EROM THE CORALLINK OOLITE. 385 



small specimen from the clay band (fig. 1), is the only example I have yet seen which 

 shows the basal surface, now j)ublishecl in fig. 1 h, for the first time. 



Locality and Slrafif/raphical position . — This nrchin has hitherto been collected only from 

 the Coralline Oolite of Malton and Scarborough, although I have seen fragments of it in the 

 Ayton quarries. It is usually imbedded in a white Oolitic limestone, firmly attached by the 

 base in consequence of its inequalities, and, having the upper surface exposed, the matrix 

 is usually removed by scraping ; but the Oolitic grains frequently indent the surface of the 

 plates. This species was formerly more abundant, than now, probably because the vein 

 containing the fossil was worked more in former years. Almost all the specimens are 

 fractured and crushed, and it is rare to find one which preserves the true type-form of the 

 species. For the same reason w^e seldom observe the ridges which radiate from the 

 disc to the mouth-opening, on the surface of each inter-ambulacral segment. I have 

 never seen them distinctly, but in the two specimens I have figured, where they un- 

 doubtedly exist, and form a good diagnostic character for the species. 



History. — It was first figured and described as Eclnnites suljulatus, by Young and 

 Bird, in their ' Geological Survey of the Yorkshire Coast/ and afterwards by Professor 

 Pliillips, as Clypeus emaryinatus, in his ' Geology of Yorkshire ;' the first name must 

 therefore be retained. Professor Forbes gave a diagnosis of the species in his ' Notes on 

 British Oolitic Nucleolites/ in the first decade of his ' Memoirs of the Geological 

 Survey.' It was imperfectly described, for want of specimens, in my ' Memoir on the 

 Cassidulidaj of the Oolites ;' but is now figured, with full details, from two fine speci- 

 mens, for the first time. 



