Lign. 98. Fossil Star-fish. Chalk, Kent. Goniaster Mantelli. (sp Forbes.[293])
[293] Dixon's Cret. Foss. p. 332.
The detached ossicula of the skeletons of Cushion-stars are frequent in the White Chalk; and the large central bone, the madreporiform tubercle, which is present in the dorsal aspect of all star-fishes, is large, and therefore often observed, and may be easily mistaken for the base of a crinoidean receptacle. The layers in the Sussex Chalk composed of the exuviæ of star-fishes, as previously mentioned, are chiefly made up of ossicula of goniasters.
There are two species not uncommon in the Chalk, of which portions may generally be obtained from the pits near Gravesend; and occasionally very fine examples of the entire goniaster are met with. Mr. Dixon's work contains figures of several exquisite fossils of this kind. These organic remains were familiar to the early collectors: Mr. Parkinson figures several in Org. Rem. vol. iii. pl. i. and ii.[294]
[294] Pict. Atlas, pl. liii.
Goniaster Hunteri ([Lign. 97]), has the body obtusely pentagonal, and the sides nearly straight; the superior intermediate marginal plates are four, equal, broadly oblong, coarsely mamillato-punctate; the ossicula of the disk hexagonal.[295] This species is common in the upper chalk.
[295] Prof. Forbes, Dixon's Cret. Foss. p. 331.
In Goniaster Mantelli, [Lign. 98], the body is pentagonal, but the sides are curved, with projecting angles; the ossicula of the disk are punctated. The superior intermediate marginal plates are oblong, narrow, punctate, marginate, and six in number.[296]