Dictionary of Greek and Roman Geography/Iatrus
IATRUS (in the Peut. Tab. Iantrus), a river traversing the central part of Moesia. It has its sources in Mount Haemus, and, having in its course to the north received the waters of several tributaries, falls into the Danube close by the town of Iatra. (Plin. iii. 29, where the common reading is Ieterus; Jornand. Get. 18; Geogr. Rav. iv. 7.) It is probably the same as the Athrys (Ἄθρυς) mentioned by Herodotus (iv. 49). Its modern name is Iantra. [ L. S. ]