﻿BIVALVIA. 



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regarded as a variety of A. sulcata, the ridged or sulcated form being the British and 

 Arctic one, and the smooth form the Mediterranean one. It appears to me, however, 

 that where such distinct forms are characteristic of separate areas it is but a question of 

 words whether for palseontological purposes we call them species or varieties, and it is 

 significant that in the Cor. Crag, with, as I consider, a fauna having its chief affinities with 

 the Mediterranean, we get no trace of sulcata, but have incrassata in profusion. Some 

 imperfect specimens have occurred in the Middle Glacial at Hopton that seem to 

 belong to this species, but being imperfect I have assigned a Middle Glacial locality to 

 it with a note of interrogation. If, however, better specimens should confirm this, we 

 should, as the undoubted sulcata occurs at Hopton, have both the Arctic and 

 Mediterranean forms together in the Middle Glacial deposit. This is probably Tellina 

 fusca, Poli. 



Astarte sulcata, Dacosta. Crag Moll., vol. ii, p. 182, Tab. XVI, fig. 5 a, b. 



Localities. Red Crag, Sutton. Fluvio-marine Crag, Bramerton and Thorpe? 

 Chillesford bed, Aldeby. Middle Glacial, Hopton. Upper Glacial, Bridlington. Post 

 Glacial, March. 



This shell still remains in the Red Crag very rare to my researches. It is given by 

 Dr. Woodward in his Norwich Crag list as occurring both at Bramerton and Thorpe, 

 the young being more frequent, but I have not been able to confirm this through any 

 of my Norwich correspondents. It has been obtained at Aldeby by Messrs. Crowfoot and 

 Dowson. In the Middle Glacial at Hopton two or three perfect valves of young 

 specimens and one full grown have occurred. It is among the specimens in the British 

 Museum from Bridlington, and Mr. Harmer has found it at March. 



Astarte Omalii, La Jonk. Crag Moll., vol. ii, p. 180, Tab. XVII, fig. 1 a—f. 



Localities. Cor. Crag passim. Red Crag, Sutton. Fluvio-marine, Bramerton? 

 Middle Glacial, Hopton. 



The principal portion of a shell, as well as some other fragments, which have occurred 

 at Hopton, enable me to refer this species to the Middle Glacial sands without 

 much hesitation. It is given in Dr. Woodward's list as from Bramerton, but I haw 

 not been able to obtain confirmation of this, and have placed a note of interrogation to 

 that locality. 



This species is referred by Mr. Jeffreys in his list to A. undulata, Gould, but its 

 identity with that shell I fully considered more than twenty years ago, and the reasons for 

 keeping the two species distinct, given by me at p. 180, vol. ii, of 'Crag Mollusca,' 

 appear to me to be still valid. If we were to strain identities in this way a suite of 

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