BIVALVIA. 199 



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

 Cytherea minima. Brown. Brit. Conch. lUust., pi. xix, fig. 3, 1827. 



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



— TRIANGULARIS. MacffH. MoU. Aberd., p. 268, 1843. 



— TRIGONA. Nyst. Coq. Foss. de Belg., p. 1/2, 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. 



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



— PUSILLA. Bonelli fide Sismonda. 



— LENTicuLA. S. Wood. Catalogue, 1840. 



ExoLETA ORBicuLATA? juv. Brown. Brit. Conch. lUust., pi. XX, figs. 19, 20, 1827. 

 Circe triangularis. Kiiir/. Ann. Nat. Hist., vol. xv, p. 112. 



— minima. Forb. and Hani. Hist. Brit. Moll., vol. i, p. 440, pi. xxvi, figs. 4, 5, 6, 8' 

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

 Crassina minima. Grui/. Ann. of Philos., 1825. 



Spec. Char. Testa parvd, ovato-rotundatd vel mbtrigond, subaquilaferali, compressd, 

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



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

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

 smooth. 



Diameter, -|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.) Lamarck. 

 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. KopdWtov, coral, and (payu, to eat. 



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