10 MOLLUSCA FROM THE CRAG. 



of its characters, hwt may be distinguished, if not specifically, certainly as a variety, 

 by its sculpture, which is in the form of spinous or squamose radiations. In the 

 recent state, the lower or perforated valve, is said to be generally thin and fragile, and 

 destitute of the aculeated striae. As the shells found in the Crag are separated or 

 detached, they would not be recognised, if this were always the case ; but many of the 

 lower valves are alike ornamented with these markings, though they arc less con- 

 spicuously so than upon the upper ones. The umbo of this is placed very near the 

 margin, and is generally slightly recurved ; the striae are numerous, although in 

 some specimens they are more distant ; but in all they have more or less, the 

 vaulted or raised, and slightly reflected edges, which as it grows produce the 

 series of aculeated or fimbriated striae upon the exterior, though very faintly 

 exhibited in the variety called sfriolata. In the very young of some of my speci- 

 mens, the shell appears to be free from sculpture of any kind, and this may favour the 

 opinion of Mr. Clark. 



3. Anomia p.\telliformis, Linnmis. Tab. I, fig. 4, a — b. 



Anomia patelliformis. Linn. Nov. Act. Upsal., vol. i, p. -42, pi. :>, figs. C, 7, 1773. 



— — Loi-en. lud. Moll. Scandin., p. 30, 1846. 



— — Alder. Cat. Moll. North, and Durli., p. 75, 18-18. 



— — Forf). and Hani. Hist, of Brit. Moll., vol. ii, p. 334, pi. .56, 



figs. .■), 6, 1S4!). 



— — Middendorff. Malac. Ross. (Mem. de I'.Vcad. des Sc. St. Pctersb.), 



p. 521, 18-19. 



— UNDCLATIM STRIATA. Chem. Conch. Cab., t. viii, p. 88, tab. 77, fig. 699. 



— UNDULATA. Gtnel. Syst. Nat., p. 33, 46. 



— — Mont. Test. Brit., p. 157, pi. 4, fig. 6, 1803. 



— — Turt. Brit. Biv., p. 230, pi. 18, figs. 8, 9, 10, 1822. 



— — Drown. Illust. Concb. Gr. Brit., pi. 34, figs. 2, 3, 1827. 



— — Flem. Brit. An., p. 39."), 1828. 



— — S. Wood. Catalogue, 1840. 



OsTREiM STRIATUM. Dacosta. Brit. CoHch., p. 162, pi. 11, fig. 4. 

 OsTREA STRIATA. Donov. Brit. Shells, vol. ii, tab. 45, 1801. 



— — Mont. Test. Brit., pp. 1.53, 580, 1803. 



— — List. Hist. Conch., fig. 36. 



Ency. Meth., pi. 171, fig. 16, and pi. 184, figs. 5, 6. 



Spec. Char. Testa subordicidari, plicis 20 — 30 coiwexis, unchilati-racUatis ; striis 

 concentricis crebris, sublariiiiiaceis ; vmbonc subprominulo a marline remofiitsciilo. 



Shell suborbicular, ornamented with 20 — 30 radiating and undulating ribs ; con- 

 centric striae or lines of growth thick and sublaminated ; umbo slightly prominent, 

 a little distant from the margin. 

 Diameter, \\ inch. 

 Locality. Cor. Crag, Sudbourn and Sutton. 



Red Crag, Sutton, Bawdsey, Walton Naze. 



Recent, Britain and Scandinavia. 



