HE´RIUS(Ἥριος). Ptolemy (Ptol. 2.8.1) places the Herius on the coast of Gallia Lugdunensis, between the Brivates Portus and the Vindana or Vidana Portus. Ptolemy's latitude of the mouth of the Herius (49 1/4°) makes it nearly as far north as the outlet of the Seine. D'Anville [DURETIE] supposes the Herius to be the Vilaine, the first large river north of the Loire. He adds ( Notice, &c., Herius Fluv.) that the passage of the Vilainebetween Roche-Bernardand the mouth of the river is now called Treig-hier, and that we may readily believe Treig-hierto be a corruption of Trajectum Herii. This may be so; or Treig-hiermay be the old Celtic name. Some geographers assume the Herius to be the small river Auraynorth of the Vilaine;but this is only a guess like the other. [G.L]>