MY´SIUS(Μύσιος), a tributary of the Caicus, on the frontiers of Mysia, having its sources on Mount Temnus, and joining the Caicus in the neighbourhood of Pergamum. (Strab. 13. p. 616.) According to Ovid (Ov. Met. 15.277) Mysius was only another name for Caicus, whence some have inferred that the upper part of the Caicus was actually called Mysius. It is generally believed that the Mysius is the same as the modern Bergma. [L. S.]