1.52 



CONCHIFERA. 



DiANI 



Somewhat gibbose, obliquely sub-ovate ; anterior side a 

 little flattened below the beaks, ears unequal, beaks produced ; 

 surface smooth, with numerous fine divergent ribs, and a few 

 concentric distinct lines of growth. 



The Kelloways Rock, Kelloways. 



13. Plagiostojia pectinoides. — The Pectinated Plagios- 

 toma, pi. LXVI. fig. 9. 



P. pectinoides. Sowerby, II. p. 28, pi. 114, fig. 2. 



Oblong-ovate, considerably oblique, compressed, back some- 

 what angular ; beaks acute ; hinge-line long, ears nearly equal, 

 and rather large ; both sides a little straight, the anterior one 

 considerably exceeding the posterior ; surface with twenty or 

 more carinated, slightly divergent ribs, and the intervening 

 furrows transversely striated ; margin scolloped ; inside, plane. 



The Lias, Pickeridge, Yorkshire. 



14. Plagiostoma cabdiiforme. — The Cardium-shaped 

 Plagiostoma, pi. LXYI. fig. 14. 



P.cardiiformes. Sowerby, II. p. 26, pi. 113, fig. 3. 



Nearly circular, inflated ; anterior side short and straight ; 

 ears equal ; beaks prominent ; surface smooth, with numerous 

 longitudinal divergent furrows, crossed by nearly obsolete 

 transverse strice, which are hardly visible but in the furrows, 

 where they have the appearance of minute punctures. 



The Oxford Clay, Cambridge, Kelloways Rock, Glouces- 

 tershire, and the Inferior Oolite, Cotswold. 



15. Plagiostoma Brightonense. — The Brighton Plagios- 

 toma, pi. LXI.** fig. 26. 



P. Brightonenses. Mantell, Geo. Sussex, p. 204, pi. 25, 

 fig. 15. 



Obovate, compressed, posterior side with an ear ; anterior 

 side concave, lunulate, small and acuminated ; surface with 

 numerous divergent rounded ribs ; the margin crenulated. 



The Upper Chalk, Brighton. 



16. Plagiostoma asperum. — The Rough Plagiostoma, 

 pi. LXI.*fig. 11. 



P. asjxra. Mantell, p. 129, pi. 26, fig. 18. 



Obovate, sub-compressed, with numerous flat ribs, the edges 

 of which are fringed with minute sharp prickles ; lines of 

 growth few. 



The Gray Chalk Marl, Hamsey, Sussex. 



17. Plagiostoma I^•TERSTI^•CTUM. — The Divided Plagios- 

 toma, pi. LXVI. fig. 11. 



P. interstinctum. Phillips, Geo. York, I. pi. 7, fig. 14. 



Obliquely obovate, sides straight about half way below the 

 hinge ; beaks produced ; ears indistinct ; surface with many 

 sharp, somewhat irregular divergent ribs ; margin crenated. 



The Great Oolite, Whitwell, Yorkshire. 



18. Plagiostoma rigidulum. — The Rigid Plagiostoma, 

 pi. LXVI. fig. 7. 



P. rigidulum. Phillips, Geo. York, pi. 7, fig. 13. 



Elongated, sub-triangular, considerably oblique ; anterior 

 side elongated and concave ; posterior side short and rounded ; 

 ears unequal ; that of the posterior side very small, anterior 

 one extending a considerable way down the side ; beak large 

 and obtuse ; surface smooth, with many oblique divergent 

 rounded ribs. 



The Cornbrash, Scarborough. 



19. Plagiostoma obliquatum. — The Oblique Plagiostoma. 



P. olliquatum. Sowerby, Geo.Tr. 2d Ser. II. p. 319. 

 The Portland Stone, Thame and Brora. 



20. Plagiostoma Hermani ? — Herman's Plagiostoma, 

 pi. LXVI. fig. 12. 



Plagiostoma Hennani. Phillips, Geo. York, I. pi. 14, fig. 18. 



Sub-rotund, slightly oblique ; anterior side straight, and a 

 little concave below the beaks ; posterior side shorter than the 

 other ; ears unequal, of medium size ; beaks slightly produced, 

 surface smooth, with about 15 very flat longitudinal ribs, and 

 a few remote lines of growth. 



In the Marlestone and Calcareous Nodules, Upper Lias, 

 Yorkshire. 



21. Plagiostoma ambiguum. — The Ambiguous Plagios- 

 toma, pi. LXVI. fig. 8. 



Plagiostoma. Phillips, Geo. York, pi. 6, fig. 23. 



Sub-triangular, sides nearly equal, hinge-line short, slightly 

 oblique; beaks acute and produced; surface with about twenty- 

 three rounded divergent ribs, crossed by a few distant lines of 

 growth ; margins scolloped. 



The Mountain Limestone, Yorkshire. 



22. Plagiostoma Mantelh(?) — Mantell's Plagiostoma, pi. 

 LXL* fig. 41. 



P. Mantelli. Goldfuss, II. pi. 104, fig. 9. 



Obliquely semicircular ; right side truncated; surface with 

 radiating strije, and a few concentric ones, which become ob- 

 solete on the back ; the lunule hollow and lineated. 



The Upper Greensand, Lyme Regis. 



23. Plagiostoma dubium. — The Doubtful Plagiostoma, 

 pi. LXVI. fig. 16. 



Plagiostoma (?) Phillips, Geo. York, I. pi. V. 10. 



Obliquely ovate, anterior side nearly straight ; posterior 

 side rounded ; beaks obtuse ; surface with numerous flat, diver- 

 gent ribs, which are obsolete towards the apex ; with a few 

 remote linos of growth. 



The Oxford Clay, Yorkshire. 



GEyvsXKI.—DlANCllOllA.—Sowerb]/. 



Shell ineqnivalve, sub-triangular, oblique, adherent ; attach- 

 ed valve provided with an angular hiatus instead of an umbo ; 

 the other valve auriculated, and with an obtuse umbo ; hinge 

 destitute of teeth. 



1. DiANcnoRA striata. — The Striated Dianchora, pi. 

 LXVI." figs. 1, 2. 



B. striata. Sowerby, I. p. 183, pi. 80, fig. 1. 



Triangularly-ovate, oblique, length and breadth nearly equal ; 

 beak prominent ; free valve obscurely ribbed ; ears small, and 

 continuous along the sides of the valves. 



Greensand, near Warminster, Dane's Dyke, Wiltshire and 

 Blackdown. 



2. Dianchora lata. — The Broad Dianchora, pi. LXVI.*, 

 fig. 3. 



£). lata. Sowerby, I. p. 184, pi. 80, fig. 2. 



The attached convexity moderate ; semicircular ; beak of 

 valve produced ; free valve plain ; surface with obscure lines 

 of growth, and provided with a few obsolete striae ; edge very 

 sharp. 



Chalk, near Lewes, Sussex. 



