FROM THE INFERIOR OOLITE. 261 



Galerites kadiatus. Valenciennes, Encycloped. Methodique, tab. 153, figs. 1, 2 



(Explication des Planches). 



— depressa. Koch and Dunker ? Norddeutschen Oolithgebildes, p. 40, tab. 4, 



fig. 2 a, b, 1837. 

 Holectypus depressus. Bronn and Romer, Lethsea Geognostica, 3" e Auflage, Band ii, 



p. 148, tab. 17, fig. 5 a, b, 1851. 

 Discoidea depressa. Agassiz, Prodromus, p. 86, 1837. 



— — Agassiz, Echinodermes Foss. de la Suisse, part i, p. 88, tab. 13, 



figs. 7—13, 1839. 



— — Desor, Monographic des Galerites, p. 65, tab. 10, figs. 4 — 12, 



1842. 

 Holectypus depressus. Desor, Catalogue raisonne, Ann. des Sc. Nat., 3 me serie, torn, vii, 



p. 145, 1847. 



— — Albin Gras, Oursins Fossiles du departement de l'Isere, p. 41, 



1848. 



— — Wright, Annals and Magazine of Natural History, 2d series, 



vol. ix, p. 94, 1851. 



— — Forbes, in Morris's Catalogue of British Fossils, 2d edit., p. 82, 



1854. 

 Desor, Synopsis des Echinides Fossiles, p. 169, 1857. 



Test thin, hemispherical, sometimes conoidal, more or less depressed; circumference 

 circular, or sub-pentagonal, and slightly contracted posteriorly ; base flat, or a little 

 concave ; mouth central ; peristome nearly equally decagonal, with reflected margin ; 

 anal opening large, pyriform, occupying nearly all the space between the mouth and 

 the border; ambulacral areas lancet-shaped, with from six to eight rows of tubercles 

 at the circumference, arranged in two oblique rows ; inter-ambulacral areas with from 

 sixteen to twenty rows of tubercles, which form a single row on the centro-sutural half of 

 each plate, and two or three rows on the zonal half of the same ; apical disc small, four 

 genital plates nearly equal sized, the right anterolateral large, with the madreporiform body 

 projecting into the centre of the disc. 



Dimensions. — Cornbrash specimen. Height, nine tenths of an inch ; transverse 

 diameter, two inches and two tenths of an inch ; antero-posterior 

 diameter, two inches and two tenths. 

 Inferior Oolite specimen. Height, seven tenths of an inch ; transverse 

 diameter, one inch and a quarter ; antero-posterior diameter, one 

 inch and seven tenths. 



Description. — This is one of the most ubiquitous Echinites of the Oolitic rocks, and 

 as its synonymy shows, has been long known to naturalists. In different formations 

 it attains various degrees of development, being small in the Inferior Oolite, but large in 

 the Cornbrash, as shown by the measurement of the specimens from these two stages. 



The form is sub-conoidal, or more or less depressed ; the circumference is circular, or 

 sub-pentagonal, with the postero-lateral border a little compressed, and the single 



