Light (A) and scanning electron (B-I) micrographs of Corythion constricta. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Apertural view of two individuals showing general shape and haphazardly arranged shell-plates. (E) Dorsal view. (F) Lateral view showing shell compression and oblique aperture. (G) Close up view of aperture to show its oval shape and surrounding apertural-plates, each of them with median dorsal tooth. (H) Dorsal view of apertural region showing pronounced pre-apertural rim, consisting by two or three rows elongated-oval plates. (I) Detail of shell surface to show arrangement of shell-plates.