PLATE VI. 



FIGS. PAGE 



1-3. Trigonia vau Sharpe... ... ... ... ... ... ... 110 



1. Left valve, dorsal aspect ; la, umbonal region of the same 

 valve, x 2. Three hundred yards below Addo Drift (Tunbridge's), 

 left bank of Sunday's Eiver (41h). 



2. Eight valve ; 2a, dorsal aspect ; 2b, frontal aspect. Same 

 locality (40h). 



3. Interior of a right valve. Same locality (42h). 



4,5. Trigonia stowi sp. nov 115 



4. Eight valve ; 4a, frontal view ; 4&, dorsal aspect of the umbonal 

 region of right valve and fragment of left valve, showing details 

 of sculpture. Above Modder Drift, Sunday's Eiver. In the col- 

 lection of the Geological Society of London (No. 12006). 



5. Left valve. From the South African Museum collection ; 

 probably Sunday's Eiver. 



