FROM THE WHITE CHALK. 



267 



Affinities and Differences. — The wide test, deep ambulacra, and inclined upper surface 

 distinguish this Urchin from all its congeners ; and likewise from the Micrasters with 

 which others have been often confounded. 



I dedicate this fine species to my esteemed friend M. De Loriol, the learned author of 

 the ' fichinologie Helvetique/ whose assiduous studies in Palaeontology have borne such 

 ample fruits. 



Locality and Stratigrapldcal Position. This species has been collected from the 

 Upper Greensand, near Warminster and Devizes, Wilts. 



Epiaster gibbus, Lamarck, 1816. PI. LXIH, fig. 1, a — k. 



Spatangus gibbus, 



— COB-ANGUINUM, 



— GIBBUS, 



Lamarck. Animaux sans Vertebres, t. iii, 



p. 32, 1816. 

 Deslo7tff champs. Enc. Method., p. 689, 



pi. 156, figs. 4— 6, 1824. 

 Gold/uss. Petr. Germanise, tab. xlviii, fig. 4, 



p. 155, 1824. 

 Defrance. Diet. Sc. Nat., t. 1, p. 94, 1827. 

 Woodward. Geol. of Norfolk, pi. v, fig. 8, 



1833. 

 De Blainville. Manuel d'Actin., pp. 203, 653, 



1834. 

 Grateloup. Oursins Foss. (Dax), p. 71, 



1836. 

 Desmoulins. Etudes sur les Echinides, p. 402, 



1837. 

 Edwards. Anim. sans Verteb., t. iii, p. 331, 



1840. 

 Agassiz. Catal. Syst., p. 129, 1847. 

 Hebert. Etudes sur les Terr. Cretaces ; Mem. 



Soc. Geol. France, 2e ser., t. v, pi. xxix, 



fig. 16, 1854. 

 Desor. Synopsis Echid. Foss., p. 365, 1858. 

 Forbes (pars). Mem. Geol. Surv., dec. iii, 



pi. X, 1850. 

 Forbes. In Dixon's Geol. of Sussex, p. 342, 



pi. xxiv, figs. 5, 6, 1850. 

 COE-ANGUINUM var. GIBBUS, Morris. Brit. Foss., 2nd ed., p. 83, 1854. 



— d Orbigmj (pars). Paleont. Fran9aise Terr. 



Cret., t. vi, p. 207, 1855. 



MiCKASTER CORDATUS, 



— GIBBUS, 



— COR-ANGUINUM, 



— GIBBUS, 



Diagnosis. — Test cordiform, very high, and almost conical ; sides convex and 

 carinated. Ambulacra slightly depressed ; anteal sulcus shallow above and grooving the 

 anterior border ; posterior margin acuminated and truncated obliquely inwards. Vent 



