Tonicia schrammi (Shuttleworth, 1856). Scanning electron images of a specimen from Cabaña CONANP (CNMO4992, 27.5 mm length). A dorsal view of head valve (I), SB = 1 mm B dorsal view of tail valve (VIII), SB = 1 mm C dorsal view of intermediate valve IV, SB = 2 mm D detail of lateral area in dorsal view of the intermediate valve IV, SB = 1 mm E lateral area ocelli detail of intermediate valve IV, SB = 100 μm F head valve (I) detail, showing the ocelli alignment, SB = 50 μm. G, ventral view of intermediate valve IV, SB = 1 mm H insertion teeth and slit detail of intermediate valve IV in ventral view, SB = 50 μm I radular teeth, SB = 100 μm J central and minor lateral teeth detail, SB = 10 μm K major lateral teeth detail, SB = 50 μm.