Exelissa, Piette, 1860

Exelissa View in CoL ? sp.

( Figs 64–65 View Figs 60–66 )

Material – A single specimen, combination of imprint and cross section of whorls on a broken rock surface.

Measurements – Inv. No.: BHU 2020I 303; H dam. = 4.2 mm.

Description – The remnants indicate a pupiform/bottle shaped, moderately turriculate shell. Its earliest preserved part shows a single whorl with rounded surface, perhaps it is (part of) the protoconch then two whorls of pagodiform outline with a keel on their angulation follow. From the third preserved whorl, a second keel also appears subsuturally; subsequently the whorls remain convex but lose their pagodiform nature. The bicarinate whorl surface lasts to the latest preserved whorl (? last whorl); two new spiral threads also develop on this shell part, one between the primary carinae and another one just above the suture. Together with the second carina, straight, prosocline ribs also appear and extend from suture to suture. Estimated number of these ribs is six (±1) per whorl. The ribs are aligned to each other on the neighbouring whorls; their rows are prosocline on the early teleoconch and form apparently twisted ridges around the axis then become more or less orthocline. Remains of the base show several spiral threads as ornament. No growth lines are observable.

Remarks – The genus name Exelissa ? seems to approach the right systematic place of this species. However, the rather low spire with pupiform shell outline and “twisted” shell parts in early growth stage occurs also in Cryptaulax or in Xystrella . Well preserved material with protoconch and peristome is needed to find the correct generic position.

Occurrence – Ler, Chari Formation, Callovian.