t)8 CRETACEOUS LAMELLIBRANCHIA. 



1865. Mttilus subsimplex, H. Coquand. Mou. Aptieu de I'Espague, p. 143. 

 1867. — — F. J. Pictet and G. Campiche. Foss. Terr. Cret. 



Ste. Croix (Mater. Pal. Suisse, ser. 4), pp. 493, 507. 

 1882. MoDioLA sxjB-siMPLEX, P. dc Loriol. Gault de Cosne (Mem. Soc. Pal- 



Suisse, vol. ix), p. 81, pi. ix, fig. 17. 

 1884. Mytilus simplex, 0. Wccrth. Die Fauua d. Neoc. im Teutoburg. Walde 



(Palseont. Abhandl., vol. ii), p. 47. 



1895. — — G. Maas. Zeitschr. der deutscli. geol. Gesellscli., vol. 



xlvii, p. 266. 



1896. MoDiOLA SIMPLEX, A. Wollemann. Zeitschr. der deutsch. geol. Gesellscli., 



vol. xlviii, p. 844. 



1897. Mytilus — B. B. Newton. Proc. Dorset Nat. Hist, and Antiq. 



Field Club, vol. xviii, p. 89, pi. iii, fig. 13. 

 1900. MoDiOLA SUBSIMPLEX, A. Wollemann. Die Biv. u. Gastrop. d. deutsch. u. 



holljiud. Neocoms. (Abhandl. d. k. preussisch. geol 

 Land., N. F., pt. 31), p. 62.] 



Description. — Shell elongate, straiglit or curved, somewhat compressed. Ante- 

 rior extremity narrow ; posterior part somewhat expanded. Hinge-margin straight, 

 long ; posterior margin relatively short, curved, oblique ; ventral margin concave. 

 A rounded ridge extends from the umbo to the postero-ventral extremity ; in front 

 of this is a shallow depression. Surface smooth except for faint growth-lines. 



Measurements : 



Length (greatest) 



Height (at right angles to 



greatest length) 

 Thickness .... 



(Ij— (5j all from the Crackers of Atherfield. 



Ajfinities. — This species is very near to, and perhaps identical with, M. silirpia, 

 Matheron ; ^ but the latter is said to have the anterior extremity more obtuse. 



M. semiornatus, d'Orbigny, has the concentric ornament more pronounced on 

 the dorsal part of the shell. 



M. redior, Wollemaim,~ from the Hils-conglomerate of Brunswick, is very 



1 'Catal. Foss. Bouclies-du-Rhune ' (1842), p. 178, pi. xxviii, figs. 5, 6; d'Orbigny, 'Pal. Fran^. 

 Terr. Cret.,' vol. iii (1844), p. 274, pi. cccxxxix, figs. 3, 4; and ' Prodr. de Pal.' (1850), p. 165; 

 Geinitz, ' Quadersandst. in Deutschlaud ' (1850), p. 168, pi. x, fig. 14; Zittel, 'Die Bivalv. der 

 Gosaugeb.,' pt. 2 (1866), p. 81 (p. 5 reprint), pi. xi, fig. 3; Pictet and Campiche, ' Foss. Terr. Cret. 

 Ste. Croix (1867), p. 510; Geinitz, 'Das Elbthalgeb. in Sachsen,' pt. 1 (1873), p. 215, pi. xlvii, fig. 3, 

 pt. 2, pi. XV, fig. 4; Bohm, " Kreidebild. Fiirbergs," etc. (' Palaeontographica,' vol. xxxviii, 1891), 

 p. 81, pi. iii, fig. 29 ; Miiller, " Mollusk. Untersen. Braunschweig und Ilsede " (' Abhandl. d. k. preuss. 

 geol. Land.,' N. F., pt. 25, 1898), p. 46, pi. v, fig. 14. 



" 'Zeitschr. d. deutsch, geol. Gesellscli.,' vol. xlviii (1896), p. 844, pi. xxi, f. 6; and 'Die Biv. u. 

 Gastrop. d. deutsch. u. holltind. Neoc' (1900), p. 63. 



(1) 



51 , 



(2) 



, 48 



(3) 



. 44 , 



(4) 



. 34 . 



(5) 



30 mm. 



16 



. 15 



. 14 , 



. 18 . 



n » 



— 



. 12-5 



. 11 



. 10 , 



7"5 „ 



