FROM THE CORAL RAG. 249 



I have made the above extract entire from Professor Forbes's note on undescribed 

 species of Acrosalenia, Decade IV, pi. 3, of the ' Memoirs of the Geological Survey.' 

 After a careful comparison of the type specimen in the Museum of Practical Geology, 

 in Jermyn Street, with a large series of Acrosalenia spinosa, I have in my collection, from 

 the Great Oolite of Minchinbampton, and of Ranville, Calvados, and from the Cornbrash 

 of Wiltshire, I can detect no persistent specific character in A. radiata ; the upper inter- 

 ambulacral tubercles are larger than in many specimens, but in others, the same gradual 

 diminution observed in A. radiata prevails in a large series ; in fact, the links between a 

 sudden diminution and a gradual diminution are abundantly supplied ; for these reasons 

 I consider A. radiata, Forbes, as a synonym of A. spinosa ; the structure of the apical 

 disc, and of its single sur-anal plate, are the same in both. 



Acrosalenia aspera, Agassiz. 



Professor M'Coy has entered this species in his list of Mesozoic Radiata,* contained in 

 the Geological Collection of the University of Cambridge, giving as the localities of the 

 species " Great Oolite, Minchinhampton, Inferior Oolite, Dundry." Having seen this 

 specimen, I can state that I believe it to be a small A. hemicidaroides from Minchinhamp- 

 ton. The original Acrosalenia aspera, Agass., was found by M. Gressly in the Kimme- 

 ridge Clay of Banne, near Porrentruy, only a single specimen of which is known. I 

 have never seen an urchin from Minchinhampton, nor Dundry, which resembled this Swiss 

 species. 



D. Species from the Coral Hag. 

 Acrosalenia decorata, Haime. PI. XVII, fig. 1 a, b, c, d, e, f, g, h, m. 



Milnia decorata. Haime, Annales des Sciences Naturelles, 3 me eerie, torn, xii, 



Zoologie, 1849, pi. 2, figs. 1—3, p. 217. 



Acrosalenia decorata. Wright, Annals and Magazine of Natural History, 2d series, 



vol. ix, p. 81, 1851. 



— — Forbes, Memoirs of the Geological Survey, Decade IV, pi. 3, 1852. 



— — Cotteau, Notes surles Echinides de l'etage Kimm6ridgien du dep. 



l'Aube, Bulletin Soc. Geol. de France, 2d serie, torn, xi, p. 355, 

 1854. 



— — Forbes, in Morris's Catalogue of British Fossils, 2d edit., p. 69, 



1854. 



— — Desor, Synopsis des Echinides Fossiles, p. 143, 1856. 



— — Cotteau, Etudes sur les Echinides Fossiles, p. 322, 1856. 



* 'Annals and Magazine of Natural History,' 2d series, vol. ii, p. 419. 



