Fig. 15 in Scaphites Of The ''Nodosus Group'' From The Upper Cretaceous (Campanian) Of The Western Interior Of North America

Fig. 15. Embryonic whorls of Hoploscaphites nodosus (Owen, 1852) and H. brevis (Meek, 1876), AMNH loc. 3274, Baculites compressus–B. cuneatus zones, Pierre Shale, Meade County, South Dakota. A– C. Hoploscaphites brevis (Meek, 1876), AMNH 58539. A. The embryonic shell is covered with tubercles. B. Most of the tubercles are irregularly distributed but some are aligned in longitudinal rows. C. The tubercles vary in diameter and range from 5–10 Mm. D–F. Hoploscaphites nodosus (Owen, 1852), AMNH 66259. D. Ventral surface of the embryonic shell just adapical of the primary constriction. The surface is covered with a thin dorsal layer and retains the outline of the dorsal sutures of the succeeding whorl. E. Muscle scar in the dorsal lobe. F. The muscle scar is demarcated by a fine-grained texture.