Fig. 6. A Ventriculite from a gravel-pit; the markings are produced by the exposed and partially abraded outer integument, which in perfect examples consists of a regular net-work of sub-cylindrical fibres. Fig. 7, is a transverse section of a Siphonia (_Siphonia pyriformis_ of Goldfuss). Fig. 8. A nearly perfect specimen of a similar fossil. In fig. 7, are shown sections of tubes passing from the periphery to the centre; in fig. 8, the central aperture of the cavity of the bulb, and part of the stem, are displayed. Figs. 9, & 10, are imperfect specimens of Choanites: fig. 10, is a vertical section showing the central cavity and the connected tubes. Fig. 11, is another example of _Siphonia pyriformis_. Fig. 12, a vertical, and fig. 13, a transverse section, of the same species of Siphonia. Fig. 14. A small turbinated calcareous spongite from Switzerland. Fig. 15. The appearance of the animal membrane exposed by immersion of the fossil (fig. 14), in diluted hydrochloric acid. [Illustration: Plate XLIII.] PLATE XLIII. Fossil Corals, and other Zoophytes. Figs. 1, 2, 3, & 4, are representations of different aspects of a simple coral (_Fungia polymorpha_, of Goldfuss); the locality is uncertain. Fig. 1, the base; fig. 2, a magnified representation of part of the same; fig. 3, magnified view of part of the lamellated surface of fig. 4. Fig. 5. The nature of this fossil is not obvious; it may be a rolled Siphonia. Fig. 6, is a fine specimen of a Siphonia (_Jerea pyriformis_, of Lamouroux). At both extremities the apertures of the numerous tubuli are seen. Figs. 7, 8, & 9, are varieties of the same species of fossil sponge (_Scyphia articulata_, of Goldfuss), from Switzerland. Fig. 10. A spongite of a very peculiar form. Fig. 11. A spongite investing a fossil shell (_Nerita_), from Faringdon. Fig. 12, is an imperfect specimen of a Ventriculite (_Ventriculites alcyonoides_, of Mantell), from the chalk of Wiltshire. Fig. 13. A calcareous spongite which has been immersed in dilute hydrochloric acid to show its structure. Fig. 14. A pebble deriving its shape from a zoophyte apparently related to the Ventriculites (_Spongites labyrinthicus_, of Mantell). The aperture at the base has arisen from the decomposition of the process of attachment. Fig. 15. A pebble enclosing part of the base of a Ventriculite; the circular spots on the large end are sections of the ramifications of the stirps or base of the zoophyte; for this figure and the following are drawn in an inverted position. Fig. 16, is a similar fossil, split vertically, and showing the enclosed stem of the Ventriculite. [Illustration: Plate XLIV.]