nSIDIUM SUPINUM. 45 



Dimensions. — L. 2 mm. B. 2 mm. 



Distribution. — Recent : irregularly distributed over the British Isles and the 

 Continent of Europe; Siberia; Algiers (Lallement). 



Fossil : Icenian Crag : Bramerton. Freshwater bed : West 

 Runton (C. Reid). Common in all the British Holocene and Pleistocene deposits ; 

 it occurs also in post-Tertiary beds on the Continent. 



Bemarhs. — The shell here figured was found by Mr. Jas. Reeve some years ago 

 in the Norwich Crag at Bramerton, from which place there are many specimens 

 in the Norwich Castle Museum. Both this and the following have been identified 

 by Messrs. Kennard and B. B. Woodward, who have also recently reported this 

 species from some beds of late Pleistocene age in the Lea Valley at Ponders End, 

 and at Edmonton near the Angel Road Station, where it was discovered by Mr. 

 S. Hazzledine Warren together with remains of the reindeer, a species of lemming, 

 and the northern willow, Salix herbacea. 



Pisidium supinum, A. Schmidt. Plate I, fig. 20. 



1850. Pisidium su/pinum, A. Schmidt, Zeitsclir. f. Malak., vol. vii, p. 119. 



1864. Pisidium Henslowianum, var. supinum, Morch, Syn. Moll. Daniae, p. 72. 



1871-2. Pisidium supiinim, Clessiu, Mai. Blatt., vol. xviii, p. 197, 1871 ; vol. xix, pi. i, fig. 3, 1872. 



1873. Pisidium supinu7n, Westerluud, Fauu. Moll. Suec, p. 533. 



1875. Pisidium (Bivtilina) siopimmi, Saudberger, Laud Sussw Couch. Vorw., p. 765. 



1879. PisidmHi, sttpmwTO, Clessin, Martiui aud Chemuitz, Couch. Cab. (Cycladiae), p. 11, pi. i, figs. 



5—7. 

 1899. Pisidium fontinale, Keuuard aud B. B. Woodward, Pi'oc. Malac. Soc, vol. iii, p. 202. 



1912. Pisidium supinum, Keuuard aud B. B. Woodward, Quart. Jouru. Geol. Soc, vol. Ixviii, p. 240, 

 pi. xvii, fig. 9. 



1913. Pisidium supinum, B. B. Woodward, Cat. Brit. Sp. Pisidium, p. 100, pi. ii, fig. 5 ; pi. iv, fig. 7 ; 

 pis. XXV, xxvi ; pi. xvii, figs. 1, 2. 



Specific Characters. — Shell small, comparatively thick and strong, ventricose, 

 inequilateral, sub-trigonal; umbones rather sharp, sometimes surmounted by a 

 projecting plate as in P. Henslowantim; surface of valves ornamented with fine 

 regular concentric striae, very strong and massive (B. B. W.) 



Dimensions. — L. *3"2 mm. B. 3 mm. 



Distributio7t. — Recent: various parts of England from Cumberland to the 

 Thames ; abroad in France and Germany. 



Fossil : Icenian Ciag : Bramerton, Beccles. Freshwater bed : 

 West Runton. Pleistocene : Thames valley, Grays ; Lea Valley, Ponders End 

 (arctic bed), Walthamstow; Barnwell, Stutton and elsewhere. Holocene : home 

 counties from Gloucestershire to the east and south-east of England. 



Lower Pleistocene : Mosbach (Sandberger). 



Remarks. — For the discovery of this species at Bramerton, where it seems to 



