ATTEMPTED ARREST OF FUGITIVE SLAVES. - The Sandusky Register says, that the city was thrown into intense excitement on Monday evening, by an attempt to arrest several negroes at the moment of their departure for Detroit. There were two men, two women, and several children on board the steamer Arrow, supposed to be escaped slaves. Just as the boat was leaving her landing, a man claiming to be the owner of one of the women and her children, went on board, and aided by the City Marshal, forcibly dragged the woman and her children on shore. They were then taken to the Mayor’s office, which was immediately filed by an excited crowd, among whom were numbers of blacks and whites, who were armed with clubs. After a delay of half an hour or more, no one appeared to claim the fugitives, and no authority for their arrest being exhibited, the Negroes were allowed to depart in peace.