314 



COLLYRITES 



Disaster avellana. 



BICORDATUS. 



Disaster Robinaldinus, 



— SYMMETRICUS. 



— AVELLANA. 



Disaster bicordatus. 



— Agassizii. 



CoLLTfBITES BICORDATA. 



— ANALIS. 



avellana. 



— Agassizii. 



BICORDATA. 

 ANALIS. 

 ANALIS, 

 OVALIS. 



Plaster moulds R 15, R 



Desor, Monograpliie des Disaster, p. 23, pi. 1, fig. 1 — 4, 1842. 

 Agassiz and Desor, Catai. rais. des Echinides, Ann. des Sc. Nat., 



3"" serie, t. vii, p. 32, 1847. 

 Agassiz and Desor, Catal. rais. des Echinides, Ann. des Sc. Nat., 



3""^ serie, t. vii, p. 31. 

 Cotteau, Etudes sur les Echinides Fossiles, p. 73, lab. vii, 



figs. 1—5, 1849. 

 M'Coy, Annals of Natural History, 2d series, vol. ii, p. 415, 



1848. 

 Agassiz, Catal. Syst., p. 3. 

 D'Orbigny, Prodrome de Paleontologie, t. 1, p. 289, No. 43, 



1856. 

 Desor, Monograpliie des Dysaster, p. 23, tab. 1, figs. 1 — 4. 

 M'Coy, Annals of Natural History, 2d series, vol. ii, p. 420, 



1848. 

 Wright, Annals of Natural History, 2d series, vol. ix, p. 210, 



1851. 

 D'Orbigny, Prod, de Pal., t. i, p. 318, No. 399, 1850. 

 Forbes, in Morris's Catalogue of British Fossils, 2d ed., p. 77, 



1854. 

 D'Orbigny, Prod, de Pal., t. i, p. 290, No. 494, 1850. 

 D'Orbigny, Pal. Fran9. Ter. Cretace's, t. vi, p. 49, 1853. 

 D'Orbigny, ibid., p. 48, 1853. 

 D'Orbigny, ibid., p. 48. 

 D'Orbignj', ibid., p. 48. 

 D'Orbigny, Note rect. sur divers genres d'Echinides, Rev. et 



Mag. de ZooL, 2*' serie, t. vi, p. 27, 1854. 

 D'Orbigny, ibid., p. 27. 

 D'Orbigny, ibid., p. 27- 



Desor, Synopsis des Echinides Fossiles, p. 206, 1857. 

 Cotteau, Note sur quelques Oursins de la Sarthe, Bull, de la 



Soc. Geologique de France, 2"*' s^rie, p. 649, 1856. 

 Cotteau et Triger, Echinides du Department de la Sarthe, 



pi. vii, figs. 7 — 9, p. 45, 1857. 

 16, type of bicordatus, Agassiz; Q 82, type of aiialis, X 76, 



type of avellana. 



Test thin, oval, anterior and posterior borders nearly uniform in convexity ; sides 

 tumid ; dorsal surface convex, sometimes flattened ; vertex excentral, situated near the 

 anterior third ; anal opening pyriform, supra-marginal ; postero-lateral ambulacra terminate 

 by the sides or immediately above the anus ; base smooth, convex, without undulations ; 

 mouth-opening small, situated at the junction of the anterior with the middle third. 



Dimensions. — Eight tenths of an inch ; antero-posterior diameter, one inch and one 

 fifth ; transverse diameter, one inch and one tenth. 



