Eumorphoceras bisulcatum (Girty, 1909) z wiercenia MIrne IG 1, ontogenetyczne przemiany pokroju muszli.

Diagnoza

Discoidal shell, becoming increasingly so with advancing age; umbilicus moderately large, proportionately smaller in mature specimens than in young ones; cross section changes in ontogeny, from transverse and elliptical to radially elongate and elliptical at maturity; surface is divided by two revolving sulci into three nearly equal portions;  areas nearest the umbilicus are marked by regular, strong, angular, radiating ribs, separated by subangular channels of about the same width; near the revolving sulci the ribs and channels are bent strongly forward, and at the same time they rapidly die out and disappear; ventral area rises rather strongly from the two sulci, by which it is defined.

Porównanie

Autekologia

Występowanie geograficzne

Zasięg czasowy

Materiały muzealne

Literatura

Żelichowski 1972

Musiał & Tabor 1988

Bojkowski 1979