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SUPPLEMENT TO THE CRAG MOLLUSCA. 



This shell, though occurring in the Red Crag of Butley, and found in the Chillesford 

 bed at Chillesford with the two valves united, does not appear yet to have occurred at 

 its other localities. In the Middle Glacial sand of Hopton a fragment comprising the 

 hinge and umbonal portion of the shell, showing lines of growth, has occurred. I am not 

 aware whether it be common or not at Bridlington. The genus Panqpea is certainly 

 not appropriate for this species ; but as Saxicava, in which other authors place it, appears 

 to me equally inappropriate, I have, until a more suitable genus be erected for it, 

 retained it under the generic name in which it was first figured from the Crag. 



Panopea Fatjjasii, Menard de la Groye. Crag Moll., vol. ii, p. 283, Tab. XXVII, 



%• 1 a—f. 



Localities. As in 1 Crag Moll.' 



In the 'Catal. Syst. et descr. des foss. de Terr. Tert.,' by M. C. Mayer, 1870, three 

 species are given from the English Crag as distinct, viz. P. Menardi {P. gentilis, Sow.), 

 from the Red Crag, and P. TLhudolphii {P. Ipsviciensis, Sow.), and P. Americana, Conrad, 

 from the Cor. Crag. Having, however, seen and examined a large series of the Crag 

 species of this genus, which present great variation among themselves, I am still of 

 opinion that those shells which I have represented in ' Crag Moll.' all belong to one and 

 the same species. 



Mya arenaria, Linn. Crag Moll., vol. ii, p. 279, Tab. XXVIII, fig. 2. 



Localities. Red Crag passim, except Walton. Fluvio-marine Crag passim. Chilles- 

 ford bed passim, except Chillesford. Lower Glacial, Belaugh, Rackheath, Wroxham, 

 Spixworth, and Crostwick. Middle Glacial, Hopton, Clippesby, and Billockby. Post- 

 glacial, March, Hunstanton, and Nar Brickearth, Pentney {Rose). 



This species I have not yet seen from the Cor. Crag, nor from the oldest part of the 

 Red, viz. that of Walton Naze. I have found it plentifully in the Red Crag at Sutton, 

 where the variety lata is also met with, and I have not seen this variety from any other 

 locality. It is common in the Eluvio-marine Crag at Bramerton, Avhere distortions are not 

 uncommon ; but at Chillesford, where truncata, a less littoral shell abounded, I have not met 

 with it. In the Lower Glacial sands, where they are fossiliferous, it is common. 

 Fragments are numerous in the Middle Glacial sands of Hopton, and it has been found 

 by Mr. Rose in the Nar Brickearth. 



