Turbinolia Lamarck, 1816

Genus Turbinolia Lamarck, 1816 View in CoL

Type species. Turbinolia sulcata Lamarck, 1816 , Middle Eocene of France (by subsequent designation Milne Edwards & Haime, 1850).

Diagnosis. Solitary, ceratoid, circular in cross section and small (rarely exceeding 3.5 mm) in diameter; septa compact, exsert, hexamerally arranged in 2–4 cycles (12–48 septa); costae independent in origin, usually well-developed, smooth ridges, and C1–2 sometimes ‘thickened basally’. Costae present or absent, depending on species; in type species present as alignment of low mounds, becoming low ridges only near calice; series of circular pits up to 70 μm in diameter flank each costa, each bordered on distal and proximal edges by small thecal buttresses oriented perpendicular to the costa and often fused to the costae, if present; thecal pits thus appear to form a double column, often in alternating arrangement. Paliform structures absent. Columella quite variable, including styliform, stellate, and lamellar.