POETLAND EOCKS OF ENGLAND. 231 



Common in the creamy limestones at Coney Hill and Qnainton, 

 and in several other places. 



SowERBTA LONGiOE, spcc. nov. PI. IX. figs. 8, 8a. 



Length -J the breadth, beaks nearly median, valves moderately 

 inflated ; posterior angle well marked, almost produced at the pallial 

 border ; anterior side most convex towards the pallial border. 

 Muscular impression deep. This differs from ;S^. triangularis in the 

 great length of the posterior angle, the more rounded pallial border, 

 and more median beaks. 



In the rubbly limestones near Aylesbury, and in the Swindon 

 Sands. 



Mtoconcha portlandica, spec. nov. PI. IX. fig. 10. 



Only known by the cast, which cannot be referred to that of any 

 known species. Its general form is spathulate ; that is, it is thick 

 anteriorly and becomes broader and thinner posteriorly. It appears 

 to vary in shape in the different examples, possibly from the state 

 of preservation. In some it is more curved than in the figured 

 example. There are slight ridges on the cast radiating from the 

 umbo ; and the pallial line is crumpled ; the shell had strong folds of 

 growth, where preserved. The muscular impressions are well seen ; 

 the posterior one is large and remote. Length 4|^ inches. 



Abundant in the rubbly limestones at Coney Hill, and found 

 associated with M. Scemanni in the Swindon Sands. 



Ctprigaedia costifera, spec. nov. PL IX. fig. 11. 



Valves inflated ; apices recurved, nearly median ; posterior side 

 having its oblique area bounded by a raised rib, and concentrically 

 striated, as is the rest of the shell obscurely ; breadth a little less 

 than the length. This is very like an Isocardia. Its rib distin- 

 guishes it from all others. 



Moderately common in the creamy limestones of Coney Hill. 



AsTAETE EUGOSA, Sowcrby. 



I cannot find any difference between this and Astarte cuneata 

 among the numerous specimens I have seen. De Loriol afiirms that 

 its hinge is exactly like that of the Cyrenas of the Weald; but a com- 

 parison of it with the hinges of recent Cyrenas and Astartes, leaves 

 no doubt of its belonging to the latter, especially from a peculiarity 

 not perhaps noticed before, but very obvious on the casts from 

 Swindon. In these and in Astartes only, there are very narrow 

 lateral teeth and sockets, such that the posterior tooth is in the 

 right valve, and the anterior tooth is in the left valve, fitting into 

 sockets in the opposite valve, and so making a deep impression on 

 the cast. 



AsTAETE poLYMOEPHA, Contejean. PL IX. fig. 12, 12a. 



These specimens agree very well with the author's description ; 

 but being very characteristic of the Swindon Sands, and possibly 



