BIVALVIA. 199 



Cyprina triangularis. Turt. Brit. Biv., p. 136, pi. ii, figs. 19, 20, 1822. 

 Cytheeea minima. Brown. Brit. Concli. Illust., pi. xix, fig. 3, 1827. 



— MINUTA. Id. „ „ pi. xix, fig. 4, 1827. 



— TRIANGULARIS. Macgil. Moll. Aberd., p. 268, 1843. 



— TRiGONA. Nyst. Coq. Foss. de Belg., p. 172, pi. xii, fig. 4, 1844. 



— APicALis. Phil. En. Moll. Sic, vol. i, p. 40, pi. iv, fig. 5, 1836. 



— — Forbes. jEgean Invert. Rep. Brit. Assoc, p. 182, 1843. 



— CYRiLLi. Phil. En. Moll. Sic, vol. ii, p. 32, 1844. 



— PUSiLLA. Bonelli fide Sismonda. 



— LENTicuLA. S. Wood. Catalogue, 1840. 



ExoLETA ORBicDLATA? juv. Browti. Brit. Conch. lUust., pi. XX, figs. 19, 20, 1827. 

 Circe triangularis. King. Ann. Nat. Hist., vol. xv, p. 112. 



— minima. Forb. and Hani. Hist. Brit. Moll., vol. i, p. 446, pi. xxvi, figs. 4, 5, 6, 8' 

 and Animal, PL m, fig. 3, 1848. 

 Crassina minima. Gray. Ann. of Philos., 1825. 



Spec. Char. Testa parvd, ovato-rotimdatd vel suhtri(jond, subaquilaterali, compressd, 

 transversim striatd, striis lavibus, convexis ; lunuld distinctd ; margine integerrimo. 



Shell small, roundedly ovate, or of a subtrigonal form, nearly equilateral, com- 

 pressed, transversely striated, striee rounded and smooth ; lunule distinct ; margin 

 smooth. 



Diameter, f ths of an inch. 



Localities. Cor. Crag, Sutton. 

 Red Crag, Sutton. 



Recent, iEgean, Mediterranean, Britain, Zetland. 



This species, in the Coralline Crag, is very abundant ; my cabinet contains only two 

 individuals from the Red Crag. In outward form it presents considerable variation, 

 some specimens having a longitudinal diameter much greater than its height, while in 

 others the height exceeds the length ; the prominence in the umbo of some individuals 

 gives rather an angularity to the upper part of the shell, but there is no distinct 

 triangular variety. 



CoRALLioPHAGA.* De Blainv., 1824. 



CYPRICARDIA (sp.) Lamorck. 

 Venerupis (sp.) Basterot. 



Gen. Char. Shell transversely ovate or oblong, equivalved, inequilateral, closed ; 

 rugged or smooth externally ; hinge furnished with two teeth in each valve, or two 

 diverging in one valve, with one triangular and interlocking in the other. Two ovate 

 muscular impressions ; mantle mark with small indented sinus. Ligament external. 



* Etym. KopdWiov, coral, and ^uya», to eat. 



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