172 SUPPLEMENT TO THE BRITISH 



to the localities already recorded, Mr. J. Parker found many fine example of this species 

 in the Cornbrash of Kidlington Pit, east of the railway beyond Woodstock Road 

 Station ; also at Bicester, and at the Langford Lane Pit and Combe Pit, about two miles 

 west of Hanborough Station, near Oxford. Prof. Prestwich furnished me with many fine 

 examples from the same localities from the Oxford Museum. Mr. James Parker states 

 that he has found W. obovata in the Oxford Clay of St. Clements, Oxford. I have seen 

 the specimens, which certainly belong to the species, but I feel surprised at their geolo- 

 gical position. 



151. Var. Siddingtonensis, Walker MS. Sup., PI. XXII, figs. 12, 13, 14. 



This variety is much more elongated, and has been sometimes mistaken for W. digona 

 Specimens of a yellow colour from the Cornbrash of Siddington, near Cirencester, 

 simulate that species. It occurs likewise at Yaxley, near Peterbro', and at Stanton, in 

 Wiltshire. It has been found in the Cornbrash near Scarborough, and by Mr. Bell in 

 the same formation at Burton Hill, near Malmsbury. 



152. Var. sub-obovata, Walker MS. Sup., PI. XXII, figs. 15, 16. 



This shell is, to all appearances, consistent in shape in both large and small 

 specimens, and consequently, perhaps, deserving of a distinctive designation. It is 

 wedge-shaped and broadly rounded laterally, as well as in front ; almost as broad as long ; 

 with valves about equally deep, moderately convex and flatter ; the edges of the valves 

 are sharper than in the typical form ; the beak is very slightly convex ; foramen small, 

 and separated from the hinge-line by a deltidium in two pieces. It occurs abundantly 

 associated with T. intermedia in the Cornbrash of Yaxley, near Peterborough, and at 

 Kidlington, near Banbury, in Oxfordshire. 



153. Var. Stiltonensis, Walker MS. Sup., PI. XXII, figs. 17, 18, 19, 20. 



This variety is very much pinched in laterally near the front, and closely resembles 

 W. bucculenta. It is longer than wide, and often very much thickened at the margin. 

 It occurs in the Cornbrash at Stilton. The late Mr. Leckenby found it in the Cornbrash 

 near Scarborough. 



This variety of W. obovata has often been called W. ornithocephala, var. in lists of 

 Cornbrash fossils. Mr. E. Deslongchamps states, in his description of W. obovata, that 

 it approaches by its general shape W. digona, but that it can be distinguished by its 

 much more convex valves, that its beak is more carinated laterally, and that it is the 

 passage-form between W. digona and W. ornithocephala. 



