The citizens included in the census list were collectively described as _classici_, and were spoken of as _locupletes_ and _assidui_, the latter word probably meaning people “settled on land,” “landholders,” as most of those originally enrolled in the _classes_ were.[295] The others were the children-begetting citizens (_proletarii cives_). The use of the census for purposes of taxation gave other names to this class. In contrast to the _assidui_, who were registered on their property, they were called _capite censi_ as being registered on their _caput_ or mere headship of a family; and further, when the incidence of taxation extended below the minimum census, they were spoken of as _aerarii_, because their participation in the burdens of the state was shown only by the payment of taxes (_aes_). The word _aerarii_ seems always to have denoted those outside the census list.[296] The cavalry was an adaptation of the old patrician corps of _equites_[297] to the new conditions. The six original centuries were preserved and consisted as before of Patricians;[298] they still bore the names of the ancient tribes, and were called respectively _Titienses_, _Ramnes_, _Luceres_, _priores_ and _posteriores_.[299] They continued to be known as the _sex centuriae_, or (after the centuries acquired voting power) the _sex suffragia_.[300] To these were added twelve new centuries (_centuriae equitum_), composed, like the _classes_, of Patricians and Plebeians. But, unlike the _classes_, they were not enrolled on a property qualification. This is explained by the fact that they are not a list of men qualified for service but actually in service, a standing corps selected by the king and whose expenses were largely defrayed by the state. In later times, each knight was on his entrance into the corps given the means wherewith to furnish himself with a pair of horses[301] (_aes equestre_), and also a regular sum of money for their support (_aes hordearium_), the latter money being defrayed by unmarried women and orphans, who were possessed of property but could not by the nature of the case be rated in the census.[302] Each of these centuries formed a troop of one hundred men under a _centurio_,[303] and these eighteen centuries of Roman knights with public horses (_equites Romani equo publico_) continued unaltered in numbers and (with the exception that the _sex suffragia_ ceased to be chosen from the Patricians) in character to the end of the Republic. Although no definite census was required for the class, it was probably chosen from the first from the richest and most distinguished citizens; for its permanent existence implies leisure. The class was not divided by age into _seniores_ and _juniores_, for an obvious military reason. They were all _juniores_, and probably young men, whose release from the centuries was granted as soon as age had impaired their efficiency for service.