Protanisoceras (Protanisoceras) aff. coptense  Casey, 1961

Measurements	L	D	H/D	T/D	O/D	H/T
CP-645	24.6	48.5	0.33	0.35	0.47	0.96

Age	Origin
Grey clay, subhilli zone Lower Albian	Mesnil-Saint-Père Aube, France

Description. A pyritic fragment, septate and coiled in a plane, with a barely depressed section, resembling a semicircle capped by a half-hexagon. 17 radial ribs without lateral tubercles, tapering dorsally, with wider and somewhat irregular interspaces. Five are stronger and bear two ventrolateral tubercles. They are broadened and sagged between these tubercles and form a weak proverse sinus on dorsum. The other ribs have weak tubercles, reduced to angulations on ventrolateral shoulders. There are three thin ribs between two strong ones, except between the last two strong ribs where there are only two. The rib index is 4. The sutures reveal a fairly broad and bifid ventral lobe, a deep and narrow, nearly symmetrical and bifid first lateral lobe, and a small bifid dorsal lobe.

Remarks. Personal discovery. The three most similar species, which may also have three thin ribs between two tuberculate ones, are P. (P.) raulinianum var. communis Spath, 1939, P. (P.) lardyi (Pictet & Renevier, 1854), and P. (P.) vaucherianum (Pictet, 1847). However, they have a trifid dorsal lobe. Furthermore, the first two exhibit lateral tubercles, while the second does not, but has irregularly distributed thin ribs, from 0 to 3, between two strong tuberculate ribs. We classify our specimen as species affinis (aff.) because the species is known from a single specimen from the main mammillatum bed of Folkestone, it has not been reported in France, and the holotype has a slightly compressed section.