SERIOUS ACCIDENT IN THE HUNTING FIELD. -- On Wednesday, whilst Captain COOKE, of the 17th Royal Lancers, stationed at Aldershot, was hunting with the Cheshire hounds between Crewe and Nantwich, the mare which he rode bolted, pitching her rider over her head for a considerable distance, landing him in a bog.  Assistance was at once rendered, and it was found that he was much injured.  He was at once attended by Drs. ATKINSON and ATTHILL, who found that his shoulder had been dislocated, besides having sustained other injuries.  His arm having been set, Captain COOKE was conveyed to the Crewe Arms Hotel, and after a little rest he was placed in a carriage and removed to Chester, where he is temporarily residing.