CRASSATELLITES. 129 



but is more inequilateral, the ventral margin is nearly straight, the posterior 

 margin is more oblique, and the posterior area is relatively smaller. It is much 

 more inequilateral than 0. regularis, d'Orbigny. 1 G. divisiensis also resembles 

 some of the varieties of 0. macrodonta (Sowerby) 3 from Gosan. 



Distribution. — Upper Greensand (zone of Schlcenbachia rostrata) of Devizes. 

 An imperfect specimen from Warminster (zone of Peden asjper) probably belongs 

 to this species. 



Crassatellites vindinnknsis (d'Orbigny), 18-14. Plate XIX, figs. 2, 8. 



1844. Crassatella vindinnensis, A. d'Orbigny. Pal. Franc. Terr. Oct., vol. iii, 



p. 79, pi. eclxvi, figs. 1—3. 

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



1867. vindinnensis, E. Gueranger. Album Paleont. de la Sari lie, 



p. 13, pi. xvi, figs. 9, 10. 

 ? 1868. C. W. G Umbel. Geogn. Besclireib. Konigreichs 



Bayern, vol. ii, p. 766. 

 1871. F. Stoliczka. Palseont. Indica, Cret. Fauna S. 



India, vol. iii, p. 294. 



Description. — Shell subquadrate, but trigonal without the posterior area, very 

 inequilateral, convex, with rounded carina. Anterior margin rounded, passing 

 gradually into the slightly curved ventral margin ; posterior margin oblique, some- 

 what sinuous ; postero-dorsal margin nearly straight, forming an obtuse angle with 

 the posterior margin. Lunule elongate, deep. Umbones prominent, incurved. 

 Posterior area of moderate size, divided by a median rib into two parts, of which 

 the anterior is concave. 



Ornamentation consists of strong, regular, concentric ribs, separated by narrow 

 furrows. On the posterior area the ribs become very narrow and more or less 

 lamellar, and the interspaces are broad and flat. 



Measurements : 



(1) (2) 



Length 31 30 nun. 



Height 26 . . 26 „ 



(1, 2) Dunscombe. 

 Affinities. — This species is related to G. ligeriensis, d'Orbigny, 3 and G. Gueran- 



1 Op. cit., p. 80, pi. eclxvi, figs. 4 — 7. 



2 Zittel, "Bivalv. d. Gosaugeb." (' Denlcschr. d. k. Akad. Wien, Math. -Nat, CI.,' vol. xxv, pt. 2, 

 1866), p. 150, pi. viii, figs. 2, 3. 



3 'Pal. Franc. Terr. Cret.,' vol. iii (1844), p. 77, pi. eclxv, figs. 3— 5 ; Gucranger, ' Allium Paleont. 

 de la Sarthe' (1867), p. 13, pi. xvi, fig. 12. 



17 



