﻿BIVALVIA. 



113 



It was a small flat specimen, with neither the angularity of outline nor the elevated 

 umbo of the recent Pacific shells. 



Nucula laevigata, <7". Soto. Crag Moll., vol. ii, p. 81, Tab. X, fig. 8, and var. calva. 



Supplement, Tab. VIII, fig. 5 a, b. 



Localities. Red Crag passim. 



Var. calva. Cor. Crag, Sutton and Orford. 



The Coralline Crag variety differs from the typical form found in the Red Crag of 

 Walton Naze in being smaller and more decidedly truncated, without the projecting part 

 of the margin at the shorter or siphonal side of the valve. I propose to distinguish it as 

 a well-marked variety under the above name, calva. 



This variety much resembles an Oligocene shell represented by Dr. Speyer (' Die 

 Ober Oligocanen Tertiar gebilde,' p. 42, Tab. V, figs. 3 — 5), called N. peregrina, Desh., 

 which, judging from the figure, seems to be of a form somewhat intermediate between the 

 Red and Cor. Crag shells, but I have not been able to procure a specimen of the German 

 fossil for comparison. 



Nucula proxima, Say. Crag Moll, vol. ii, p. 87, Tab. X, fig. 7 (as N. trigonula). 

 Nucula proxima, Say. Journ. Acad. Nat. Sc., 2, p. 270, 1822. 

 Localities. Cor. Crag, Sutton and near Orford. 



At the above reference I observed that N. proxima of the American authors was 

 probably the same as the Crag shell trigonula, and as I have seen no reason to alter that 

 opinion it is only right, as the name proxima has priority to mine, that the shell should 

 be here placed under that designation. 



Nucula nitida, G. Soiv. Supplement, Tab. X, fig. 12. 



Nucula nitida, G. Soiv. Conch. Illustr., Nucula, No. 29, fig. 20. 

 — — Hanley. Thesaurus, p. 46, pi. 229, fig. 120. 



Localities. Cor. Crag, Sutton and near Orford. 



As the British conchologists seem to consider this shell to be a distinct species I 

 have here followed their example, although at page 87 of vol. ii of the ' Crag Mollusca ' I 

 considered it to be only a variety of trigonula, and as my specimens correspond with the 

 recent form I have had one figured. It is less tumid than trigonula and has a smooth 



