Scanning electron micrographs of Nebela aliciae. (A, B) Broad lateral views of two specimens to illustrate general shape. (C) Narrow lateral view to show lateral keel. (D) Close up view of lateral keel showing its structure. (E, F) Broad lateral view of apertural region to illustrate aperture outline and collar of organic cement. (G, H) Close up view of lateral keel. (I) Detail of shell surface showing shape and arrangement of shell-plates.