Sellaea stryx (Di Stefano, 1889 )

Sellaea stryx (Di Stefano, 1889)

( Fig. 8 View FIG A-F)

Caprotina stryx Di Stefano, 1889 : XI, 23, 24, 40, pl. 7, fig. 1a-f. — Parona 1899: 381. — Parona et al. 1909: 186, pl. XXII, figs 2-3. — Kutassy 1934: 140, 141.

Caprotina View in CoL cfr. strix – Parona 1897: 14.

Sellaea stryx – Rineau & Masse 2022: 2, 5, 9, 12, 13.

MATERIAL EXAMINED. — Sellaea is found in dense accumulation of both connected and isolated shells in Mazo Chico (Soba Valley) ( Fig. 8G View FIG ). Only outcrop photographs of natural sections have been studied due to the hardness of the limestone beds that prevent sampling specimens.

STUDY INTERVAL. — Mazo Chico limestones, Ramales Formation (upper middle Albian).

DESCRIPTION

Shell inequivalve; left valve conical and coiled (less than one whorl), right valve conical and straight, triangular in longitudinal section ( Fig. 8A, B View FIG ; mean height from umbo to commissure approximately 130 mm). Valves ovoid in transversal section (mean section 80 × 60 mm) with a ventral part straight to slightly depressed. Some right valves deformed in transversal section due to growing encrusted to other Sellaea individuals in bouquets ( Fig. 8C View FIG ). Outer calcitic shell layer very thin (mean thickness 0.5mm), generally not preserved. Inner aragonitic shell layer thick (mean thickness in ventral part 4 mm). Ligament invaginated in a reniform posterodorsal ligamentary cavity.