2 



BRITISH FOSSILS. 



This view, however, is not taken by continental authors, though 

 originally held by Agassiz, who, in his Systematic Catalogue, regarded 

 the Nucleolites depressa of Brongniart as one with that author's JV. cas- 

 tanea, and placed them both under the name Galerites castanea. Des- 

 moulins, in his " Tableaux Synonymiques," enumerates both as 

 distinct, and places them in the genus Pyrina. Desor, in his Mono- 

 graph of the Galerites^ identifies G. castanea with the Galerites rotho- 

 magensis of Agassiz's Catalogue, but places in the genus Pyrina the 

 Nucleolites depressa of Brongniart. In the " Catalogue Raisonne des 

 Echinides" the authors keep the G. rothomagensis and G. castanea under 

 the latter name, and refer to the figures of the former and descrip- 

 tions of both species in E. Sismonda's " Memoirs on the Fossil Echinidae 

 of Nice." In that work the figures of G. rothomagensis accord excel 

 lently with the British species before us, and the author remarks that 

 the distinctions between the two are very slight indeed : " Non e che 

 per leggerissime modificazioni dei principali caratteri, che questa specie 

 puo staccarsi dal Galerites castanea, di cui la tutto I'abito." Yet, 

 assuredly, the Italian species is much closer to the original figures of 

 " Nucleolites^ depressa than to those of Galerites castanea. Such, in 

 brief, is the history of our species, which, in England however, is 

 not likely to be confounded with any other member of its genus, or to 

 be regarded as a member of any other sub-genus than that to which 

 we have assigned it. 



The figures of the Galerites Icevis of Agassiz in Desor's Monograph 

 have all the appearance of being representations of a variety of this 

 species w^hich occurs at Warminster. M. Desor describes and figures 

 it from the only specimen he had met with — one in the collection of 

 M. Deshayes, from cretaceous strata in France. Mr. M^Coy, in his 

 additions to Morris's Catalogue, mentions both Galerites castanea and 

 Galerites Icevis as British species. 



British specimens of this species almost all belong to the small 

 variety, and those which I have examined and figured are of an ovate 

 or suborbicular form, inclining to obtusely pentagular or hexangular. 

 They vary much in the degree of tumidity and height as compared 

 with the length and breadth, being sometimes nearly convex on the 

 summit, at others depressed. The obscure angles, when they are five, 

 correspond to the ambulacral areas ; when there is a sixth, it is in the 

 centre of the posterior or odd interambulacral space. The inter- 

 ambulacral areas exceed the breadth of the ambulacral by three-fifths 

 on the middle of the sides. The sides are so rounded that their most 

 tumid portions are central or sub-central. The base is flattened in the 

 centre, rounded off at the sides, and has the mouth nearly in its 

 middle. The mouth is rather small, rounded, and obscurely decago- 



