Fig. 413.
Terebratula Wilsoni, Sow. Aymestry.
Fig. 414.
Atrypa reticularis. Linn. Syn. Terebratula affinis, Min. Con. Aymestry.
- a. upper valve.
- b. lower.
- c. anterior margin of the valves.
4. Lower Ludlow shale.—A dark grey argillaceous deposit, containing, among other fossils, the new genera of chambered shells, the Phragmoceras of Broderip, and the Lituites of Breyn (see [figs. 415], [416.]). The latter is partly straight and partly convoluted, nearly as in Spirula.