Original description of Aporrhais (Platyoptera) extenta by Conrad, 1855, p. 260:
- "Shell independent of labrum fusiform, with prominent revolving rounded lines and intermediate fine lines, from one to three, and longitudinal microscopic lines; volutions rounded, covered towards the apex with a polished calcareous deposit; labrum within with impressed radiating lines, becoming well marked furrows towards the base."
Locus typicus: Jackson, Mississippi, USA.
Stratum typicum: Moody's Branch Formation, Jackson Group, upper Eocene
Aporrhais (Platyoptera) extenta Conrad in Wailes, 1854, pl. XVI, fig. 3
Platyoptera extenta (Conrad in Wailes, 1854); Eocene; Town Creek, Jackson, Mississippi, USA; Coll. BM(NH) no. GG12761; Copyright BM(NH)
- T.A. Conrad - Observations on the Eocene deposit of Jackson, Mississippi, with the descriptions of thirty-four new species of shells and corals (Proceedings of the Academy of Natural Sciences of Philadelphia Vol. VII 1854, 1855), Fulltext