BIVALVIA. IN) 
Anoponta cyanea, Linn. Crag Moll., vol. ui, p. 102, Tab. II, fig. 10. 
This is also an abundant shell at Grays, and by no means scarce at Clacton, but 
from extreme fragility specimens are difficult to obtain. I have also found in the bed at 
Runton (C of Sect. III of the map sheet) the variety anatina or paludosa, ‘Turt. Brit. 
Biv.,’ p. 240, Tab. 15, fig. 6, in which the dorsal and ventral margins are nearly parallel. 
My specimen from Runton measures nearly five inches in length. 
Unio margaritifer is given by Mr. Prestwich in the ‘Quart Journ. Geol. Soc.,’ vol. 
Xxvil, p. 467, as a species from near Runton Gap on the Norfolk Coast, but this appears 
to be an error, as pointed out by Mr. A. Bell in ‘ Geol. Mag.,’ vol. ix, p. 214. I do not 
know this shell as a British fossil. 
‘CorBICULA FLUMINALIS, A/iiller. Crag. Moll., vol. u, p. 104, Tab. XI, fig. 15, as Cyrena 
consobrina. 
Localities. Red Crag, Waldringfield (4. Bell). Fluvio-marine Crag. Thorpe, near 
Aldbro (8. Wood). Dunwich (Crowfoot). Bramerton and Postwick (Woodward). 
Bulchamp (Dowson). Lower Glacial, Belaugh (armer). Post Glacial, Bramwell near 
Cambridge (Bell). Kelsea Hill, Gedgrave near Orford, Stutton-on-Stour, Grays, and 
Clacton (fisher). 
This shell (like several European freshwater bivalves) has a great number of 
‘synonyms,' and it is an important species as concerns the post glacial sequence of deposits. 
It is somewhat variable, but not more so than other of our freshwater inhabitants. It 
has been said that freshwater shells vary more than marine, but I have never seen 
greater variation among them than is exhibited by the varieties and distortions shown by 
fossil specimens of Zrophon antiquus and Littorina littorea. 
The Red Crag appears to be the oldest deposit in which Corbicula fluminalis has been 
met with in this country. ‘The specimens of this species mentioned by me as having 
been found on the top of the Cor. Crag at Gedgrave (‘ Crag Moll.,’ vol. 1, p. 105) belong 
to what is probably one of the older Post Glacial deposits, into which some of the Cor. 
Crag fossils have been washed. It appears to have lived in Britain before the very severe 
conditions of the Glacial Period had set in, and we find it again an inhabitant of our 
waters in deposits more recent than those of that epoch, but all the specimens that I have 
seen from the beds of Crag age, as well as the solitary specimen I have seen from the 
Lower Glacial sands at Belaugh, are small; the largest of them scarcely more than half 
1 This species, including the fossil in Europe and the recent shell from the Nile and China, has had 
given to it five generic and sixteen specific names. Mr. Gregory (‘ Geol. Mag.,’ vol. vi, p. 81) gives this as 
living in the Vaal River, South Africa. 
