| Measurements | D mm | H/D | T/D | O/D | H/T |
|---|---|---|---|---|---|
| Holotype | 57 | 0.43 | 0.44 | 0.29 | 0.98 |
| CP-632 | 67.9 (58.9) | 0.42 | 0.39 | 0.30 | 1.07 |
| Spath pl.30 fig.5 | 82 | 0.39 | 0.34 | 0.32 | 1.15 |
| Age | Origin |
|---|---|
|
Phosphatic level P5 cristatum zone Base of Upper Albian |
Wissant Pas-de-Calais France |
Description. Black phosphate ammonite with test remains in the form of a pinkish film. Moderately evolute shell with slightly compressed whorls, 40% covered. The body chamber occupies the last third of the spire, and one of its flanks is missing. Low umbilical wall, sloping at 45°, broadly rounded towards the flank. Nine very prominent umbilical tubercles, radially pinched, inclined forward, moving to the lower third of whorl height at the end of the spire. Twice as many ventrolateral tubercles, low and long, subparallel to the siphon, with a broad, blunt crest, forming extra thicknesses at the top of the flank if one follows one of the ventral shoulders. Indistinct costulation, but in raking light, zigzag ribs can be discerned. The cross-section is distinctly concave at the umbilical tubercles.
Remarks. See the description of Spath p. 290 and the examples shown pl. 27, fig. 2, pl. 29, fig. 1c and pl. 30, fig. 1a-b and 5. Our specimen is very similar to the one photographed in profile on pl. 30, fig. 5. The other, smaller Spath specimens have discernible but weak ribs.