TAB. II. 



a 



X 



50 



h 



X 



50 



c 



X 



50 



d 



X 



50 



e 



X 



50 



e 



xioo 



f X 



50 



// 



X 



50 



a 



X 



50 



h 



X 



50 



(- 



X 



50 



a 



X 



50 



h 



X 



50 



<: 



X 



50 



a 



X 



50 



e 



X 



50 



h 



xioo 



h 



X 



50 



f 



X 



50 



<:. 



X 



50 



d 



X 



50 



() X 50 



a X 50 

 ^ X 50 

 c. X 50 



tt X 50 

 a X 50 



«"X 



50 



h X 



50 



5'X 



50 



^X 



50 



Fig. 3. Cythere timhonata. 



Perfect, dorsal aspect . . . Detritus. Charing. 



Perfect, ventral aspect . . . ,, 



Young, perfect, ventral aspect . . „ 



Perfect, posterior aspect . . . ,, 



Perfect, placed obliquely, left valve upwards ,, 



Punctations (of fig. 2>c) . . ,, 



Right valve, outside . . . „ 



Left valve, inside . . • „ 



Fig. 4. Cythere Faba. 



Perfect, right valve upwards . . Detritus. Charing. 



Perfect, dorsal aspect . . . „ ,, 



Perfect, anterior aspect . . „ „ 



Fig. 5. Cythere Bairdiana. 



Right valve, inside . . . Greensand. Farringdon. 



Right valve, dorsal edge . . . ,, ,, 



Right valve, anterior aspect . . ,, 



b"'x 50 



Fig. 6. Cythereis intermpta. 



Left valve, outside 

 Perfect, dorsal aspect . 

 Punctations 



Var. a, left valve, outside 

 Var. o, perfect, ventral aspect 

 Var. |3, left valve, outside 

 Var. )3, right valve, inside 

 Var. |3, perfect, anterior aspect 



Fig. 7. Cythereis Galtina. 



Right valve, outside 

 Left valve, inside 

 Left valve, dorsal edge 



Fig. 8. Cythereis macrophthahna 



Left valve, outside 

 Left valve, inside 

 Left valve, dorsal edge 

 Right valve, outside 

 Right valve, inside 

 Right valve, dorsal edge 

 Right valve, anterior edge 



Detritus. Charing. 



Gault. Leacon Hill. 

 ,, Folkstone. 



Gault. Folkstone. 



Chalk. 



Norwich. 



