Pentamerus lævis, Sow. Caradoc Sandstone. Perhaps the young of Pentamerus oblongus.
- a, b. Views of the shell itself, from figures in Murchison's Sil. Syst.
- c. Cast with portion of shell remaining, and with the hollow of the central septum filled with spar.
- d. Internal cast of a valve, the space once occupied by the septum being represented by a hollow in which is seen a cast of the chamber within the septum.
Fig. 427.
Cast of Orthis grandis, J. Sow. Horderley; two-thirds of nat. size.
Fig. 428.
