mines. Exceptionally, a gubernatorial position was styled "comes". For example, the comes Orientis, actually one of the vicarii, was an official who controlled the large and strategically important Imperial Diocese of the East by supervising the governors of this collection of provinces, but he was in turn supervised by the praefectus praetorio Orientis. Further, the principal officials of some less important governmental departments who were under the authority of otherwise styled, high ranking, territorial officials could be titled "comes", e. g. under the praefectus urbi of Rome, himself a vir illustris, was a comes formarum, comes riparum et alvei Tiberis et Cloacarum ("Count of the Coast of the Tiber and the Canalisation"), and comes Portus ("Count of the Port"). The title "comes consistorianus" or "comes consistorialis" indicated specially appointed members to the consistorium, the council of the Roman emperor's closest advisors. comes rei militaris The comes rei militaris held martial appointments, and were commanders of . They ranked superior to a dux but inferior to the magister peditum and magister equitum; they were the superiors of a series of military stations, each commanded by a praepositus limitis ("border commander") and/or unit commanders, e. g., tribunes of cohorts, alae (auxiliary equivalents), numeri, and in the Eastern Empire even legions. The Notitia Dignitatum of the early AD 5th century enumerates 6 such offices, being of the dignity of vir spectabilis, in the Western Empire: comes Italiae, comes Africae, comes Tingitaniae, comes Tractus Argentoratensis, and comes Britanniarum ad Litoris Saxonici per Britanniam; and 2 in the Eastern Empire: comes (limitis) Aegypti and comes Isauriae. comes Africae: Official responsible for the defense of Roman Africa. comes tractus Argentoratensis: Official responsible for the defense of part of Gallia. comes Avernorum: Official responsible for the defense of the other part of Gallia. comes Britanniarum: Official responsible for the defense of Britannia. This office presumably expired circa AD 410 when the last Roman troops left that province. comes Litoris Saxonici per Britanniam: Official responsible for the defense of the Saxon shore of Britannia. comes Hispaniarum: Official responsible for the defense of Hispania. As the number of comites increased, that dignity was devalued. This caused the introduction of classes of comites, denominated and ranked the first, second, and third "ordines". comites dominorum nostrorum The comites dominorum nostrorum (plural of Comes D. N.), (literally "Companions of Our Lords [Emperors]") were a mounted Imperial bodyguard during the tetrarchy of Emperor