Murder.-op Saturday last, Thomas Grif- fin Thornton. Sheriff of Caroline county. Va. was murdered. It seems he was despatched by two gun-shot wounds; one in the abdo- men. and the other in the back. His horse appears to have been led about fifty yards from the scene of the murder and shot. On Sunday afternoon, a man was arrested in this town on suspicion of having participated in this most dreadful ransaction.-ArenG.