The corrosion resin-casts and the tissue preparations of the digestive diverticula of the pen shell, Atriana (Servatriana) lischkeana were observed. The resin-casts were made of the prepolymerization methyl methacrylate (Mercox CL-2R) containing 10% Mercox MA. The tissue preparations were stained with Azan. The digestive diverticula divided into three groups and located at the right and the left sides of the stomach, and at the esophageal orifice. The tubules were clearly observed with a stereoscope after the membrane covering the digestive diverticula was removed. The stomach had three main ducts of the digestive diverticula. These ducts had the openings (the orifices) in the inner wall of the stomach. The iiner walls of the main and the secondary ducts had a similar tissue structure which were made up of the uniform fragellated cells covered with the cilia. The tubules of digestive diverticula branched out the smaller tubules after separating from the secondary ducts.