114 



FOSSIL OOLITIC ASTERIAD^. 



Descrijition. — Rays short in proportion to the rather broad, flat body, triangularly 

 lanceolate, with very straight sides and pointed extremities.' The angles formed by their 

 junction with each other and the body are obtuse. Their margins are bordered by regular 

 series of nearly equal square plates, decreasing but slightly as they approach the apex. 

 The length of each ray is about equal to the diameter of the disc. There are about 

 eighteen marginal plates in each row. The. surface is covered by quadrate tesselations, 

 indicating the arrangement of the plates, which probably, when the animal was alive, l)ore 

 tufts of paxillse or coronated spines. The specimen measures two inches in diameter. 



Affinities and differences. — Asfropccten PhiUipsii, Forb., is probably its nearest fossil 

 ally, but the form and characters of its surface distinguish it conspicuously from any 

 other British member of its genus. 



Locality and Stratigrapldcal position. — This species was discovered in the marlstone 

 of Yorkshire ; the original specimen, which I have not seen, nor can I discover in whose 

 possession it now is, was figured and described by Professor Forbes from an example in 

 the late Marchioness of Hastings' collection ; I have therefore adopted entire my lamented 

 colleague's description of this specimen. The other example (PI. VI, fig. a,h)\ found 

 on a slab of marlstone, from Boulby, near Staithes, associated with Uraster carinaius, 

 Wr. ; this specimen belongs to my friend, John Leckenby, Esq., F.G.S., and is now in his 

 cabinet. Fig. 4 a shows the under surface of the Star-fish, and fig. 4 b the angular 

 ossicles near the base of the rays ; fig. 4 b, the ambulacral valleys, with the biserial 

 tentacule pores and numerous quadrate plates, arranged in a tesselated manner. 



B. — Species from the Inferior Oolite. 



AsTROPEOTEN Leckenbyi, Wriglit. PI. VII, fig. \ aj), c. 



Rays five, elongated, borders straight, intermediate angles very obtuse, border thick ; 

 marginal plates quadrate, elongated transversely, surface closely covered with large 

 granules ; madreporiforra tubercle lai'ge, button-shaped, opposite one of the intermediate 

 angles. 



Descrip)tion. — The border of this Astropecten is formed of thick marginal plates, of a 

 quadrate form, the transverse diameter of which is twice as much as the length ; their 

 surface is covered with large granules, arranged in a quincuncial order, as shown in 

 fig. 1 c. The rays are all more or less broken, consequently the entire number of marginal 

 plates cannot be ascertained ; in the most perfect ray remaining there are tliirty-four 

 plates. As the under surface of this Star-fish is immoveably fixed to the matrix, its upper 



