196 THE HISTORY -BopkL, demonftrate the number of both to have been fifty or fixty at leaft ,5 . And the fuggeftions of common fenfe, ftill more au- thentic .than records, evince the abfolute neceffity of as many (independently of the national auxiliaries) to fecure the wide- ^ extended dominions of the Roman empire. The exprefs num- ber of the Roman legions appears indeed from Dio to have been only about twenty -three or twenty-five from the reign of Avguftus to the reign of Alexander Severus ,6 , and appears, from inscriptions to have never exceeded thirty-fix afterwards. And this has been generally fuppofed by our antiquarians to be abfb- lutely the whole number of the Roman legions. But as feveral of thefe were certainly legions of foreign volunteers, fb each of the others, except perhaps the eighth the eleventh the four- teenth and the thirtieth, had feveral extraordinary brigades of citizens or of foreigners belonging to them, every one of which fiad equally, the complement and the denomination of a legiph, 1 and .was . diftinguifhed from each other and from the original brigade of the legion by fome additional title. This title was gfjOeraUy aflumed by thefe . and by the original brigades frdm th$ kingdbpi? of their firft or longeft refidence. Hence in Dio's catalogue of purely TRonian legions we find fo many of them diftinguifhed by the denominations of Gallic, Cyrenean, Scythi- an, Macedonian, Egyptian, Germanic, and Parthic ,7 . And hence the tenth Twin legion, being long ftationed in Germany, and the fecond Auguftan, being longer fettled in Britain, ap- pear under the, particular appellation of the tenth Germanic and the feebnd Britanic legions in Ptolemy and the Notitia. The titles of the original and of the additional brigades were frequently derived from the name of the ,emperor under whom the legion or its brigades had been originally raifed, or by whom the one or the other had been particularly favoured. And .as the original and the additional battalions can feldom be di- ftinguifhed by the nature of their names, fo may they conftant- Jy be diftinguifhed by the catalogue of Dio. Thus the fevehth "legion had. the' feveral legionary brigades which were called the Teveqth Claudian and the feventh Galban, two brigades confifting i