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1 The alimentary canal is a muscular tube about 9 maters long. (What size) 2 The wall of the alimentary canal consists of four disfinct layers. (How many) 3 Mucous membrane is formed of surface epithelium and a small amount of smooth muscle. (What ... of) 4 The mucosa protects the tissues beneath. (What) 5 The fibers of the outer muscular coat run lengthwise. (How) 6 The cells of the serosa secrete serous fluid. (What)