ASTROPECTEN. 



115 



surface alone is exposed (fig. 1 h) ; the tliickness of the marginal plates is well shown in 

 section here. The remains of the large madreporiforra body occupies an excentral 

 position, on the upper surface, opposite one of the intermediate angles (fig. \ a) \ as none 

 of the structure of the intermarginal surface of the body is preserved, the character of the 

 paxillaB is unknown. 



Locality and Siraligrajjliical position. — This Star-fish was discovered in a boulder of 

 Gray Limestone on the shoi-e, by the White Nab, near Scarborough. The rock was described 

 by Prof. Phillips as Great Oolite, but the zoological character of its fossils proves that the 

 species are identical with the fauna from the zone of Ammonites Humphriesianus of the 

 Inferior Oolite, to which I have referred the Gray Limestone in my memoir.^ 



Astropecten LecJcen/jyi was here associated with Ammonites Humphriesianus, Sow., 

 A. Blagdeni, Sow., A. Braclcent)ridf/ii, Sow., and A. Parkinsoni, Sow., together with twenty 

 species of Gasteropoda and forty species of Conchifera, all of which are, for the most part, 

 characteristic of the Liferior Oolite. Bhabdocidaris maxima, Bsendodiadema depressum, 

 Ag., P. vagans, Phil., Astropecten Scarhurgensis, and Opiiiura Murravii, Forb., are like- 

 wise found with it in the same bed of Gray Limestone. 



This beautifid specimen is now preserved in the Scarborough Museum, and is the only 

 example of the species that has yet been found. 



Astropecten Scarburgensis, Wright. PI. VII, fig. 2 a, h, c. 



Rays five, elongated, tapering to an acute point, intermediate angles acute ; border 

 of the rays convex ; marginal plates thick, quadrate . surface covered with small, close-set 

 irregular granules. 



Dimensions. — Transverse diameter from ray point to ray point, three and a half inches ; 

 diameter of the disc across the marginal plates, one inch. 



Description. — In many respects this species resembles A. Leckenbgi, but it difters from 

 that form in having the intermediate angles more acute, the borders of the rays convex 

 insteadof straight, and the surfaceof the marginal plates covered with small irregular granules. 

 As both these Star-fishes are unicuras, I write with much reserve regarding their differences, 

 knowing how often external characters are found to blend into each other when they are 



* 'On the Subdivisions of the Inferior Oolite in the South of England,' and 'Quart, Jour. Geol. 

 Soc.,' vol. xvi, p. 29. 



