218 CRETACEOUS LAMELLIBRANCHIA. 
T'ype.—From Atherfield, in the Museum of the Geological Society. 
Distribution.—Lower Greensand (Crackers) of Atherfield, Atherfield Beds of 
Kast Shalford and Sevenoaks. Sandgate Beds of Parham Park. 
Genus—Sorecurtus, I. M. D. de Blainville, 1824. 
(‘ Dict. Sei. nat:,’ vol. xxxai, p. 351.) 
Sub-genus—Azor, W. H. Leach, 1847. 
(In Gray, ‘ Ann. Mag. Nat. Hist.,’ vol. xx, p. 272; and ‘ Proc. Zool. Soc.,’ 1847, p. 189.) 
Sorzcurtus (Azor?) Petact, d’ Orbigny, 1850. Plate XXXYV, fig. 4. 
1850. Sonecurtus Pexaat, A. d’Orbigny. Prodr. de Pal., vol. 11, p. 158. 
1867. — — E. Guéranger. Album Paléont. de la Sarthe, p. 12, 
pl. xv, fig. 6. 
1870. — — F. Stoliczka. Paleont. Indica, Cret. Fauna 8. India, 
vol. ii, p. 99. 
Description.—Shell elongate, considerably inequilateral, moderately convex, but 
shghtly concave at the middle of the sides. Postero-dorsal area flattened or shghtly 
concave, limited by an indistinct carina. Antero-dorsal margin curved; anterior 
margin rounded; postero-dorsal margin straight, nearly parallel to the ventral 
margin; posterior margin curved, slightly oblique. Ornamentation consists of 
small concentric ribs near the umbo, and of growth-rings elsewhere. Length 30: 
mm.; height 12 mm. 
Affinities —The identification of the English specimens with d’Orbigny’s species 
is not quite free from doubt, since only two valves, both somewhat imperfect, have 
yet been seen. In the specimen figured by Guéranger the postero-dorsal area 
seems relatively higher than in our specimens; also the postero-dorsal margin is 
less nearly straight, but this difference may be due to imperfect preservation. 
S. Pelagi seems to be closely allied to S. Guerangeri, dOrbigny,’ but the 
carina is less distinct, and the postero-ventral angle appears to be more rounded. 
Until specimens showing the hinge satisfactorily have been found, the generic 
position of this species must be regarded as doubtful. 
Type.—From the Cenomanian of Le Mans. 
Distribution.—Upper Greensand (zone of Schlanbachia rostrata) of Blackdown. 
1 «Pal. Frang. Terr. Crét.,’ vol. iii (1845), p. 321, pl. eccli, figs. 1, 2. Gudranger, ‘ Album 
Paléont. de la Sarthe’ (1867), p. 12, pl. xv, fig. 4. An internal cast of a left valve from the Upper 
Greensand of Warminster resembles S. Guerangeri. 
