265 



The small notches seen at the anterior hinge are probably due 

 to fracture. Ornament consisting of delicate longitudinal ridges, 

 bearing short, sharp spines. Hingement, as in pi. i., fig. 2. 

 One specimen ; Blue Fullers-earth Clay, Midford, 



37. CYTHERIDEA SUBTRIGONA, Sjp. n. 



PI. ii,, figs. 9 a, h, c. 



This form differs from Cijtheridea obovaia, pi. ii., fig. 6, in 

 having a narrower anterior, and a broader posterior margin ; and 

 in being somewhat angular at the shoulder or front end of the 

 hinge-line. The edge and end views are less convex than those 

 of C. obovo.ta. Hingement, the same as pi. i., fig. 2, 



Terquem's Cytheridea fahacea (op. cit. p. 27, pi. iv., fig. 4) is 

 allied to the form here figured and described. 



Three or four examples ; Blue Fullers-earth Clay, Midford. 



38. CYTHERIDEA POLITULA, sp. n. 



PI. v., figs. 7 a, b, c. 



Small, sub-triangular, smooth, and sparsely pitted. Cytheridea 

 perforata of the Tertiary and Cretaceous formations is allied to 

 this form. The tubules at the base of the pits appear falsely as 

 spinules, in some lights, under the microscope. 



One specimen from the base of the Fullers-earth Oolite 

 between Notgrove and Bourton. In Mr. Walford's collection. 



39. CYTHERIDEA BLAKE AN A, Jones. 

 PI. ii., figs. \\ a,b, c. 



Cythere Blakeana, Jones, Quart. Journ. Geol. Soc, vol. xl., 1884, 

 p. 772, pi. xxxiv., figs. 34, 35. 



This appears to be the same as Cythere Blakeana from the 

 Eichmond boring. Although slightly narrower posteriorly, it 

 agrees in the hingement (as in pi. i., fig. 2) and other important 

 U 



