FROM GALLIPOLIS.Gallipolis, 0., Sept. 7.—Rebel cavalry overfive hundred strong made their appearance at six o’clock this morning on the Ohio river opposite Swan creek eighteen miles below Gallipolis.They were going in the direction of Guvan-dotte and are supposed to be a portion of Jenkins’s command.Lieutenant Hoy of the Sixth Virginia regiment, who was taken prisoner at Weston, reached here this evening, having yesterday been paroled by Jenkins.He was with them during their march from Weston to the Kanawha river.He estimates the force at 1,500.Measures have been taken to-day which will no doubt prove successful in opening up communication with the Kanawha region.