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] [296] Ibid. p. 332. Specimens of these Goniasters are sometimes met with attached to a nodule of flint, in an extraordinary state of freshness; sharp imprints of the external surface, the skeleton having perished, are also found in flints, and, rarely, casts in pyrites. The whetstone of Dorsetshire often bears distinct moulds of Goniasters! I have found ossicula of this form of Star-fish in the London Clay of the Isle of Sheppey. Asterias. _Lign. 99._--The animals of this genus, of which the common Star-fish is the type, are stellate in form; the rays are flat, and extend from the body, of which they are a prolongation--not mere appendages. They have deep grooves or furrows bordered by marginal plates, which are continued to the extremities. The Lias of Germany has yielded several species of Asterias; one of which is figured, _Lign. 99_. A very large species occurs in the Cornbrash of the Oolite of England. A magnificent specimen of _Asterias arenicola_ (Goldfuss), from the calcareous grit, near Pickering, Yorkshire, measuring 10-1/2 inches from the extremity of one ray to that of another, is figured in the London Palæontological Journal, pl. xvii. The same work contains admirable figures of _Ophiura Egertoni_, and _Oph. senatu_ in flint, pl. xix.; _Oph. Milleri_ in Staithes marlstone, and _Oph. Murravii_, pl. xx.; and two specimens of _Oph. Milleri_ on the same slab of Lias from Staithes, near Whitby, pl. viii.