FROM THE GREY CHALK. 105 



British Museum, and my cabinet. I have examined a specimen from the Red Chalk of 

 Hunstanton Cliff, belonging to my friend C. B. Rose, Esq., F.G.S., who has most kindly 

 communicated many of his Echinodermata for this work. The specimen figured in 

 PI. XXI, fig. 1, now in my cabinet, was collected from the remarkable bed of Chloritic 

 Marl at Chard, which has yielded so many fine examples of Echinidce. The specimen in 

 the Cambridge Museum is recorded by Professor McCoy as having been collected from 

 the Upper Greensand of Blackdown. Many of the specimens sent me as P. Carteri 

 by my friend Mr. J. Walker, F.G.S., and collected by him from the copvolite beds of the 

 Upper Greensand near Cambridge, are undeniable specimens of P. ornahun. 



Foreign Distribution. — Frcmce. — Rouen, Mountain of St. Catherine, Seine-Inferieure ; 

 Vimoutiers (Orne), in the Btage Ccnomanien, where it is rare. Germany. — Essen-on-the- 

 Ruhr, Westphalia, whence Goldfuss's type specimen was obtained. 



Histori/. — This Urchin was first figm'ed and described in the ' Petrefacta Germanise' by 

 Goldfuss, in 1826, under the name Cidarites ornatus. Professor Agassiz, in 1836, 

 erroneously referred to this species a small Neocomian form, which was subsequently 

 separated under the name Diadema Bouryueti. In the first edition of the ' Catalogue of 

 British Fossils,' Diadema Benettice was recorded as D. ornatum on the authority of 

 Dr. Woodward. Professor Forbes named the tumid varieties of this Urchin Diadema 

 tumidum, and under this name they are described, from type specimens, in my cabinet 

 (PI. XXI, fig. 1), by Dr. S. P. Woodward, in his " Notes on British Fossil Diadems," con- 

 tributed to Decade V, ' Memoirs of the Geological Survey.' 



PSEUDODIADEMA NoRMANIiE, Cotteaii, 18C3. PI. XXI, fig. 3, a, d. 



PsEUDODiADEMA NoRMANiyE, Cotteau. Paleontologie rran9aise. Terrain Cretace, t. vii, 



p. 4G8, pi. 1112. 



Test of moderate size, subcircular, inflated at the sides, and convex above ; base rounded 

 at the margin, and very concave in the centre ; ambulacral areas wide, with two rows of 

 tubercles, large at the ambitus and small on the upper and infra-marginal regions, sepa- 

 rated by several rows of minute unequal granules ; inter-ambulacral areas narrow, with 

 two rows of primary tubercles, nearly similar in size and development to those of the 

 ambulacra, and numerous small, unequal, secondary tubercles, forming in the infra-mar- 

 ginal region six short series, two on each side, and two in the middle of the primary 

 rows ; mouth-opening lodged in a deep depression. 



Dimensions. — Height six tenths of an inch ; transverse diameter one inch and four tenths. 



Description. — This rare and beautiful Urchin is of medium size ; it has a subcircular 

 form, with broad inflated sides, convex at the upper surface and very concave beneath. The 

 ambulacral areas are wide in the middle, lanceolate in the upper part, and narrow in the 

 infra-marginal region ; they have two rows of primary tubercles, of which two pairs at the 



14 



