Diagnoza

Conch probably subglobose; relatively small and very narrow or closed umbilicus; transverse striae, broadly convex towards the front, very fine, bifurcating several times; rib direction essentially radial, non-crenulate on shell surfaces; umbilical margin in the adult is very frequently raised into a rounded rim across which the ribs pass without weakening.

Porównanie

Differs from C. nititoides and all Cravenoceratoides by its weak, rather coarse spiral ornament; N. nuculum lacks the raised umbilical rim at the shell surface, though a rim is sometimes apparent on the solid internal cast.

Autekologia

Występowanie geograficzne

Great Britain (Staffordshire, Yorkshire), Belgium (Namur), Germany (Rhenish Slate Mts.) and Poland (Lublin Coal Basin).

Zasięg czasowy

Carboniferous; C. nititoides – N .nuculum zones

Materiały muzealne

One specimen figured in Korejwo, 1986.

Literatura

Bisat, W.S. 1932. On some lower Sabdenian goniatites. Transactions of the Leeds Geological Association 5: 27-36.

Korejwo, K. 1986. Biostratigraphy of the Carboniferous deposits of the Świdnik blocks (Lublin Coal Basin). Acta Geologica Polonica 36 (4): 337-346.