PLATE VI. 



Fig. 1. — Carbonicola acuta. Left valve, showing single median cardinal tooth. 

 From the Cockshead Rock, Adderley Green. My Collection. (Page 50.) 



Fig. 2. — Carbonicola acuta. Right valve, showing a slight indication of a 

 posterior lateral tooth. Same locality. My Collection. (Page 50.) 



Fig. 3 — 42. — Carbonicola acuta. A series from the same locality, exhibiting 

 several variations in detail and form of the hinge apparatus. (Page 50.) 



Fig. 43. — Carbonicola acuta. A left valve from the Collection of the Wood- 

 wardian Museum, Cambridge, from Bradford, Yorkshire, showing the absence of a 

 posterior lateral tooth. (Page 50.) 



Fig. 44. — Carbonicola subconstricta. A right valve from the same Collection 

 and locality, showing a posteriorly diverging cardinal tooth with a corresponding 

 pit posterior to it to receive the cardinal tooth of the opposite valve, and the absence 

 of a lateral tooth. (Page 59.) 



