Family NERINELLIDAE Pchelintsev, 1960 (Fig. 4 A-H)

Nerinellidae Pchelintsev in Pchelintsev & Korobkov, 1960: 124.

TYPE GENUS. — Nerinella Sharpe, 1850 (1850: 107).

TYPE SPECIES. — N. dupiniana d’Orbigny, 1842 (1842: 81).

FAMILY CHARACTERS. — Shells of medium size, narrow turriculate. Whorls high, moderately convex to deeply concave, with sculpture of spiral ribs or nodes. Aperture with basal siphonal notch. Columella solid, with small plait abapically. One parietal and one palatal plait. Parietal plait merging with external margin of the inductura.

REMARKS

Nerineoidea with relatively small and narrow shells and high whorls have generally been assigned to the Nerinellidae. According to Cossmann (1898), Nerinella differs from Eunerinea Cox, 1949 by its suture, which is positioned above the sutural bulge, whereas it is located on top of the bulge or between bulges in the Eunerineidae n. fam. This distinction is unsatisfactory (see Fig.4D). Even in the type species, Nerinella dupiniana (d’Orbigny, 1842), two weak bulges are visible (Kollmann 2005). Sharpe (1850) distinguishes Nerinella by its high, narrow whorls from Eunerinea. Although this morphological character is common to most members of Nerinella, it is not specific by itself.Most significant is the siphonal notch, a narrow sinus of the basal lip near the abapical end of the columella, which served in protruding the inhalant siphon. In contrast, the aperture of the Eunerineidae n. fam. extends into a twisted siphonal canal.

The Early Jurassic Nerinella grossouvrei Cossmann,1896 is the earliest representative of this genus. It differs from typical Nerinellidae taxa by the obscurely angular periphery of the last whorl (Fig. 4 A-C). The whorls are slightly concave to slightly convex. A columellar, a parietal and a palatal plait is present (Fig. 4B).