(Ehrenberg)
Small subspherical cephalis with apical horn. Thorax small, inflated, thick-walled. Abdomen and 4-5 post-abdominal segments thin-walled, with pores arranged in longitudinal rows. Shell height: 120-200 µm.
Eucyrtidium hexagonatum Haeckel is closely related to this species; according to Nigrini (1967) it can be distinguished from Eucyrtidium acuminatum by the sharp change in contour at the lumbar stricture.
Ref.: Nigrini and Moore (1979).