A Pictorial Atlas of Fossil Remains, consisting of coloured illustrations selected from Parkinson's "Organic remains of a former world," and Artis's "Antediluvian phytology."

by Gideon Algernon Mantell

Plate LXVII.

PLATE LXVII.

Fossil Shells of Brachiopoda, &c.

Fig. 1. A species of Radiolites (R. agariciformis, of M. D'Orbigny), from the Cretaceous strata of France. This genus is only known in a fossil state; it belongs to the same group of shells (order, Rudistes) as the Spherulites and Hippurites: the lower valve is conical, and much larger than the upper, which is slightly convex; it is deeply channelled longitudinally.

Fig. 2. Smooth valve of a species of Corbula (Corbula gallica, of Lamarck); abundant in some of the Eocene deposits of the Paris basin.

Fig. 3. A single valve; the inner surface is shown in the figure, of a remarkable genus of shells (Crania personata, of Lamarck), frequently occurring attached to Echinites and other bodies of the white chalk.

Fig. 4. A species of Terebratula (T. diphya, of Lamarck). The shells of this genus belong to that division of mollusks termed Brachiopoda (arm-feet), from their having internally two spiral fleshy arms developed from the sides of the alimentary orifice. These organs are supported by shelly processes, curiously modified in different genera, which often occur in a fossil state. Although the fossil Terebratulæ are very numerous, the recent species are but few, and are inhabitants of the seas off Australia. They form two natural groups; in the one the shells are smooth, but perforated all over with minute openings or foramina; and these are often filled with a dark substance, which is the carbonized soft parts: in the other division the shells are plicated or furrowed, and are not foraminiferous.[62] The Spirifers, another group of Brachiopoda, have a pair of internal spiral appendages.