116 



OOLITIC FOSSIL ASTERIADvE. 



examined and compared with the various modifications of form and structure which a 

 number of specimens of the same species often exhibit after an attentive study thereof. 



The rays in Astrojyecten Scarburtjensis taper to an acute point (fig. 2 a), the borders 

 are shghtly convex, and there are about fifty ossicles around the margin of each ray; the 

 ossicula are quadrate, much rounded, and have their surface covered with numerous small, 

 close-set, granules (fig. 2 c); the ambulacral valleys are wide, and the ambulacral bones are 

 elongated and quadrate (fig. 2 b) ; the upper and under marginal plates form well-marked 

 prominences on the border, when examined in profile, as shown in this figure ; a few small 

 discal ossicles occupy the intermarginal spaces of the rays. 



Locality and Stratigraphical jjosifiun. — This specimen was discovered by Mr. Peter 

 CuUen in the Gray Limestone near Scarborough. It belongs to the cabinet of my friend 

 John Leckenby, Esq., F.G.S. 



C. — S])ecies from the Stonesjield Slate. 



ASTROPECTEN CoTTESWOLDI^E, Buck. PI. IX, fig. 3 a, b, c, fig. 4 ; PI. X, fig. 1 a, b, c, 



d, and fig. 3 a, b, c, d. 



AsTERiAS CoTTESWOLDi.K, BucJimaii. MurcMsoii, Geo], of Cheltenham, 2ndecl., tab. iii, 



fig. 5, p. 94, 184.5. 



AsTROPECTEN CoTTESWOLDi^, Forbes. Mcmoirs of the Geol. Survey, p. 479, 1848. 



— — Forbes. Morris's Catalogue of British Fossils, 2ncl ed., 



p. 72, 1854. 



— ■ — JFriffht. British Association Reports, vol. for 18.56, 



p. 402. 



Body flat, rays five, elongated, tapering to an acute point, border of the rays straight, 

 intermediate angles obtuse ; dorsal marginal plates quadrate, upper surface convex, and 

 covered with small granules ; ventral marginal plates spiniferous on their posterior borders ; 

 upper surface of the disc provided with five oblong, bilobed eminences, having two 

 internal rows of serrated processes ; a series of similar bilobed bones, diminishing in size 

 towards the apex, occupy the middle of the rays, with which the discal eminences 

 appear to be continuous; madreporiform tubercle large, excentral, with fine radiating lamellae. 



Dimensiojis. — Diameter of the body, from three to four inches ; the proportionate 

 diameter of the disc to that of the body is as one to three and a half. 



Descrijjtion. — This beautiful Star-fish is sometimes found in fine preservation on slabs 

 of Stonesfield slate. The flat body is provided with five elongated rays, which gradually 

 taper to an acute termination ; the border of the ray is quite straight, and contains fifty -five 



