Naticopsis sp. 2

(Fig. 20 D–F)

Material. One specimen: ESKU-19- LP 46.

Dimensions (mm): ESKU-19- LP 46: height = 9.3; width = 10.3; apical angle = 112 º; apertural height = 7.5; apertural width = 7.7.

Description. Moderately low-spired shell, naticiform, consisting of three rapidly expanding whorls; whorls smooth, strongly convex, rounded, embracing at periphery; spire low but distinctly elevated; body-whorl inflated, very large and much higher than spire with height about 90% of total height; periphery at about mid-whorl; base convex; suture shallow but impressed; anomphalous; aperture evenly rounded in cross section, lip thin, inner lip arched.

Remarks. Naticopsis sp. 2 differs from Naticopsis sp. 1 in having more flattened upper whorl surface, lacking callus, having a higher whorl expansion rate and a rounded aperture. It resembles Naticopsis subovata Worthen in Meek & Worthen (1873) as illustrated by Knight (1933 b, p. 379, pl. 43, fig. 2a–j) in size, shell shape and pleural angle. N. wortheni Knight, 1933 b (p. 377, pl. 43, fig. 3a–k) is also similar. Knight (1933 b) mentioned that these two species, N. subovata and N. wortheni, are very close to each other but N. subovata can be differentiated from N. wortheni in having a swelling just above the mid-whorl height, and by the shape of the columellar lip, which is evenly crescent-shaped in N. subovata while it is slightly angled in N. wortheni . Although the parietal area of the present specimen is obscure it seems closer to N. subovata . The present specimen is also similar to the specimens illustrated and described as N. praealta Wanner, 1922 by Batten (1979; p. 14, fig. 16a–b) from the Permian of Perak, Malaysia but the latter specimens are more slender and relatively high-spired.