, or managers of the commissariat. [Sidenote: The Cohors Praetoria.] One of the most significant changes that had sprung up of late years was one which was introduced by Scipio Aemilianus at Numantia--the institution of a body-guard, or Cohors Praetoria. It consisted of young men of rank, who went with the general to learn their profession, or as volunteers of troops specially enlisted for the post, who would often be veterans from his former armies. The term Evocati was applied to such veterans strictly, but also to any men specially enlisted for the purpose. [Sidenote: The equites.] It is probable that the equites no longer formed the cavalry of a legion, but only served in the general's body-guard, as tribunes and praefects, or on extraordinary commissions. The cavalry in Caesar's time appears to have consisted entirely of auxiliaries.