42 PLIOCENE MOLLUSCA. 



them with those in ray own collection from Grays, and from the Fen gravels, they 

 seem closely to correspond. The Recent shell originally figured by Chemnitz 

 measured, however, 30 mm. in length ; mine from Grays are only 20 mm., while 

 those from March are seldom more than 15 mm. 



Genus SPHiERIUM, Scopoli, 1777. 



Sphserium corneum (Linne). 



1758. Tellina cornea, Linne, Syst. Nat., ed. x, p. 678, no. 57. 

 1850. Cydas cornea, S. V. Wood, Men. Crag Moll, pt. ii, p. 107, tab. xi, fig. 2. 

 1853. Cyclas cornea, Forbes and Hanley, Brit. Moll., vol. ii, p. 113, pi. xxxvii, figs. 3 — 6. 

 1862. Sphasrium corneum, Jeffreys, Brit. Conch., vol. i, p. 5, pi. i, fig. 1. 

 1890. Sphperium corneum, C. Eeid, Plioc. Dep. Brit., p. 230. 



1897-1901. Sphierium corneum, Kennard and B. B. Woodward, Essex Nat., vol. x, pp. 98 et seq., 

 1897 ; Proc. Malac. Soc, vol. iii, p. 202, 1899 ; Proc. Geol. Assoc, vol. xvii, pp. 223 et seq., 1901. 



Specific Characters. — See Mon. Crag Moll., pt. ii, p. 107. 



Dimensions. — L. 9 mm. B. 11 mm. 



Distribution. — Becent : widely diffused in Great Britain; abroad from Lapland 

 and Siberia to Sicily. 



Fossil ; Icenian Crag : Bramerton, Thorpe (Norfolk), Bulchamp, 

 Easton Bavent, Southwold. Freshwater beds : Mundesley, West Runton. Many 

 localities in the Pleistocene and Holocene beds of the British Isles. 



Pleistocene : Mosbach ; Potsdam ; Somme valley. Holocene : Sweden and 

 Norway (Nordmann). 



Remarks. — This species was known to Wood from the Icenian Crag only, being 

 comparatively rare at that horizon. It is more or less common, however, in the 

 Pleistocene and Holocene deposits of this country and abroad, and is said to be 

 specially abundant in those of the Somme basin. 



Gem(.s PISIDIUM, Pfeiffer, 1821. 

 Pisidium amnicum (Miiller). Plate I, fig. 21. 



1774. Tellina amnica, Miiller, Verru. terr. fluv. Hist., pt. ii, p. 205, no. 389. 



1850. Pisidium amnicum, S. V. Wood, Mon. Crag Moll., pt. ii, p. 109, tab. xi, fig. 1. 



1853. Pisidium amnicum, Forbes and Hanley, Brit. Moll., vol. ii, p. 133, pi. xxxvii, figs. 8, 9. 



1853. Pisidium obliquum, Harting, Verb. Couim. G-eol. Kartt. Ned., p. 117. 



1862. Pisidium amnic^im, Jeffreys, Brit. Conch., vol. i, p. 20, pi. i, fig. 5. 



1885. Pisidium amnicum, Lorie, Arch. Mus. Teyler [2], vol. ii, p. 163. 



1890. Pisidium amnicum, C. Reid, Plioc. Dep. Brit., p. 230. 



1896. Pisidium amnicum, Stefanescu, Mem. Sdc. Geol. France, vol. vi, p. 81, pi. vii, figs. 40 — 55. 



