ASTROPECTEN. 



139 



ossicles smaller, more numerous, aud more spiniferous ; the crowded rows of spines which 

 bound the ambulacral valleys form a remarkable character in this Star-fish. 



It differs from Astropecten clavaformis, Wr., associated with it in the same formation, 

 in having the border straight, the marginal ossicles small, square, and spiniferous, and in 

 having the rays lanceolate and tapering to a blunt apex. The swelling out of the ray 

 towards the base, and the form and size of the marginal plates in that region, constitute 

 diagnostic characters by which the two forms are readily distinguished from each other. 



Locality and 8trati(jrapMcal Position. — All the specimens at present known have been 

 obtained in the state of moulds from a bed of light-coloured sandstone appertaining to 

 the Kelloway rock, near Leavisham station, on the Whitby branch of the North-Eastern 

 Railway. In Newton Dale there is a fine development of the Middle Oolites, and most 

 instructive sections of Kelloway rock, Oxford Clay, and Calcareous Grit are well exposed 

 on each side of this railway which takes the line of the highly picturesque valley of the Esk. 



The specimen I have figured belongs to the museum of the Yorkshire Philosophical 

 Society. The British Museum, the Museum of Practical Geology, Jermyn Street, London, 

 the Scarborough Museum, and the cabinets of Dr. Murray and John Leckenby, Esq., F.G.S., 

 Scarborough, all contain fine specimens of this Star-fish. 



F. — Species from the Calcareous Grit. 



Astropecten rectus, McCoy. PI. XII. 



Astropecten uecta, M'Coy. Ann. and Mag. of Nat. Hist., 2nd series, vol. ii, p. 408, 

 1848. 



— RECTUS, Forbes. Morris's Catalogue of British Fossils, '2nd cd., p. 73, 



18,)4. 



— — Jl'right. British Association Reports for 18.56, p. 402, 1856, 



— — WriyJit. Monograph of Oolitic Echinodermata, p. 428, 1858. 



Rays five, narrow, elongated, tapering gradually from the angles to the apex, sides 

 straight, bordered by two rows of quadrate marginal plates, averaging in width one third 

 of the ray ; surface covered with small tubercles and a row of larger, spiniferous tubercles 

 on the distal border of each ossicle ; intermediate angles acute ; disc small in proportion to 

 the body, proportionate diameter as two to nine. 



Dimensions. — Diameter of the disc, one inch and nine tenths ; breadth of the body from 

 ray point to ray point, nine inches ; length of a ray from the intermediate angle to the 

 point, four inches and one quarter ; breadth of a ray at the widest part, nine tenths of an 

 inch. 



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