Evidence in support of this conjecture, which is, as we have seen, lacking in the writings of Caesar and his continuators, has been sought for elsewhere. The majority of Caesar’s _praefecti equitum_ seem to have been tribal chiefs; one may cite, for example, the Aeduan Dumnorix,[39] the heroic veteran Vertiscus,[40] and the two treacherous Allobroges, Roucillus and Egus, the sons of Adbucillus.[41] On the other hand, when we meet with an ala Scaevae on an early inscription, it is difficult to avoid agreeing with Mommsen that it was called after Caesar’s well-known officer of that name.[42] Many other cavalry regiments, which are shown by epigraphical evidence to have existed at an early date and to have been Gallic in composition, bear titles similarly formed from personal names.[43] It is suggested that these corps, or at any rate the majority of them, represent tribal contingents embodied by Caesar at the time of the Civil Wars under the title of _alae_ and placed under his veteran officers. Thus during this period the use of the term _ala_ in the restricted sense would be already known, although only the older and wider use appears in literature. How slowly the new expression won favour is shown by the fact that during the reigns of Augustus and Tiberius the officers commanding these regiments were usually described on inscriptions simply as _praefectus equitum_, and it was not until after this that the title _praefectus alae_ came to be generally adopted.[44] Curiously enough, we find very few cohorts with titles which suggest a similar history.[45] Probably in this case Augustus’s reorganization was more thorough and the existing regiments had not, like some of Caesar’s corps of Gallic cavalry, a record of individual achievement which might exempt them from its scope.