BIVALVIA. 107 
1. Cyctas rivicota, Leach. MSS. 
TELLINA coRNEA. Linn. Syst. Nat., ed. 12, No. 72, p. 1120 (part), 1767. 
— — Var. B. Mat. and Rack. Linn. Trans., vol. viii, p. 59. 
Carpium corneum. Mont. Test. Brit., p. 86, 1803, Var. 
— nux. Da Costa. Brit. Conch., p. 189. 
Cyctas cornea. Drap. Moll. Terr. et Fluy. Fr., p. 128, t. 10, igs. 1—3. 
— — Brard. Coq. Ter. et Fluy. des Eny. de Par., p. 219, t. 8, figs. 2, 3. 
— rivicota. “ Leach’ in Lam. Hist. des An. s. Vert., t. v, p. 558, 1815. 
= — Turt. Brit. Biv., p. 248, pl. 11, fig. 13, 1822. 
— Pfeiff. Land und Sussw. Moll., p. 121, pl. 5, figs. 3—5, 1821. 
— — Sowerby. Genera of Shells, No. 38, Cycuas. 
— — G. Sow., Jr. Conch. Man., fig. 111, 1842. 
_ — Forb. and Hanl. Hist. Brit. Moll., vol. ii, p. 111, pl. 37, figs. 1, 2. 
Ency. Meth., pl. 302, fig. 5. 
Spec. Char. Testé transversd, ovati, tumiduld, crassiusculd, subequilaterd, antice et 
postice convexd ; concentricé striata ; ligamento cardinali conspicuo. 
Shell transversely ovate, somewhat tumid and strong, slightly imequilateral, 
anterior and posterior sides rounded: finely striated concentrically; cardinal area 
conspicuous. 
Length, \ inch. Height, 3ths. 
Locality. Southend (Warburton), Faversham (Zrimmer). 
I have not myself met with this species as a fossil, but specimens in that state 
have been obtained by Messrs. Warburton and Trimmer, from Faversham and 
Southend. The specimens referred to are in the Museum of the Geological Society. 
2. CycLas corNEA, Linnaeus. Tab. XI, fig. 2, a—dé. 
TELLINA corNEA. Linn. Syst. Nat., ed. 12, No. 72, p. 1120, 1767. 
— — Chem. Conch. Cab., t. vi, p. 136, t. 13, fig. 133, bad. 
— = Penn. Brit. Zool., ed. 4, p. 89, pl. 49, fig. 36. 
— — Donov. Brit. Shells, vol. iii, t. 96, 1802. 
— rivauis. Mill. Verm. Hist., t. u, p. 202. 
— STAGNICOLA. Sheppard, Linn. Trans., vol. xiv, p. 150, 1825. 
Carpium corneum. Mont. Test. Brit., p. 86, 1803. 
Cyctas cornna. Pfeiff. Deutsch. Land und Sussw. Moll., p. 120, t. v, figs. 1, 2, 1821. 
—_— — Turt. Brit. Biv., p. 248, pl. 11, fig. 14, 1822. 
— — Gray. Man. Land and F.-W. Shells, p. 280, pl. 1, fig. 2, 1840. 
_— — Jenyns. Trans: Camb. Philos. Soc., p. 295, 1831. 
— — Phil. En. Moll. Sic., vol. ii, p. 30, 1844. 
—_ — Forb. and Hanl. Hist. Brit. Moll., vol. ii, p. 113, pl. 37, figs. 3—6, 1849. 
— rivauis. Drap. Moll. Terr. et Fluv., p. 129, pl. 10, figs. 4, 5, 1805. 
= — Brard. Coq. Terr. et Fluy. Eny. de Paris, p. 222, pl. 8, figs. 4, 5, 1815. 
— FLAVESCENS. Mae Gilliv. Moll. Aberd., p. 246, 1843, fide Ford. and Hanl. 
Spec. Char. Testa transversd, ovatd, inflata, tenui, et fragili, subinequilaterd ; posticé 
majiore, subquadratd, antice rotundatd, concentricé striatd, margine ventrali leviter arcuatd, 
apicibus obtusis. 
