| Measurements | D mm | H/D | T/D | O/D | H/T |
|---|---|---|---|---|---|
| RJ-193 | 42.8 | 0.51 | 0.32 | 0.20 | 1.61 |
| Holotype | 49 | 0.47 | 0.27 | 0.23 | 1.74 |
| CP-402 | 56.8 | 0.42 | 0.34 | 0.18 | 1.24 |
| CP-373 | 74.8 | 0.50 | 0.32 | 0.16 | 1.55 |
| Age | Origin |
|---|---|
|
Grey clay H. (I.) steinmanni zone Lower Albian |
Bully, Pays de Bray Seine Maritime Normandy, France |
Description. A phosphatic fully septate specimen with a pearly test except on the last half-whorl. Whorls 70% covered, with parallel and flat flanks up to one-third of their height, then slightly convex and converging towards an arched venter. Umbilicus with an abrupt wall and angular edge. The test bears eight thin, falcate ribs, bordered forward by a narrow, shallow constriction. The first ones originate near the umbilicus while the others are limited to the outer half of the flanks. Ribs and constrictions cross venter with a forward rounded sinus. Under magnification, other, weaker ribs are visible here and there, limited to upper flanks and venter. On the testless body chamber, under tangent light, five other constrictions are bearly visible. The sutures, which are well exposed, are not very indented. Our CP-402 and CP-373 from Mangystau are thicker, which reduces the H/T ratio. They have 10 weak constrictions that notch the umbilical wall and follow a thin ridge, limited to the venter and its shoulders.
Remarks. This species is unknown in the Aube region. According to Breistroffer (1947, p. 63), it differs from B. dupinianum (see its entry) by its less open umbilicus, its more discoid shape, its thinner whorls, its less pronounced ornamentation, and the details of its septa. Casey (1961) examined the holotype from Machéroménil (Ardennes) and did not observe a narrower umbilicus. He ultimately noted only more compressed whorls and a weaker sculpture, tending to disappear in the inner half of the flanks. Casey's specimens have 7-8 constrictions per whorl. On the last whorl, ours has 8 on the phragmocone with a test, and 5 on the body chamber without test, therefore more than 10 as in B. albense (see its entry). Since the sutures of the three species illustrated by Jaffré (2007) are also very similar, it is possible that Beudanticeras albense and arduennes are simply less robust variants of B. dupinianum, which predates them.