﻿BIVALVIA. 



137 



Astarte borealis, Chemtt. Crag Moll., vol. ii, p. 175, Tab. XVI, fig. 3 a, b. 



Localities. Fluvio-marine Crag, Bramerton, Thorpe, and Postwick. Chillesford 

 bed, Aldeby, Bramerton, Horstead, and Coltishall. Lower Glacial, Weybourn, Belaugh, 

 and Rackkeath. Middle Glacial, Hop ton. Upper Glacial, Bridlington. Post Glacial, 

 March. 



This is one of the very few shells of the Fluvio-marine Crag, that on the assumption 

 of their being coeval deposits, might have been expected to occur also in the Red, but 

 which have not yet been found in it. Although present in the Fluvio-marine Crag at 

 Bramerton, I am informed that it is rare, while in the Chillesford bed exposed in the 

 same deep section at Bramerton it is common. It occurs in the Chillesford bed at most 

 of the localities except at Chillesford, at which place I have not heard of its occurrence ; 

 and it has been found in the Lower Glacial Sands at Belaugh, Rackkeath, and Weybourn, 

 the base of those sands at the first of these places being literally a pavement of detached 

 valves of this shell. It is not uncommon at Hopton in a fragmentary state, but only one 

 perfect valve has occurred there. The specimens from March are somewhat peculiar, 

 having fine striations, so that it was inserted by Mr. Seeley in his list of shells in the 

 ' Quart. Journ. Geol. Soc.,' vol. 22, p. 473, as A. crebricostata. The March specimens, 

 however, have not the denticulated margin of crebricostata, and some of the specimens 

 exceed in magnitude any of crebricostata that I have seen. The form called Withami 

 (fig. 3 c — d) appears to be confined to the Bridlington locality, where it occurs in 

 association with the typical form of borealis, and, so far as shape is concerned, seems to 

 bear the same relation to it that A. elliptica bears to A. sulcata; but there is not the 

 difference of a notched margin such as obtains between elliptica and sulcata. 



Astarte Burtinii, La Jonlc. Crag Moll., vol. ii, p. 188, Tab. XVII, fig. 5 a — d. 



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

 Middle Glacial, Hopton. 



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

 Woodward in his list in ' White's Directory ' as in the Norwich Crag, on the authority of 

 a single valve said to have been found there by Mr. Wigham ; but I have not been able 

 to hear of its occurrence there from other sources, and its presence in the Fluvio-marine 

 Crag must be received with doubt. I have not met with it from the Lower Glacial 

 sand or from any of the localities of the Chillesford bed. In the Middle Glacial sands 

 of Hopton several young specimens have occured, but all, except one of them, imperfect. 

 I have not met with it from any newer Glacial or from any Post Glacial bed, nor do 

 I know it as living. 



