Serous Membrane
in anatomy, a membrane having its surface moistened by serum. They line the cavities of the body from which there is no outlet. The chief are the peritoneum, the two pleuræ, the pericardium, and the arachnoid membrane. Serous membranes differ from mucous membranes in having thinner layers, finer fiber, and an epithelium with only a single layer of polygonal cells.
SERPENT