BIVALVIA. 27 



P. Groenlandicus, Loven and G. B. Sow., Thes. Conch., p. 57, PL 13, fig. 40, 

 appears to differ from our shell only in being somewhat larger. 



4. PECTEN TIGRINUS, Mutter. Tab. V, fig. 2, ag. 



PECTEN TIGRINUS. Mull. Zool. Dan., ii, p. 26, pi. 60, figs. 68, 1776. 

 Desk. 2d ed. Lam., t. viii. p. 155, 1835. 

 Nyst. Coq. Foss. de Beige, p. 303, pi. 23, figs. 410, 1844. 

 Lov6n. Ind. Moll. Scand., p. 31, 1846. 

 Alder. Cat. of Moll. North, and Durh., p. 77, 1847. 

 Forb. and Hani. Hist, of Brit. Moll., vol. ii, p. 285, pi. 50, figs. 811. 

 OBSOLETUS. Penn. Brit. Zool., vol. iv, p. 322, t. 64, fig. 3. 

 Don. Brit. Shells, vol. i, t. i, fig. 2, 1799. 

 Mont. Test. Brit., p. 149, and sup., p. 57, 1808. 

 Turt. Brit. Biv., p. 213, pi. 9, fig. 6, 1822. 

 Brown. Illust. Conch. Gr. Brit., pi. 33, fig. 6, 1827. 

 J.Sowerby. Min. Conch, t. 541, figs. 18, 1828. 

 Nyst. Rech. Coq. Foss. d'Anv., p. 19, No. 74, 1835. 

 S. Wood. Catalogue, 1840. 

 J. Morris. Cat. of Brit. Foss., p. 115, 1843. 

 Thorpe. Brit. Mar. Conch., p. 118, 1844. 

 PARVUS. Da Costa. Brit. Conch., p. 155, 1778. 

 L^VIS. Penn. Brit. Zool., vol. iv, p. 102. 



Mont. Test. Brit., pp. 150, 579, pi. 4, fig. 1, 1803. 

 Turt. Brit. Biv., p. 212, 1822. 

 Brown. Illust. Conch. Gr. Brit., pi. 33, fig. 7, 1827. 



DOMESTICUS. Chem. Conch. Cab., t. xi, p. 261, pi. 207, figs. 20302036, 1783. 

 OSTREA OBSOLETA. Turt. edit. Linn., vol. iv, p. 266, 1806. 



W. Wood. Ind. Test., p. 50, pi. 10, fig. 37. 

 Mawe. Linn. Conch., pi. 14, fig. 6. 

 TIGERINA. Turt. edit. Linn., vol. iv, p. 268, 1806. 



L^EVIS. Mat. and Back. Linn. Trans., vol. viii, p. 100, pi. 3, fig. 5, 1807. 

 W. Wood. Ind. Test., pi. 10, fig. 38. 



Spec. Char. Testa tequivalvi, aqnilaterali, suborbiculari ; radiatd, radiis variis, 

 inter dum obsoletis, striis subtilissimis arcuatim divergentibw ornatd; auriculis valde 

 inaqualibus. 



Shell equivalve, equilateral, suborbicular ; costated costee variable, sometimes 

 obsolete, or small and numerous, sometimes arranged in fives ; ornamented with fine 

 curved and diverging striae, ears very unequal. 



Diameter, 1 inch. 



Locality. Cor. Crag, Sutton, Ramsholt, Gedgrave, Sudbourn. 

 Red Crag, Sutton, Bawdsey, and Walton Naze. 



Recent, Britain and North Seas. 



This is a very abundant species in the Coralline Crag, with as great a range in 



