Light (A) and scanning electron (B-I) micrographs of Trinema lineare. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) Apertural, dorsal and lateral views in one place. (D-E) Apertural view of two individuals to illustrate general shape and regular arrangement of shell-plates. (F) Dorsal view. (G) Lateral view. (H) Close up view of aperture to illustrate its shape, arrangement of denticulate apertural-plates and two rows of small shell-plates. (I) Detail of shell surface to show large, circular shell-plates and small, oval shell-plates which haphazardly fill the interstices between large plates.