FROM THE UPPER GREENSAND. 99 



in the Chloritic Marl, full of green specks of iron, at Chard, associated with Catopygus 

 carinatus, Goldf., Discoidea suhiiculus, Leske, Pseudodiadema ornatum, Goldf., P. 

 variolare, Brong., with Ammonites splendens, Sow., A. varians, Sow., and other forms 

 characteristic of the Upper Greensand formation. The specimens from Warminster, in 

 the Museum of the Royal School of Mines, and in the Collections of Mr. Soper and Mr. 

 Cunnington, Devizes, were found in the Upper Greensand with P. Michelini, Agas., and 

 P. BenetiicB, Forb., and other common Upper Greensand forms, as Catopygus carinatus, 

 Goldf., Salenia petalifera, Agass., and Goniopygus peltatus, Agas., &c. &c. 



Foreign Distribution. — Geraudot (Aube) ; Perte du Rhone (Ain) ; Clars, EscragnoUe 

 (Var) ; very common in the Etage Albien (Cotteau). 



History. — First figured by Professor Agassiz in 1840, the large forms as Biadema 

 Rhodani, the smaller as D. Lucce. After much confusion it was discovered that these 

 forms are identical. Professor Forbes, from not possessing types of Pseudodiadema 

 Rhodani, named the large form Biadema pustulatum, and the small ones from War- 

 minster B. Besori ; this nomenclature was adopted by Dr. S. P. Woodward, in 1856, in his 

 " Additional Notes on British Fossil Diadems," published in Decade V of the ' Memoirs 

 of the Geological Survey.' M. Cotteau, in 1863, has given admirable figures, and a 

 most correct description of the species, which my observations confirm in all their details. 



Pseudodiadema Michelini, Agassiz. PL XIX, figs. 2, a—f. 



DiADEMA Michelini, Agassiz. Catal. Syst. Ectyp. foss. Mus. Neoc, p. 8, 1840. 



— — Agassiz et Desor. Catal. rais. des Echinides, Ann. 



Sc. Naturelles, 3= ser., t. vi, p. 347, 1846. 



— — Bronn. Index Palseont., p. 418, 1848. 



— — Sorignet. Ours. foss. de dep de I'Eure, p. 25, 1850. 



— — D'Orbigny. Prod. Paleont. strat., t. ii, p. 179, 1850. 



— BoNEi, Forbes. In Morris's Catalogue of British Fossils, 2nd ed., 



p. 76, 1854. 



— — Woodward. Mem. of Geol. Survey, Decade V, explan. of 



pi. ii, 1856. 

 Pseudodiadema Michelini, Desor. Synopsis des l5chinides fossiles, p. 72, 1856. 

 DiADEMA Michelini, Pictet. Traite de Paleont., 2' ed., t. iv, p. 245, 1857. 



Pseudodiadema pulchellum, Cotteau. fichinides nouv. ou peu connus (Revue de 



Zoologie), p. 3, pi. i, fig. 7—9, 1857. 

 Pseudodiadema Michelini, Bujardin et Hup6. Hist. Nat. des Zoophytes, Echino- 



derm., p. 499, 1862. 

 — — Co^/eaw. Paleontologie FranQaise, Terrain Cretace', p. 476, 



pi. 1114, 1864. 



Biagnosis. — Test circular, or slightly pentagonal, depressed ; base flat, inflated at the 

 margin, concave towards the mouth ; ambulacral areas large, two rows of prominent 



