110 CRETACEOUS LAMELLIBRANCHIA. 
Types.—I have not seen the types; they were obtained from the Hythe Beds, 
near Hythe. The type of M. spathulatus, Seeley, from the Barnwell Gravel 
(derived from the Chalk), is in the Woodwardian Museum, Cambridge. 
Distribution.—Hythe Beds of Hythe and Lympne. Lower Greensand of 
Faringdon and Seend. Upper Greensand of Chilfrome (Dorset), and near 
Weymouth. Greensand of Haldon. Chloritie Marl of Maiden Bradley. Ceno- 
manian (Me¥er’s Bed 12) of Dunscombe and Kempstone Rocks (Sidmouth). Chalk 
Marl of Chardstock. Basement Bed of Chalk Marl of Cerne Abbas. Cenomanian 
Sands of Wilmington. Lower Chalk of Burwell and Stoke Ferry. Chalk Rock of 
Winchester, Cuckhamsley, Luton cutting, and Underwood Hall (Dullingham). 
Upper Chalk of Northfleet. Flint gravel (derived from Upper Chalk) near 
Ventnor. Zone of Bel. quadrata of Winchester and Salisbury. Zone of Bel. 
mucronata of Salisbury and Norwich. 
fenus—DREISsENsIA, P. van Beneden, 1835. 
(Ann. Sci. Nat.,’ ser. 2, vol. iii, p. 198, pl. viii. Emend. P. Fischer, ‘Man. de Conch.,’ 1886, p. 972.) 
DREISSENSIA LANCEOLATA (Sowerby), 1823. Plate XVIII, figs. 13—15; Plate XIX, 
figs. 1—11. 
1823. Myrinus mpentunus, J. de CO. Sowerby. Min. Conch., vol. v, p. 55, pl. 
cecexxxix, fig. 1. 
1828. — LANCEOLATUS, Sowerby. Ibid., fig. 2. 
1836. — TRIDENS, J. de C. Sowerby. Trans. Geol. Soc., ser. 2, vol. iv, 
p. 342, pl. xvii, fig. 14. 
1836. — PRHELONGUS, Sowerby. Tbid., p. 342, pl. xvii, fig. 15. 
1844. — LANcEoLatus, A. d’Orbigny. Pal. Franc. Terr. Crét., vol. iu, 
p. 270, pl. ecexxxviii, figs. 5, 6. 
1844. — raucatus, d’Orbigny. Ibid., p. 280, pl. ecexli, figs. 11—13. 
1845. — LANCEOLATUS, var. EDENTULUS, E. Forbes. Quart. Journ. Geol. 
Soc., vol. i, p. 248. 
? 1846. — = A. E. Reuss. Die Verstein. der bohm. Kreide- 
format., pt. 2, p. 15, pl. xxxvii, fig. 5. 
1848. — — H. G. Bronn. Tndex Palaeont., vol. i, p. 773. 
1850. Muirytus asruptus, A. d’Orbigny. Prodr. de Pal., vol. ii, p. 107. 
1850. — suBFALCATUS, d’Orbigny. ITbid., p. 166. 
1850. — LANCEOLATUS, @’Orbigny. Ibid., p. 166. 
1854. Myriivus epentuuus, J. Morris. Cat. Brit. Foss., ed. 2, p. 215. 
1854. — LANcEOLATUS, Morris. Ibid., p. 215. 
1854, — prmHLonevs, Morris, Ibid., p. 215, 
