The roll having been completed in this manner, the tribunes belonging to the several legions muster their men; and selecting one of the whole body that they think most suitable for the purpose, they cause him to take an oath that he will obey his officers and do their orders to the best of his ability. And all the others come up and take the oath separately, merely affirming that they will do the same as the first man. At the same time the Consuls send orders to the magistrates of the allied cities in Italy, from which they determine that allied troops are to serve: declaring the number required, and the day and place at which the men selected must appear. The cities then enrol their troops with much the same ceremonies as to selection and administration of the oath, and appoint a commander and a paymaster. The Military Tribunes at Rome, after the administering of the oath to their men, and giving out the day and place at which they are to appear without arms, for the present dismiss them. When they arrive on the appointed day, they first select the youngest and poorest to form the Velites, the next to them the Hastati, while those who are in the prime of life they select as Principes, and the oldest of all as Triarii. For in the Roman army these divisions, distinct not only as to their ages and nomenclature, but also as to the manner in which they are armed, exist in each legion. The division is made in such proportions that the senior men, called Triarii, should number six hundred, the Principes twelve hundred, the Hastati twelve hundred, and that all the rest as the youngest should be reckoned among the Velites. And if the whole number of the legion is more than four thousand, they vary the numbers of these divisions proportionally, except those of the Triarii, which is always the same.