216 CRETACEOUS LAMELLIBRANCHIA. 



Corbula elegans, Sowerby, 1827. Plate XXXIV, figs. 23 — 28. 



1827. Corbula elegans, /. de C. Sowerby. Min. Couch., vol. vi, p. 139, pi. dlxxii, 



fig. 1. 

 1850. A. d'Orbigny. Prodr. de Pal., vol. ii, p. 160. 



1854. /. Morris. Cat. Brit. Foss., ed. 2, p. 195. 



? 1867. ?, E. Gueranger. Album Paleout. de la Sarthe, p. 12, 



pi. xvi, fig. 1. 

 1870. F. StoliczTca. Palaeont. Iudica, Cret. Fauna S. India, 



vol. iii, p. 40. 



Non 1846. A. d'Orbigny. Pal. Franc. Terr. Cret., vol. iii, p. 460, 



pi. ccclxxxviii, figs. 14 — 17 (C. elegantula, d'Orbigny, 

 1850). 



? — 1847. ?, A. cVArchiac. Mem. Soc. geol. de France, ser. 2, 



vol. ii, p. 302. 



Description. — Shell subtrigonal, rounded, very convex, inequivalve, inequi- 

 lateral, a little longer than high. 



Right valve with the anterior part sloping rapidly to the margin ; anterior 

 margin rounded ; ventral margin convex, its posterior part curving upwards. 

 Posterior part produced, compressed, separated from the sides by a groove passing 

 from the umbo to the postero-ventral angle ; on the dorsal side of the groove is a 

 small carina. Posterior margin truncated, forming approximately a right angle 

 with the straight postero-dorsal margin. Umbo prominent, sharp, curved con- 

 siderably inward and somewhat forward. Ornamentation consists of strong, 

 broad, concentric ribs separated by narrow grooves, except on the postero-dorsal 

 area, which is nearly smooth. 



Left valve smaller, less convex, and with smaller ribs than the right valve. 

 Postero-dorsal area separated from the side of the valve by a groove or sharp 

 carina. 



Measurements : 



Length 

 Height 



(1—4) Blackdovvn. 



Affinities. — This species is distinguished from G. elegantula, d'Orbigny, by its 

 broader concentric ribs and rostrate posterior end. It is less globose, less pointed 

 posteriorly, and has stronger ribs than C. substriatula, d'Orbigny. 



Type. — From Blackdown, in the British Museum. 



Distribution. — Upper Greensand (zone of Schlmnbacliia rostra ta) of Blackdown 

 and Hal don. Recorded by Price from the Upper and Lower Grault of 

 Folkestone. 



(1) 



(2) 



(3) 



(4) 



6 



5-5 



5 



4*5 mm 



475 



4-5 



4 



3-6 „ 



