Conch. [mod.L. generic name, f. as TRIGON + -IA1.] A genus of bivalve mollusks having a shell of triangular form.

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1837.  Encycl. Brit. (ed. 7), XV. 343/1. The trigonia now forms along with castalia, the small family of Trigonées.

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1851.  Woodward, Mollusca, I. 11. The cockle and trigonia have the foot bent, enabling them to make short leaps.

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1883.  Fisheries Exhib. Catal. (ed. 4), 176. Collection of Trigonias … exhibited by Dr. J. C. Cox, F.L.S. of Sydney.

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  Hence Tagoniacean, a. adj. belonging to the group Trigoniacea of bivalve mollusks, typified by the genus Trigonia; b. sb. a mollusk of this group.

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In recent Dicts.

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