OPHIURA.
Ophiura. [Lign. 97, fig. 1.]—Several species of this genus, which is distinguished by the long, slender, serpent-like arms, and the circular disk covered with plates and spines, have been found in a fossil state: one species was discovered in the Lower Silurian deposits by Prof. Sedgwick, and other forms have been obtained from all the succeeding formations. The Lias near Lyme Regis and Charmouth has yielded many beautiful examples of Ophiura Egertoni. Professor John Phillips has figured a species (Oph. Milleri, Geol. York, pl. xiii.) from the marlstone of Yorkshire, and a species from the Oxford Clay has been described as Ophiura Prattii. In the Cretaceous formation, remains of several species have been found. The first specimen from the Sussex Chalk that came under my notice, was discovered many years since, by my son, in a quarry at Preston, near Brighton; the rays were admirably preserved, as shown in the portion figured in Lign. 97. An example of this species, with the disk entire, and portions of five arms, was found by Henry Catt, Esq. and is represented in pl. xxiii. fig. 2, of Mr. Dixon's work.[292]
[292] Three plates are devoted to the Cretaceous Star-fishes: the descriptions by Prof. E. Forbes comprise twenty-five species, belonging to the genera Oreaster, Goniaster, Stellaster, Arthraster, and Ophiura, all from the Chalk of Sussex and Kent.
Lign. 97. Fossil remains of Star-fishes.
| Fig. | 1a. | —Part of the ray of Ophiura serrata; nat. Chalk, Preston. (Mr. Walter Mantell.) |
| 1. | —Portion of the same magnified. | |
| 2. | —Goniaster Hunteri. Chalk. Gravesend. |
GONIASTER—ASTERIAS.
Goniaster. Lign. [97] and [98].—The star-fishes of this genus, popularly called Cushion-stars, are of a pentagonal form, and have a double series of large marginal plates, bearing granules or spines; the latter are seldom preserved in the fossils. The upper surface is nodulose.