Marshallora adversa

Marshallora cf. adversa (Montagu, 1803) (Fig. 5J 1-J 3) cf. Murex adversus Montagu, 1803: 271. cf. Triforis perversa var. adversa – Harmer 1918: 425, pl. 41 fig. 25. cf. Mashallora cf. adversa – Van Dingenen et al. 2016: 162, pl. 14 figs 7, 8. MATERIAL AND DIMENSIONS. — Maximum height 5.8 mm (incomplete), width 3.2 mm.— RGM.1364975 (3), leg. ACJ; RGM.1365280 (1), leg. AWJ. SPECIES CHARACTERISATION. — Apex lacking on all material. Overall shell is slightly spindle shaped. Adult whorls separated by superficial suture; sculpture of three spiral ribs, middle rib slightly stronger than other ribs; numerous weak, prosocline ribs, with rounded tubercles developed at intersections; on last whorl the fourth basal rib is smooth to slightly knobbed and a fifth rib in one specimen is smooth reminiscent of a recent Canarian Island morph of this species (H. Bakker, pers. comm.). The Selsoif specimens are large for this species. DISTRIBUTION. — Lower Pleistocene: Atlantic, Selsoif, NW France (this paper). Today Marshallora adversa is distributed in the NE Atlantic from Scandinavia to the Canaries and in the entire Mediterranean (Bouchet 1985). REMARKS The three extant West European species Marshallora adversa (Montagu, 1803), Cheirodonta pallescens (Jeffreys, 1867) and Similiphora similior (Bouchet & Guillemot, 1978) are almost indistinguishable on shell characters alone (Marquet 1996). The protoconch and position of appearance of the cords on early whorls is required to make a definitive attribution.