The constituent substance of the ossicula and plates of the Bradford Encrinite is calcareous, and has an oblique fracture; the colour is generally a light ochre, or a bluish grey.[276]
[276] Pict. Atlas, pl. 1. contains figures of the Bradford Encrinites.
APIOCRINITE OF THE CHALK.
Apiocrinus ellipticus. [Lign. 93.]—Detached ossicula of this small encrinite are abundant in the White Chalk; the receptacle is known to the quarrymen by the name of "bottle." The pieces composing the column are cylindrical in the upper part, and elliptical and angular in the lower, and are articulated by a transversely-grooved surface. The two upper joints are enlarged, and support the receptacle, which is smooth and round (fig. 1). The column has articulated side-arms, and the base numerous jointed processes of attachment, which, when found apart from the column, have been mistaken for a distinct type, and named "Stag's-horn Encriniter."[277] The specimens figured [Lign. 93], show the essential characters of this crinoid; when perfect, this species must have borne a general resemblance to the Pear Encrinite of Bradford.
[277] Pict. Atlas, pl. xlvii. fig. 31, p. 113. In the same plate there are figures of several specimens of detached portions of the stem of this species from the Kentish Chalk.
Lign. 93. Apiocrinites. Chalk, Lewes.
| Fig. | 1.— | Apiocrinus ellipticus, × 3. |
| 1a.— | Part of the elliptical portion of the column, with a side-arm. | |
| 1b.— | Portion of the same, magnified. | |
| 1c.— | The articulating surface of an ossicle. | |
| 2.— | Ossicle of A. flexuosus. (M. D'Orbigny.). | |
| 3.— | Portion of the cylindrical stem. |
Bourqueticrinus (D'Orbigny). [Lign. 91, fig. 11.]—Detached ossicles of other species belonging to the same genus, or to allied genera, are frequently met with in the Kentish and Sussex chalk. A common form is that figured in [Lign. 91], which is part of the receptacle of a crinoid, named as above; it differs from the other Apiocrinites of the chalk in the articulating surfaces of the ossicles not being radiated, and in the receptacle, which is small and pyriform, not having a distinct cavity; there is only a median canal, which is seen in a vertical section: but the entire structure of the summit does not appear to be shown in any specimens hitherto observed.