ST. HELENA.-We learn from our vessels of war, stationed on the western coast of Africa, that from the 1st of April, 1844, to 6th July, 1845, no fewer than 75 slavers have been captured by them, the Americans having, during the same period, captured 1 slaver. making a total of 76 captured vessels during a period of fifteen months and six days -St. Helena Government Gazette, September 13,