210 CRETACEOUS LAMELLIBRANCHIA. 



Type. — From Norwich ; in the British Museum. 



Distribution. — Upper Chalk (zone of Belemnitella mucronata) of Norwich. 



GtYROPlbura, sp. Plate XXXIV, fig. 1 a — d. 



Description. — Right valve inflated, attached by a large portion of the dorsal 

 surface. Left valve convex, subquadrate, with a pointed and incurved umbo. 

 Right valve ornamented with numerous, small radial ribs which bear transverse 

 nodes or scales. Left valve with relatively few, stout ribs bearing strong, some- 

 what irregular, transverse scales or lappet-like projections. 



Affinities. — The ornamentation on the right valve is finer and that on the left 

 valve coarser than in G. cenomanensis (d'Orbigny 1 ) ; also the transverse ornamenta- 

 tion of the ribs is much coarser and less regular. 2 



Remarks. — The portion of the right valve which was attached includes the 

 umbo and the neighbouring parts, whereas in most examples of Gyropleura only 

 the part in front of the umbo is attached. The size of the area which was attached 

 is larger than usual, but in other species it is seen that that area varies considerably 

 in size in different examples. 3 



The only specimen seen was collected by Mr. Francis R. B. Williams. 



Distribution.-— JJ^per Chalk (zone of Actinoeamax quad/ratus) near the groyne 

 at Seaford. 



Family— CORBULID^E, Fleming. 



Genus — Corbula, J. G. Bruguiere, 1797. 

 ('Encyc. Meth.,' Tabl. Vera., pi. 230.) 



Corbula anoulata (Phillips), 1829. Plate XXXIV, figs. 2—5. 



1829. Isocardia angdlata, J. Phillips. Greol. Yorks., p. 94, pi. ii, figs. 20, 21 



(ed. 3, 1875, p. 252). 

 1841. — — F. A. Romer. Die Verstein. d. nord - deutsch. 



Kreidegeb., p. 70. 

 1854. — J. Morris. Cat. Brit. Foss., ed. 2, p. 204. 



1 ' Pal. Fran?. Terr. Oct.,' vol. iv (1850), p. 261, pi. dxcv, figs. 1—4. 



2 Douvilk', 'Bull. Soc. geol. de France,' ser. 3, vol. xv (1887), p. 771, pi. xxviii, fig. 7. 



:! In a specimen figured by Griepenkerl the surface of attachment is unusually large ; ' Senon v. 

 Konigslutter ' ('Pakeont. Abhandl.,' v, 1889), pi. vii, fig. 3. 



