TAB. VII. 



« X 50 



^ X 50 



c X 50 



^ X 50 



d' X 50 



e X 50 



/ X 50 



y X 50 



y^ X 50 



i X 50 



a X 



h X 



c X 



d X 



e X 



a X 



^ X 



c X 



^ X 



e X 



/ X 



9 X 



h X 



«■ X 



50 

 50 

 50 

 50 

 50 



50 

 50 

 50 

 50 

 50 

 50 

 50 

 50 

 50 



Fig. 24. Cytherella ovata. 



Adult, left valve, outside . . Chalk. 



Adult, right valve, outside . 



Adult, right valve, inside 



Adult, left valve, inside 



Adult, left valve, dorsal edge 



Adult, perfect, dorsal aspect 



Adult, perfect, anterior aspect, seen obliquely 



Adult, perfect, transverse section 



Var., right valve, outside . . . Detritus. 



Young, right valve, outside . . Chalk. 



Fig. 25. Cytherella truncata. 



Adult, perfect, dorsal aspect . 

 Adult, perfect, anterior aspect . , „ 



Adult, perfect, left valve upwards . . „ 



Adult, cast of interior of carapace . Gault. 



Young, perfect, right valve upwards . .Detritus. 



Fig. 26. Cytherella Williamsoniana. 



Adult, perfect, dorsal aspect . . Gault. 



Immature, perfect, dorsal aspect 



Adult, perfect, ventral aspect 



Adult, perfect, anterior aspect 



Immature, left valve, outside 



Adult, right valve, outside . . . Chalk. 



Adult, right valve, inside . . Gault. 



Young, right valve, outside . . . „ 



Var. granulosa, right valve, outside . Chalk. 



Charing. 



Detritus. Charing. 



Leacon Hill. 

 Charing. 



Folkstone. 



Detritus. Charing. 



Gravesend. 

 Folkstone. 



Norwich. 



