Candona praevara Zhang & Zhang 1982

Candona praevara Zhang & Zhang, 1982 Figs. 2, 4I–R, 5A–B. 1982 Candona praevara —Zhang & Zhang: p. 365–366, pl. 2, figs. 4–5. Material. More than one hundred carapaces. Dimensions. L: 0.62–0.68 mm, H: 0.34–0.43 mm, W: 0.24–0.31 mm. Description. Medium sized, elongated oval in lateral view. Maximum length at 2/3 of height, maximum height at 3/4 of length, and maximum width slightly behind mid-length. LV larger than RV; LV overlapping RV along all margins, including hinge margin. Anterior margin narrow and slightly supracurvate; anterior cardinal angle rounded. Posterior margin broader than anterior one, strongly infracurvate; posterior cardinal angle more rounded than anterior one. Dorsal margin arched, hinge margin long and gently slopes towards anterior margin but slopes more steeply towards posterior margin. Ventral margin nearly straight in LV, but somewhat concave in mid-length of RV. Surface smooth. Remarks. The general morphology of specimens in this study is well matched with Candona praevara with an elongated oval carapace shape, maximum height at 3/4 of length in lateral view, LV overlapping RV along all margins, and a strongly infracurvate posterior margin. Distribution. Xiaonangou Formation, upper part of the Fuxin Formation in western Liaoning (Zhang 1985) and Quantou Formation of the Songliao Basin (Zhang 1987).