Figure 16 in Phylogeny of the deep-sea cirripede family Scalpellidae (Crustacea, Thoracica) based on shell capitular plate morphology

Figure 16. Eocene Scalpellinae, to illustrate the evolutionary origin of the genus Scalpellum. Scuta, terga, and carinae. A–F, Scalpellum fischeri Bertrand, 1891, Lutetian, Calcaire Grossier, Chaussy, near Mantes (Seine-et-Oise), Paris Basin, France. A, B, scutum, external and internal views (original of Withers, 1953, pl. 38, figs 3, 4), NHMUK In. 39466. C, tergum, external view (original of Withers, 1953, pl. 38, figs 5, 6), NHMUK In. 39468. D–F, carina (original of Withers, 1953, pl. 38, fig. 1), NHMUK In. 39465. L, Arcoscalpellum venablesi Withers, 1953, lower Ypresian, Division B1 of London Clay ('Fish Tooth Bed'), Bognor Regis, Sussex, UK. G, H, scutum, in external and internal views (original of Withers, 1953, pl. 63, fig. 1), NHMUK In. 39072. I, tergum (original of Withers, 1953, pl. 63, fig. 4), NHMUK In. 39072. J–L, carina (original of Withers, 1953, pl. 63, fig. 1), NHMUK In. 39033. M–R, Arcoscalpellum quadratum (Dixon, 1850), lower Ypresian, Division A3 of London Clay ('Bognor Rock'), Bognor Regis, Sussex, UK. M, N, scutum. O, tergum. P–R, carina. NHMUK In. 32543–32550. Note the progressive elongation of the apical part of the scutum, the change in shape of the tergum, and the subapical migration of the carinal umbo. Compare with extant Scalpellum in Figure 15. Scale bars: 5 mm.