- a. Turrilites costatus. Chalk marl.
- b. Same, showing the indented border of the partition of the chambers.
Fig. 197.
- a. Belemnites mucronatus.
- b. Same, showing internal structure.
Maestricht, Faxoe, and white chalk.
Among the brachiopoda in the white chalk, the Terebratulæ are very abundant. These shells are known to live at the bottom of the sea, where the water is tranquil and of some depth (see [figs. 198], [199], [200],[ 201.]). With these are associated some forms of oyster (see [figs. 202.] and [204.]), and other bivalves ([figs. 203], [205], [206], [207], [208.]).
Fig. 198.