FROM THE INFERIOR OOLITE. 309 



in preference to that of Disaster Agass., by which name the urchins included in this group 

 have been long known to English Geologists through the classical monograph on this 

 genus published by M. Desor, in 1842. 



A. Species from the Inferior Oolite. 

 CoLLTRiTES RiNGENS, Agassiz. PI. XXII, fig. 3 a, h, c, d, e,f,g, /^ i. 



DvsASTEii RINGENS. Ag.issiz, Prodromus, 1" vol., des Mem. de la Societe des Sciences 



Naturelles de Neufchatel, 1836. 

 CoLLYaiTEs RINGENS. Dcsmoulins, 3' Memoires sur les Echinides, p. 368, 1837. 

 Dysaster eingens. Agassiz, Echinoderm. Foss. de la Suisse, 1" partie, p. 5, tab. 1, 



figs. 7—11, 1839. 



— — Agassiz, Catalogus Systematicus, Ectyp. foss. p. 3, 1840. 



— — Desor, Monographic des Dysaster, p. 24, tab. 1, figs. 13 — 17, 



1842. 



— — Agassiz and Desor, Catalogue raisonne des Echinides, Annales des 



Sciences Naturelles, 3" serie, tome viii, p. 33, 1848. 



— EuDESii. Agassiz, Catal. System, Ectyp. foss. p. 3, 1840. 



— — Desor, Monographic des Dysaster, p. 23, tab. 1, figs. 5 — ^12, 1844. 



— SUBRINGENS. M'Coy, Annals Nat. Hist., 2d series, vol. ii, p. 415, 1848. 



— RINGENS. Forbes, Mem. of the Geol. Survey, decade 3, pi. 9, figs. 1 — 10, 



1850. 



— — D'Orbigny, Prodrome de Paleontologie, tome i, p. 289, 1850. 



— — Wright, Annals of Nat. Hist., 2d series, vol. ix, p. 207, 1851. 



— — Cotteau, Etudes sur les Echinides Fossiles, p. 46, pi. ii, figs- 



10—13, 1852. 



— — Forbes, in Morris's Catalogue of British Fossils, 2 ed., p. 78, 1854. 

 CoLLYRiTES RINGENS. Desor, Syuopsis des Echinides Fossiles, p. 207, 1857. 



— — Cotteau and Triger, Echinides du Dcpartement de la Sarthe, 



pi. viii, figs. 5, 6, p. 48. 



— EuDESii. D'Orbigny, Paleontologie Fran^aise Ter. Cretaces, t. vi, p. 49, 



1853. 



— — D'Orbigny, Note rect. sur divers genres d'Echid., Rev. Mag. de 



Zool., 2' serie, t. vii, p. 26, 1854. 



Test sub-orbicular or sub-pentagonal, rounded anteriorly, rostrated posteriorly ; upper 

 surface convex, more or less depressed ; sides tumid ; vertex nearly central ; apices of the 

 ambulacra widely disjoined, posterior pair forming an arch over the anal opening ; vent 

 pyriforra, situated in a sulcus on the posterior margin ; base concave, very much undulated, 

 inter-ambulacra extremely tumid, single posterior area very prominent and much deflected ; 

 mouth-opening small, sub-central, and sub-pentagonal. 



Dimensions. — Height seven tenths of an inch ; antero-posterior diameter one inch and 

 one tenth ; transverse diameter one inch and one twentieth. 



