A strain of Lampropedia hyalina (A.T.C.C. 11041) has lost the ability to form the tablets of cells and sheets. In fact, it has lost the characters that give it generic status and allow its identification. Detailed comparison with a sheeting strain of the species indicates that what is lost is an intercalated layer, which glues together the cells of the tablet, and the outermost of the two structured layers which form the surface envelope. Both of these elisions may be important to tablet formation but the former is probably the most important. There is evidence that these layers may still be retained on occasional cells as small islands of material in the appropriate anatomical regions. However, although these islands must reproduce and be perpetuated in the strain, there is no evidence that the layers can be fully recovered and no fully characteristic Lampropedia have been isolated from the mutilated strain.