One which relates to business done or transacted upon the sea and in sea ports, and over which the courts of admiralty have jurisdiction concurrent with the courts of common law; such contracts include according to civilians and jurists among other things, charter parties, affreightments, marine hypothecations, contracts for the marine service in the building, re-pairing, supplying and navigating ships; contracts and quasi contracts respecting averages, contributions and jettisons, and policies of insurance. 2 Gall. R. 398, where Judge Story gave a very learned opinion on the subject.