98 CRETACEOUS LAMELLIBRANCHIA. 
1865. Myrinus sussimpLex, H. Coquand. Mon. Aptien de | Espagne, p. 145. 
1867. — -- F. J. Pictet and G. Campiche. Foss. Terr. Crét. 
Ste. Croix (Mat¢r. Pal. Suisse, ser. 4), pp. 493, 507. 
1882. Moptona sus-simpLex, P. de Loriol. Gault de Cosne (Mém. Soc. Pal. 
Suisse, vol. ix), p. 81, pl. ix, fig. 17. 
1884. Myrrius stmpiex, O. Weerth. Die Fauna d. Neoc. im Teutoburg. Walde 
(Paleont. Abhandl., vol. 11), p. 47. 
1895. — — G. Maas. Zeitschr. der deutsch. geol. Gesellsch., vol. 
xlvii, p. 266. 
1896. Moprona stmpLex, A. Wollemann. Zeitschr. der deutsch. geol. Gesellsch., 
vol. xlvii, p. 844. 
1897. Mytinus — R. B. Newton. Proce. Dorset Nat. Hist. and Antiq. 
Field Club, vol. xviii, p. 89, pl. in, fig. 13. 
1900. Moproua susstmpLex, A. Wollemann. Die Biv. u. Gastrop. d. deutsch. u. 
holland. Neocoms. (Abhandl. d. k. preussisch. geol 
Land., N. F., pt. 31), p. 62.3 
Description.—Shell elongate, straight 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 ; i front 
of this is a shallow depression. Surface smooth except for faint growth-lines. 
Measurements : 
(1) (2) (3) (4) ( 
Length (greatest). Ol 6 SASS es Ade 340% 8 0Gmm. 
Height (at right angles to 
greatest length) 3 pe Oe ho oo al eel mle 
Thickness : ‘ : ete ee CD25 ee) a OO Spee ore 
(1)—(5) all from the Crackers of Atherfield. 
Affinities —This species is very near to, and perhaps identical with, M. siliqua, 
Mathéron ;’ but the latter is said to have the anterior extremity more obtuse. 
M. semiornatus, @Orbigny, has the concentric ornament more pronounced on 
the dorsal part of the shell. 
M. rectior, Wollemann,’ from the Hails-conglomerate of Brunswick, is very 
' «Catal. Foss. Bouches-du-Rhone’ (1842), p. 178, pl. xxviii, figs. 5, 6; d’Orbigny, ‘Pal. Frane. 
Terr. Crét.,’ vol. iii (1844), p. 274, pl. cccexxxix, figs. 3, 4; and ‘Prodr. de Pal.’ (1850), p. 165; 
Geinitz, ‘Quadersandst. in Deutschland’ (1850), p. 168, pl. x, fig. 14; Zittel, ‘Die Bivalv. der 
Gosaugeb.,’ pt. 2 (1866), p. 81 (p. 5 reprint), pl. xi, fig. 3; Pictet and Campiche, ‘ Foss. Terr. Crét. 
Ste. Croix (1867), p. 510; Geinitz, ‘Das Elbthalgeb. in Sachsen,’ pt. 1 (1873), p. 215, pl. xlvii, fig. 3, 
pt. 2, pl. xv, fig. 4; Bohm, “ Kreidebild. Fiirbergs,” etc. (‘Paleontographica,’ vol. xxxviii, 1891), 
p. 81, pl. iu, fig. 29; Miller, “ Mollusk. Untersen, Braunschweig und Isede ” (‘ Abhandl. d. k. preuss. 
geol. Land.,’ N. F., pt. 25, 1898), p. 46, pl. v, fig. 14. 
* *Zeitschr, d. deutsch, geol, Gesellsch.,’ vol. xlviii (1896), p. 844, pl. xxi, f. 6; and ‘Die Biv. u. 
Gastrop. d. deutsch. u. hollind. Neoc,’ (1900), p. 63. 
