118 CRETACEOUS LAMELLIBRANCHIA. 



outline, and apparently also fewer ribs. Two imperfect specimens from the 

 Cenomanian (Bed 11) of Dunscombe were referred to A. Konincki by the late 

 C. J. A. Meyer, but they are less convex than that species and seem to agree 

 more nearly with A. striata. 



Astarte concinna, Sowerby, was regarded by Stoliczka as probably identical with 

 A. striata. It is known by the type specimen only, and agrees with A. striata, 

 except that it is rather higher and more inequilateral. I believe that it is merely 

 an individual variation of A. striata. 



Types. — From Blackdown, in the British Museum. The type of A. concinna is 

 from Blackdown and is now in the Bristol Museum. 



Distribution. — Upper Greensand (zone of ScMambachia vostrata) of Blackdown. 



Genus— Opis, M. J. L. Defiance, 1825. 



(' Diet. Sci. nat.' vol. xxxvi, p. 219.) 



Oris neocomiensis, d'Orbigny, 1844. Plate XVII, figs. 8-12. 



1842. Opis A. Leymerie. Mem. Soc. geol. de France, ser. 2, vol. v, 



p. 25, pi. vii, fig. 4. 

 1844. — neocomiensis, A. d'Orbigny. Pal. Franc. Terr. Oct., vol. iii, p. 51, 



pi. ecliii, figs. 1 — 5. 

 1850. — d'Orbigny. Prodr. de Pal., vol. ii, p. 76. 



1855. — G. Cotteau. Moll. Foss. de l'Yonne, p. 67. 



1857. — F. J. Pictet and E. Renevier. Foss. Terr. Aptien (Mater. 



Pal. Suisse, ser. 1), p. 

 83, pi. ix, fig. 7. 

 1861. — Desori, P. de Loriol. Anim. Invert. Foss. Mt. Saleve, p. 66, pi. viii, 



figs. 4—7. 

 1866. — neocomiensis, F. J. Pictet and G. Campiche. Foss. Terr. Oct. Ste. 



Croix (Mater. Pal. Suisse, ser. 4), 

 p. 324, pi. exxv, figs. 3, 4. 

 1868. — — P. de Loriol. Valangien d'Arzier, p. 31. 



v 1871. — — W. A. Ooster. Protozoe Helvet., vol. ii, p. 101, pi. xv, 



fig. 17. 

 1883. — — W. Keeping. Foss. etc., Neoc. Upware and Brickliill, 



p. 121, pi. vi, fig. 8. 

 1900. A. Wollemann. Die Biv. u. Gastrop. d. deutsch. u. 



holliind. Neocoms (Abhandl. d. k. 

 preussisch. geol. Land., N. F., pt. 

 31), p. 102. 



Description. — Shell trigonal or sub-quadrilateral, much higher than long, 

 inequilateral, greatly inflated, but with flattened sides. Anterior margin rounded. 



