Ceratolithina hamata Martini, 1967
A laminated, rod‑like crystalline block may bear an anterior‑lateral blade and, in some forms, a posterior-lateral blade, with all components functioning as a single optical unit.
This single‑crystalline block exhibits symmetrical extinction (extinct at 45°), and the orientation of the optic axis (c‑axis) cannot be resolved as either length‑slow (+) or length‑fast (–).
The width of the laminas tapers gently perpendicular to the natural settling position; however, only a minority of these multilaminar structures expand sufficiently to form lateral blades.
Martini, E. 1967. Ceratolithina hamata n. g., n. sp., aus dem Alb von N-Deutschland (Nannoplankton, incertae sedis). Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 128: 294-298.