Pangborn, Jack (University of California, Davis), and Mortimer P. Starr. Ultrastructure of Lampropedia hyalina. J. Bacteriol. 91:2025-2030. 1966.-In an effort to learn more about the structural bases for the sheeting format of Lampropedia hyalina, ultrathin sections were cut which were precisely oriented either parallel to or perpendicular to the plane of growth; these were examined by electron microscopy. Lampropedia cells show cytological features typical of gram-negative bacteria. In addition, three uniquely structured layers are found exterior to the cell walls. Details are presented regarding the fine structures and geometric relationships of these layers; their probable origins and involvements in the characteristic cellular juxtaposition are discussed.