62 MOLLUSCA FROM THE CRAG. 
6. MoproLA MARMORATA, Forbes. Tab. VIII, fig. 7. 
Myrrtus piscors. Da Costa. Brit. Conch., p. 221, t. 17, fig. 1, 1778. 
= -- Walker and Boys. Test. Min. Rar., pl. 3, fig. 79, 1789. 
— — Poli. Test. Utr. Sie., vol. ii, p. 211, pl. 32, figs. 15, 16, 1795. 
— — Donov. Brit. Shells, vol. i, pl. 25, fig. 1, 1799. 
— — Mat. and Rock. Linn. Trans., vol. viii, p. 111, pl. 3, fig. 8, 1807. 
— — Mawe. Conch., pl. 13, fig. 5, 1823. 
— — W. Wood. Ind. Test., pl. 12, fig. 39, 1825. 
Mopiota = — Turt. Brit. Biv., p. 201, pl. 15, fig. 4, 1822. 
— — Brown. Mlust. Brit. Conch., pl. 29, fig. 10, 1827. 
—_ — S. Wood. Catalogue, 1840. 
— — ? Gould. Inv. Massach., p. 15, fig. 84, 1841. 
— DISCREPANS. PAil. En. Moll. Sic., vol. i, p. 70, 1836. 
— — Uf fale - - vol. ui, p. 50, pl. 15, fig. 11, 1844. 
—_ — Payr. Cat. Moll. Cors., p. 67, 1826. 
— Evropma. D’Ord. fide Lovén. 
— tumipa. Hanley. Rec. Shells, vol. i, p. 241, pl. 12, fig. 39. 
— MARMORATA. Fordbes. Malac. Monen., p. 44, 1838. 
— — Brown. Mlust. Brit. Conch., 2d ed., pl. 27, fig. 10. 
— — Alder. Cat. Moll. North. and Durh., p. 82, 1848. 
MoproLtarIa — Lovén. Ind. Moll. Scand., p. 33, 1846. 
CRENELLA — Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 198, pl. 45, fig. 4, 1849. 
Spec. Char. Testé minutd, ovato-ellipticd, tumidd, tenm, fragili; utroque latere 
striata, spatio submediano levigato vel transverse striato; umbonibus minimis subter- 
minalibus. 
Shell small, ovate or elliptical, tumid, thin, and fragile; both sides radiatingly 
striated, with a smooth or rather transversely striated space between them ; umbones 
small, subterminal. 
Longest diameter, 3ths of an inch. 
Locality. Cor. Crag, Sutton. 
Red Crag, Walton Naze. 
Recent, Mediterranean, Britain, Scandinavia, and North America? 
Small specimens and fragments of this species are abundant in the Coralline 
Crag at Sutton, and it appears to have been one of the commoner shells of that 
Period. There is no doubt, of this shell being identical with the recent British 
species, now determined not to be the dscors of Linnzus, a name given to a larger 
shell (Mytulus impactus, Herm.) by the Swedish naturalist. 
Our shell in the fossil state has become opaque, but it has retained its nacreous 
appearance ; it is of an elliptical form, the anterior side being rather broader than the 
posterior, which is slightly narrowed off from the dorsal slope ; the umbones are small, 
slightly inflected, with the anterior side projecting a little beyond them, the shell is 
somewhat regularly tumid, with a very slight flattening on the dorsal portion: the 
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