MYOCONCHA. 115 
1844. Myoconcua cretacea, A. d’Orbigny. Pal. Franc. Terr. Crcét, vol. iii, 
p. 260, pl. ceexxxy. 
? 1847, -- — A. d’Archiac. Mém. Soe. géol. France, ser. 2, 
vol. 11, p. 307. 
1850. — — A. d’Orbigny. Prodr. de Pal., vol. ii, p. 165. 
1854. = —= J. Morris. Cat. Brit. Foss., ed. 2, p. 214. 
1862. -— -- J. G. Chenu. Manuel de Conch., vol. ii, p. 155, 
fig. 766. 
1866. — — F. J. Pictet and G. Campiche. Moll. Foss. Terr 
Crét. Ste. Croix (Matér. Pal. Suisse, ser. 4), 
p. 344. 
? 1868. — — E. Kichwald.  Lethea Rossica, vol. ii, p. 588, 
pl. xxii, fig. 10. 
Description.—Shell subtriangular, or more or less oblong, gradually increasing 
in height posteriorly. Anterior end blunt, rounded ; posterior border rounded, 
somewhat oblique; ventral border nearly straight. Valves flattened, gradually 
compressed posteriorly, more sharply compressed towards the ventral margin. 
Ornamentation consists of slender, equidistant, slightly curving, radial ribs, 
which are absent near the dorsal margin ; the most dorsal rib is stronger than the 
others. The radial ribs are crossed regularly by numerous slender concentric ribs 
which are parallel to the growth-lines. 
Measurements : 
Length. : : : : : ; : . 74mm. 
Height . : ; , : ‘ ; . EOC: 
Thickness . ; : : . : + a2 Saae 
Affinities. —M. Requieniana, Mathéron,' is less expanded posteriorly, and more 
concave ventrally. 
Myoconcha, n. sp., Miller,’ may be an allied form, but is known only by internal 
moulds. 
T'ypes.—From the Cenomanian of Saintes, Angouléme, Rouen, ete. 
Distribution.—Basement bed of Chalk Marl (zone of Schloenbachia variais) of 
Chard, Maiden Newton, and Evershot. Chloritie Marl of Maiden Bradley, Wool- 
combe, and Toller Fratrum.* 
* *Cat. Foss. Bouches-du-Rhone’ (1842), p. 177, pl. xxvii, figs. 3, 4. D’Orbigny, ‘ Prodr. de 
Pal.,’ vol. it (1850), p. 196. 
2 «Die Mollusk. d. Untersen. v. Braunschweig u. Ilsede” (‘ Abhandl. d. k. preuss. geol. Land.,’ 
n. F., pt. 25, 1898), p. 48, pl. vii, fig. 3. 
* Casts of Myoconcha, from the Lower Greensand of Seend, are preserved in the Museum of 
Practical Geology, but the species cannot, at present, be determined. 
