BEITISH FOSSILS. 



Decade III. Plate X. 



MICRASTER COR-ANGUINUM. 



[Genus MICRASTER. Agassiz. (Sub-kingdom Radiata. Class Echinodermata. Order 

 Echinidse. Family Spatangacese.) Body cordate, tumid; dorsal ambulacra narrowly 

 petaloid, not circumscribed by a peripetal band ; dorsal surface studded with uniform small 

 tubercles, no large primaries ; anus terminal, supra-marginal ; caudal (infra-anal) ex- 

 tremity circumscribed by a band.] 



Diagnosis. M. ambitu cordato, dorso convexo, postice arcuato ; am- 

 bulacris dorsalibus impressis, sulcis porarum terminalium vix decrescentibus ; 

 assulis arearum ambulacralium dorsalium tumidis, subtuberculatis. 



Forma oc. Normalis, regulariter cordatus^ dorso vertice suhcentrali ; 

 genis tumidis. Spatangus cor-anguinum a. anglicum, Leske, ap. Klein, 

 p. 28, tab. 23, A, B. Echinus cor-anguinum^ Gmelin, 3195. Spatangus 

 cor-anguinum and punctatus. Ananchytes spatangus and semiglobosus, La- 

 marck, An. sans Vert, iii., pp. 26 and 32. Spatangus cor-anguinum, 

 Alex. Brongniart, Desc. Geol. des Env. de Paris, pi. 4, fig. 11. Spa- 

 tangus cor-marinum, Parkinson, Org. Eem. iii., pi. 3, fig. 11. Spatangus 

 cor-anguinum, Goldfuss, Pet. Germ., pi. 48, fig. 6; and Spatangus cor- 

 testudinarium, ibid., pi. 48, fig. 5. Micr aster cor-anguinum, Agassiz and 

 Desor, Cat. Rais., in Ann. des Sc. Nat., 3rd series, tome viii., p. 23. 

 Micraster cor-testudinarium, Bronn, Lethsea, pi. 29, fig. 23. 



Forma /S. Hostratus, regulariter cordatus, dorso cari?iato, vertice in 

 area anali, genis tumidis. Ananchytes cor data, Lamarck, An. sans 

 Vert. iii. Spatangus rostratus, Mantell, Geol. Suss., pi. 17, figs. 10, 

 12 ; Woodward, Geol. Norf., pi. 5, fig. 7. Micraster cordatus, Agassiz, 

 Cat. Syst., 2 ; and Cat. Rais. des Ech., p. 23. 



Forma y. Gibbus, late cordatus, dorso vertice centralis postice an- 

 ticeque declivente, genis compressis. 



Var. a. pyramidata. Spatangus gibbus, Lamarck, Aiiim. sans Vert, iii., 

 fig. in Ench. Meth., pi. 156, figs. 4-6. Micraster gibbus, Agassiz and 

 Desor, Cat. Rais. des Echin. Ann. des Sc. Nat., 3rd ser., tome viii., p. 24 ; 

 Forbes, in Dixon's Sussex, p. 342, pi. 24, fig. 314. 



[ill. X.] B 



