Published online by Cambridge University Press: 01 May 2009
Valves subcircular, approaching subquadrate, like some small Lamellibranchs. Umbo at the antero-dorsal corner, and at aa angle of 40° to the extreme curvature of the concentric ridgelets. Hinge-line straight, behind the umbo, about half the length of the longest diameter of the valve. The other edges rounded; the anterior nearly semicircular; the ventral obliquely curving up to meet the steeper and narrower posterior curve.
page 290 note 1 Mém. Com. Géol. (St. Petersburg), vol. vi, 1888, pp. 469 and 556 Google Scholar, pl. ii, fig. 26. See also Brit. Assoo. Report for 1889, p. 66.Google Scholar
page 291 note 1 Proc. Zool. Soc., Annulosa, , 1849, p. 89, pl. xi, fig. 5.Google Scholar
page 291 note 2 Ibid., 1849, p. 90, pl. xi, flg. 7; and 1860, p. 188.
page 291 note 3 “Monogr. Foss. Esth.,” 1862, p. 103, etc., pl. iii, figs. 18–29Google Scholar; and GEOLOGICAL MAGAZINE, 1890, p. 389, Pl. XII, Figs. 1, 2.Google Scholar
page 291 note 4 “Monogr. Foss. Esth.,” 1862, p. 189 Google Scholar, etc., pl. ii, fig. 37; and GEOLOGICAL MAGAZINE, 1890, p. 387.Google Scholar