[42] See _Eph. Ep._ v. 142, n. 1. The _ala_ is only known from x. 6011.
[43] The alae Flaviana, Petriana, Proculeiana, Tauriana, and Sebosiana all bear ‘Gallorum’ as a secondary title, and the alae Agrippiana, Longiniana, Picentiana, Pomponiana, and Rusonis seem to have been recruited in Gaul in the first century. The Gallic origin of the ala Atectorigiana is even more obvious. The ala Gallorum Indiana may possibly have a later origin, cf. Tac. _Ann._ iii. 42. The theory given above as to the origin of these regiments is unhesitatingly affirmed by von Domaszewski (_Rangordnung_, pp. 122, 123), but a little more evidence would certainly be advantageous.
[46] Von Domaszewski, in his edition, puts the treatise _De munitione castrorum_ into the reign of Trajan. It is difficult to regard the evidence as decisive, but there can be little doubt that the information contained in the work is in any case applicable to the period under discussion.
[47] Hyginus, 16. An Egyptian inscription, iii. 6581, also gives sixteen as the number of decurions in an ala.
[49] Von Dom. _Rangordnung_, p. 35, and also p. 52 of the same writer’s commentary on Hyginus.
[50] Arrian, _Tactica_, 18 αἱ δὲ δύο ταραντιναρχίαι ἱππαρχία, δώδεκα καὶ πεντακοσίων ἱππέων, ἥντινα Ῥωμαῖοι ἴλην καλοῦσιν. It is perhaps worth noting that Vegetius (ii. 14) gives 32 as the strength of a _turma_ of his _equites legionis_.
[51] The question will probably be found to turn on the strength of the _contubernium_. 30 and 42 suggest _contubernia_ of 6. A small _turma_ of 32 would suggest _contubernia_ of 8 or 4 and a large _turma_ of 40.
[52] Hyginus, 28 ‘Cohors peditata miliaria habet centurias X … item peditata quingenaria habet centurias VI, reliqua ut supra’. This refers to the description of the _cohortes equitatae_ in the preceding section in which it is stated that ‘Cohors equitata quingenaria habet centurias VI, reliqua pro parte dimidia’.
[53] Josephus, Bell. _Iud._ iii. 67 τῶν δὲ σπειρῶν αἱ δέκα μὲν εἶχον ἀνὰ χιλίους πεζούς, αἱ δὲ λοιπαὶ τρισκαίδεκα ἀν’ ἑξακοσίους μὲν πεζούς, ἱππεῖς δ’ ἑκατὸν εἴκοσι. Nissen, who accepts the authenticity of these figures, assumes that both types of cohort mentioned had 120 cavalry attached to them, but it seems impossible to get this meaning from the Greek. See his article on the history of Novaesium in _B. J. B._ cxi-cxii. 41.