255 



straight ; dorsal margin convex. Hinge consisting of strongly 

 developed, crenulated processes at the angles, separated by a 

 furrow, and with corresponding depressions and ridge or bar in 

 the opposite valve ; thus differing in the character of hingement 

 from many of the associated Cytheridean forms. 



Surface smooth and convex, but strongly impressed by broad 

 sunken areas along the ventral region, and by more irregular 

 impressions in the «lorsal region, there remaining a central, 

 rounded but broken ridge. 



One specimen ; Blue Fullers-earth Clay, Midford. 



12. CYTHERE JUGLANDICA, Joiies, var. MAJOR, nOV. 



PI. iv., figs. 2 a, b. 



This form is like C juglandica (Quart. Journ. Gtol. Soc, vol. xl,, 

 1884, p. 766, pi. xxxiv., figs. 36 and 37), from the Kichmond 

 boring, in all its essentials, but is much broader (higher). , 



One specimen from the Bradford Clay, Bradford.* 



13. CYTHERE JUGLANDICA, Jones, var. MINOR, nov. 



PI. iv., figs. 3 a, b, e. 



This also approximates in all essential features to C. juglandica 

 too nearly to allow of any specific distinction. The ventral 

 ridging is much stronger in this specimen than in either the type 

 or the var. major ; but, as this only represents the longitudinal 

 ridges of the meshes in an exaggerated form, the departure from 

 the type is but slight. 



One specimen ; Blue Fullers-earth Clay, Midford. 



14. CYTHERE AVALFORDIANA, sp. 11. 



PI. v., figs. 9 a, b, c. 

 Mr. Walford's specimens were from the Fullers-earth Oolite 

 in a cutting on the Banbury-and-Cheltenham Eailway, about 



* Geol, Mag., June, 1886, p. 273. 



