§ 23. STAR-FISHES OF THE CHALK. 327 



subdivided into a few branches, were formed of little bones. 

 or ossicula ; the whole was invested with a muscular tissue, 

 or membrane. When floating, the creature could spread 

 out its tentacula like a net, and by closing them, seize its 

 prey and convey it to the mouth. This figure {Lign. 61) 

 is restored from specimens which separately exhibit the 

 parts here represented.* 



22. Star-fishes of the chalk. t — Of the radiated 

 animals termed Asterias, or star-fish, several genera occur 

 in the English chalk and greensand, and in the cre- 

 taceous strata of the Continent. In the Sussex chalk, 

 beautiful examples of the Goniaster, or cushion-star, 

 have been found ; but they are more frequently met with 

 in the white chalk near Gravesend, Northfleet, Purfleet, and 

 other Kentish localities. The cabinet of the Marquess of 

 Northampton contains exquisite specimens of Goniaster, 

 partly imbedded in flint ; similar fossils have been ob- 

 tained from the siliceous rock, called whetstone, of Devon- 

 shire. Several fine examples of an undescribed Asterias of 

 the radiated type, with elongated rays, and large ossicula, 

 have been collected from the Dover chalk : and a splendid 

 specimen from that locality, as perfect as if recently dredged 

 up from the sea, is in the beautiful collection of Mrs. Smith, 

 of Tunbridge Wells. Detached ossicula are very abundant 

 in some of the strata ; and there are layers of the grey or 

 lower chalk, wholly made up of the debris of star-fish, 

 minute spines of echini, &c. 



23. Echixites.J — Those remarkable animals, the Echini, 

 or sea-urchins, are too well known to require particular 

 description. Their spherical shell, or case, is composed of 



* There is another species often found with the above, in which the 

 plates are covered with rugous markings : it is the 31. ornatus of the 

 late Mr. Miller. 



f Medals of Creation, vol. i. p. 332. 



+ See Medals of Creation, vol. i. chap. xi. p. 340. 



