162 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 Panopea is certainly 
not appropriate for this species; but as Saxicava, in which other authors place it, appears 
to me equally inappropriate, | 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 Fausasu, Menard de la Groye. Crag Moll., vol. ii, p. 288, Tab. XXVII, 
fig. la—/. 
Localities. As in ‘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. Rhudolphii (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. ui, 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 (ose). 
This species | 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 data is also met with, and I have not seen this variety from any other 
locality. It iscommon in the Fluvio-marine Crag at Bramerton, where distortions are not 
uncommon ; but at Chillesford, where ¢rwncata, 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. 
