Ungulinidae Gray 1854

Figures 1–6.Diplodonta portesiana. Holotype (NHMUK 1854.12.4.770; L: 20 mm; H: 17 mm). 1 Left valve, external view 2 Right valve, external view 3 Left valve, internal view 4 Right valve, internal view 5 Left hinge detail 6 Right hinge detail. Scale: 2 mm.

Figures 7–14.Specimen of Diplodonta portesiana (MZSP 22747, L: 13.4 mm, H: 13.1 mm, width: 7.7 mm). 7 Left valve, external view 8 Right valve, external view 9 Left valve, internal view 10 Right valve, internal view 11 Dorsal view 12 Left hinge detail 13 Right hinge detail 14 External surface of shell under SEM; Scale: 2 mm, except 14: 200 µm.

Figures 15–22.Anatomy of Diplodonta portesiana. 15 Right view, right mantle lobe removed 16 Same view, gill removed 17 Mantle border, transverse section in median portion 18 Gill, transverse section in middle portion 19 Incurrent and excurrent openings, posterior view 20 Same, anterior-slightly right view 21 Pericardium region, dorsal view 22 Labial palps, ventral view, hemipalps deflected; Scale: 2 mm, except 17, 18: 1mm.

Figures 23–29.Anatomy of Diplodonta portesiana. 23 Digestive system as in situ, right view, foot and main muscles also shown 24 Stomach, left view 25 Internal stomach surface, right view, dorsal gastric wall sectioned longitudinally and deflected 26 Nervous system and topology of other main structures, right view 27 Visceral ganglia, ventral view 28 Pedal ganglia, superior figure in right view, inferior figure in ventral view 29 Cerebral ganglia, anterior view; Scale: 23, 26: 2 mm; 24, 25: 1 mm; 27–29: 0,5 mm.