Tellina praetenuis, Leathes.
- balthica, Linn.
- crassa, Gmelin.
Donax vittatus, Dacosta
Scrobicularia plana, Dacosta.
Mactra ovalis, Sow.
- subtruncata, Dacosta.
- solida, Linn.
Thracia papyracea, Poli.
Mya truncata, Linn.
- arenaria, Linn.
Panopaea norvegica, Spengl.
Saxicava rugosa, Linn.
- arctica, Linn.
Pholas crispata, Linn.
Corbula striata, Walk. & B.
Profuse in Red and Fluvio-marine crag and Chillesford beds. Rare in Lower Glacial.
Profuse in Lower and Middle Glacial, and in all Glacial and Postglacial beds.
Common in crag, and fragments. Common in Middle Glacial.
S. piperata, Gmel. Hinge-fragments common in Middle Glacial.
M. elliptica of British authors.
- Bradwell.
Doubtful fragments only, in Middle Glacial.
One perfect specimen from Lower Glacial.
The gigantic form of Uddevalla and the Clyde beds.
C. gibba, Oliv. Profuse in Coralline and Fluvio-marine Crags, Chillesford bed and Lower Glacial. Common in Middle Glacial. Rare in Red Crag.
Note.-O, P signifies that the form is extinct unless represented by a Pacific shell; O, not known living; N. A, occurs no nearer than North-east America; A, only within the Arctic Circle; S, only to the south of the British Seas; B, A, S, in British Arctic, and coast being included under this letter. The shells marked * Bradwell are inserted in the Middle-Glacial column on the authority of a list of identifications made by Mr. Gwyn Jeffreys of some shells and fragments obtained by Mr. G. B. Rose from the Middle-Glacial cutting of Bradwell (by Breydon), supplied by Mr. Rose.
N. B. In the foregoing list the Crag column embraces all the divisions of that formation from the Coralline Crag up to, and inclusive of, the Chillesford beds.
Summary.
Lower-Glacial Shells.
Middle ditto.
Upper ditto (Bridlington).
N. B. In the case of the Middle-Glacial shells, the number in column O is swelled by the two new shells and by two marked with ? being included in it.
