Plate XXXIV. 



FIGS. PAGE 



1,2. Tr igonoarca cajiensis (Griesh.) ... ... ... ... ... 288 



1«, right valve ; Ih, hinge of same. 



'2a, left valve ; 2h, dorsal view ; '2(\ hinge. 



3-7. Nemodon natalensis (Ba.[\y) 289 



3a, left valve ; 'db, part near the middle of the valve x 3. 



4. Left valve of a variety with smaller ribs. Griesbach Collection. 



5«, right valve ; 5/>, dorsal view. 



6. Interior of left valve. 



7. Ribs near the anterior third of right valve x 4. Griesbach 

 Collection. 



8-12. Pectunculus africa7ius (Griesb.) 291 



8. Left valve. 



9«, the type, right valve ; 9h, posterior part x 6 ; 9(', anterior 

 part X 6. Griesbach Collection. 



10. Interior of right valve. 



11. Right valve. 



12. Griesbach Collection. Left valve. 



